Version October 2024
Ensure that patients treated with aminoglycosides are under close clinical observation because of the potential toxicity associated with their use.
As with other aminoglycosides, gentamicin is potentially nephrotoxic. The risk of nephrotoxicity is greater in patients with impaired renal function and in those who receive high dosages or prolonged therapy.
Neurotoxicity, manifested by ototoxicity, both vestibular and auditory, can occur in patients treated with gentamicin, primarily in those with preexisting renal damage and in patients with healthy renal function treated with higher doses and/or for longer periods than recommended. Aminoglycoside-induced ototoxicity is usually irreversible. Other manifestations of neurotoxicity may include numbness, skin tingling, muscle twitching, and convulsions.
Closely monitor renal and eighth cranial nerve functions, especially in patients with known or suspected reduced renal function at onset of therapy, and also in those whose renal function is initially normal but who develop signs of renal dysfunction during therapy. Examine urine for decreased specific gravity, increased excretion of protein, and the presence of cells or casts. Periodically determine serum urea nitrogen (BUN), serum creatinine, or creatinine clearance (CrCl). When feasible, it is recommended that serial audiograms be obtained in patients old enough to be tested, particularly high-risk patients. Evidence of ototoxicity (dizziness, vertigo, tinnitus, roaring in the ears, or hearing loss) or nephrotoxicity requires dosage adjustment or discontinuance of the drug. As with the other aminoglycosides, on rare occasions, changes in renal and eighth cranial nerve function may not manifest until soon after completion of therapy.
Monitor serum concentrations of aminoglycosides when feasible to ensure adequate levels and to avoid potentially toxic levels. When monitoring gentamicin peak concentrations, adjust dosage so that prolonged levels above 12 mcg/mL are avoided. When monitoring gentamicin trough concentrations, adjust dosage so that levels above 2 mcg/mL are avoided. Excessive peak or trough serum concentrations of aminoglycosides may increase the risk of renal and eighth cranial nerve toxicity. In the event of overdose or toxic reactions, hemodialysis may aid in the removal of gentamicin from the blood, especially if renal function is, or becomes, compromised. The rate of removal of gentamicin is considerably less by peritoneal dialysis than by hemodialysis.
Avoid concurrent and/or sequential systemic or topical use of other potentially neurotoxic and/or nephrotoxic drugs, such as cisplatin, cephaloridine, kanamycin, amikacin, neomycin, polymyxin B, colistin, paromomycin, streptomycin, tobramycin, vancomycin, and viomycin. Other factors that may increase patient risk of toxicity are advanced age and dehydration.
Avoid the concurrent use of gentamicin with potent diuretics, such as ethacrynic acid or furosemide, since certain diuretics by themselves may cause ototoxicity. In addition, when administered intravenously (IV), diuretics may enhance aminoglycoside toxicity by altering the antibiotic concentration in serum and tissue.
Aminoglycosides can cause fetal harm when administered to a pregnant woman.
Dosage guidance:
Dosing: Determination of dosing interval requires consideration of multiple factors including concomitant medications (eg, ibuprofen, indomethacin), history of birth depression, birth hypoxia/asphyxia, and presence of cyanotic congenital heart disease. Dosage should be individualized based upon serum concentration monitoring. Impact of extracorporeal membrane oxygenation (ECMO) on neonatal pharmacokinetic parameters is not fully elucidated; optimal dose and frequency not established in ECMO patients; available data are very limited (Ref). Patient-specific considerations (eg, reason for ECMO) and variability with ECMO procedure itself make extrapolation of pharmacokinetic data and dosing to all patients receiving ECMO difficult; closely monitor serum concentrations and determine individual dosing needs in these patients.
General dosing; susceptible infection: Limited data available: Dosing strategies may vary by institution as a wide variety of extended-interval dosing regimens have been studied (Ref). Due to maturational processes and developing pharmacokinetics, regimens referred to as "extended-interval" in neonates do not typically achieve concentrations that would be expected with extended-interval dosing in children and adults (Ref). Some dosing is based on tobramycin studies.
Age-directed dosing (Ref): IM, IV: Note: Higher doses and different dosing intervals may be required to achieve target concentrations if MIC ≥1 mg/L (Ref).
|
Gestational Age |
Postnatal Age |
Dose |
|---|---|---|
|
<30 weeks |
≤14 days |
5 mg/kg/dose every 48 hours |
|
≥15 days |
5 mg/kg/dose every 36 hours | |
|
30 to 34 weeks |
≤10 days |
5 mg/kg/dose every 36 hours |
|
11 to 60 days |
5 mg/kg/dose every 24 hours | |
|
≥35 weeks |
≤7 days |
4 mg/kg/dose every 24 hours |
|
8 to 60 days |
5 mg/kg/dose every 24 hours |
CNS infection (VP-shunt infection, ventriculitis): Limited data available: Intraventricular/intrathecal (use a preservative-free preparation): 1 mg/day (Ref). Note: A trial evaluating routine use of a higher dose (2.5 mg/day) reported a higher mortality rate in the intraventricular treatment group (Ref).
Dosing adjustment in renal impairment: Consider single-dose administration with serum concentration monitoring rather than scheduled dosing in patients with urine output <1 mL/kg/hour or if serum creatinine significantly increases from baseline.
Dosage guidance:
Dosing: Initial dosing recommendations presented. Monitoring of serum concentrations is recommended to ensure efficacy and avoid toxicity, particularly in critically ill patients with serious infection or in disease states known to significantly alter aminoglycoside pharmacokinetics (eg, cystic fibrosis, burns, major surgery). Timing and frequency of concentration monitoring is individualized based on dosing and monitoring strategy (Ref). Routes of administration may vary (including IM, IV, intraperitoneal, intrathecal, and intraventricular); use caution. Some dosing is based on tobramycin studies.
Dosing consideration for obesity: In obese pediatric patients, use adjusted body weight (IBW + 0.4 [TBW – IBW]) to calculate initial dosage (Ref). Alternatively, adjusted body weight for obese pediatric patients may be calculated using the equation 0.7 x TBW (Ref), or fat-free mass can be used to calculate the initial dose in pediatric patients ≥2 years regardless of body habitus (Ref). Dosage should then be individualized based upon serum concentration monitoring.
General dosing, susceptible infection: Note: Optimal dose and frequency not established in patients receiving extracorporeal membrane oxygenation (ECMO); patient-specific considerations (eg, reason for ECMO) and variability with ECMO procedure itself make extrapolation of pharmacokinetic data and dosing to all patients receiving ECMO difficult; closely monitor serum concentrations and determine individual dosing needs in these patients.
Conventional dosing: Infants, Children, and Adolescents: IM, IV: 2 to 2.5 mg/kg/dose every 8 hours (Ref).
Extended-interval dosing: Limited data available:
Weight-directed: Infants, Children, and Adolescents: IV: 5 to 7.5 mg/kg/dose every 24 hours in patients with normal renal function (Ref).
Age-directed: Based on data from 114 patients, the following has been suggested (Ref):
Infants and Children ≥3 months to <2 years: IV: 9.5 mg/kg/dose every 24 hours.
Children 2 to <8 years: IV: 8.5 mg/kg/dose every 24 hours.
Children ≥8 years and Adolescents: IV: 7 mg/kg/dose every 24 hours.
CNS infection:
Meningitis, including health care-associated meningitis: Infants, Children, and Adolescents: IV: 7.5 mg/kg/day divided every 8 hours in combination with other antibiotics; duration should be individualized based on patient characteristics, infecting organism, and response (Ref).
Ventriculitis, including health care–associated ventriculitis and cerebrospinal fluid (CSF) shunt infections: Limited data available; optimal dose not established (Ref). Dosage and administration interval can be adjusted based on CSF gentamicin concentrations, ventricle size, and daily output from ventricular drain. Duration is individualized according to clinical and microbiological response (Ref).
Intraventricular/intrathecal (use a preservative-free preparation):
Infants and Children: 1 to 2 mg/day.
Adolescents: Dosing recommendations not reported; however, in adults: 4 to 8 mg/day has been suggested.
Cystic fibrosis, pulmonary infection: Infants, Children, and Adolescents:
Conventional dosing: IM, IV: 3.3 mg/kg/dose every 8 hours (Ref).
Extended-interval dosing: IV: 10 to 12 mg/kg/dose every 24 hours (Ref); maximum reported dose from a survey of 28 Cystic Fibrosis (CF) Foundation-accredited centers ranged from 12 to 20 mg/kg/dose (Ref). Note: The CF Foundation recommends extended-interval dosing as preferred over conventional dosing.
Endocarditis, treatment:
Synergy dosing (eg, gram-positive bacteria): Children and Adolescents: IV: 3 to 6 mg/kg/day divided every 8 hours; use in combination with other antibiotics dependent on pathogen and source of infection (ie, valve type) (Ref).
Treatment dosing (eg, gram-negative bacteria): Children and Adolescents: IV: 7.5 mg/kg/day divided every 8 hours; use in combination with other antibiotics (Ref).
Gonococcal infection, uncomplicated infection of the cervix, urethra, or rectum (alternative agent for severe cephalosporin allergy): Limited data available:
Children ≥45 kg and Adolescents: IM: 240 mg once (administer as two 3 mL injections) in combination with single dose of oral azithromycin (Ref). Note: For treatment failure, consult an infectious diseases specialist and report to the CDC through state and local health departments within 24 hours of diagnosis (Ref).
Intra-abdominal infection, complicated: Infants, Children, and Adolescents: IV: 3 to 7.5 mg/kg/day divided every 8 to 24 hours; use in combination with other antibiotics (Ref).
Peritonitis (peritoneal dialysis) (Ref): Limited data available: Infants, Children, and Adolescents:
Intermittent: Intraperitoneal:
Anuric: 0.6 mg/kg/dose every 24 hours in the long dwell.
Nonanuric: 0.75 mg/kg/dose every 24 hours in the long dwell.
Continuous: Intraperitoneal: Loading dose: 8 mg per liter of dialysate; maintenance dose: 4 mg per liter.
Surgical prophylaxis: Infants, Children, and Adolescents: IV: 2.5 mg/kg as a single dose; administer within 60 minutes prior to surgical incision with or without other antibiotics (procedure dependent) (Ref).
Tularemia: Infants, Children, and Adolescents: IM, IV: 5 to 6 mg/kg/day in 2 to 3 divided doses (Ref); usual duration is 7 to 10 days; a shorter course (ie, 5 to 7 days) may be considered for mild disease; longer duration and concomitant antibiotics are required for severe illness (eg, meningitis) (Ref).
Urinary tract infection (UTI):
Note: Duration of therapy for multiple-dose regimens: For uncomplicated cystitis in patients ≥3 months of age, treat for 3 to 5 days; patients <2 years of age may require a longer course (eg, 7 days). For complicated UTI, including pyelonephritis, treat for a total of 6 to 10 days; while 7 to 14 days has been recommended for complicated UTI, this was not shown to improve outcomes compared to a shorter duration of 6 to 10 days (Ref).
Conventional dosing: Infants, Children, and Adolescents: IV: 7.5 mg/kg/day divided every 8 hours until clinical improvement and able to tolerate oral intake; complete course with oral antibiotics. Duration should be individualized based upon age, severity, and degree of urinary tract involvement.
Extended-interval dosing: Limited data available: Based on data from 90 patients (ages: 1 month to 12 years), the following age-directed dosing has been suggested (Ref): Note: Patients were transitioned to oral therapy once afebrile for 24 hours.
Infants and Children <5 years: IV: 7.5 mg/kg/dose every 24 hours.
Children 5 to 10 years: IV: 6 mg/kg/dose every 24 hours.
Children 11 to 12 years: IV: 4.5 mg/kg/dose every 24 hours.
Single-dose regimen: Limited data available: Note: Recommended for treatment of uncomplicated cystitis caused by antimicrobial resistant gram-negative pathogens (Ref):
Infants, Children, and Adolescents: IM: 5 mg/kg as a single dose; dosing based on 2 prospective studies evaluating single-dose IM gentamicin in patients 1 month to 15 years and a systematic review evaluating studies of various single-dose aminoglycosides in pediatric and adult patients (Ref); one study limited doses to 300 mg (Ref). An overall pooled cure rate for single dose IM aminoglycoside for treatment of children and adults with mainly uncomplicated cystitis was reported as 94.5% ± 4.3% (Ref). Note: Guidelines do not address pediatric dosing; recommended aminoglycoside doses in adults include IV single doses (Ref).
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
Parenteral: Note: Gentamicin serum concentrations should be monitored in patients with kidney impairment; following the initial dose, subsequent doses may be determined based on therapeutic monitoring.
Infants, Children, and Adolescents: IM, IV:
The following adjustments have been recommended (Ref): Note: Renally adjusted dose recommendations are based on doses of 2.5 mg/kg/dose every 8 hours:
GFR >50 mL/minute/1.73 m2: No dosage adjustment necessary.
GFR 30 to 50 mL/minute/1.73 m2: Administer every 12 to 18 hours.
GFR 10 to 29 mL/minute/1.73 m2: Administer every 18 to 24 hours.
GFR <10 mL/minute/1.73 m2: Administer every 48 to 72 hours.
Intermittent hemodialysis: 2 mg/kg/dose; redose as indicated by serum concentration.
Peritoneal dialysis (PD): 2 mg/kg/dose; redose as indicated by serum concentration.
Continuous renal replacement therapy (CRRT): 2 to 2.5 mg/kg/dose every 12 to 24 hours, monitor serum concentrations.
There are no dosage adjustments provided in the manufacturer's labeling; however, dosage adjustment not likely to be necessary (does not undergo hepatic metabolism).
(For additional information see "Gentamicin (systemic): Drug information")
Dosage guidance:
Dosing: For patients who are underweight (ie, total body weight [TBW] < ideal body weight [IBW]), calculate the dose based on TBW. For patients who are nonobese (ie, TBW 1 to 1.25 × IBW), calculate the dose based on TBW or IBW. TBW may be preferred in patients who are nonobese who may have increased Vd (eg, critically ill). For patients with obesity (ie, TBW >1.25 x IBW), use adjusted body weight ([0.4 x {TBW-IBW}] + IBW) for initial weight-based dosing and for estimating kidney function with Cockcroft-Gault (CrCl) (Ref).
Clinical considerations: Therapeutic drug monitoring is recommended to ensure efficacy and avoid toxicity, particularly in patients who are critically ill with serious infections or in disease states known to significantly alter aminoglycoside pharmacokinetics (eg, cystic fibrosis, burns, major surgery). Timing and frequency of concentration monitoring is individualized based on dosing and monitoring strategy (Ref).
Usual dosage range:
Gram-negative infections:
Conventional/traditional dosing: IV, IM: 3 to 5 mg/kg/day in divided doses every 8 hours (Ref). Some experts favor an initial loading dose of 2.5 to 3 mg/kg (Ref). Target peak concentration depends on indication and site of infection; in general, adjust dose to achieve peak of 4 to 6 mcg/mL for urinary tract infections and 7 to 10 mcg/mL for serious infections (including life-threatening infections). Target trough concentrations should be <2 mcg/mL; ideal target <1 mcg/mL (Ref).
High-dose extended-interval dosing (once-daily dosing): IV: 5 to 7 mg/kg once daily; use with caution in patients with CrCl <40 mL/minute (Ref). Adjust gentamicin dose and interval to achieve an extrapolated peak concentration of ~15 to 20 mcg/mL and trough concentration ≤0.5 mcg/mL (Ref). Note: Published nomograms for dosage adjustment may not apply to patients with altered pharmacokinetics (eg, patients with ascites, burns covering >20% total BSA, end-stage renal disease requiring hemodialysis, pregnancy) (Ref); some experts prefer traditional intermittent dosing in such populations (Ref).
Synergy dosing for non-CNS gram-positive infections:
IV, IM: 3 mg/kg/day in 1 to 3 divided doses in combination with a gram-positive active agent (Ref). When divided doses are used, adjust gentamicin dose to achieve peak concentration of 3 to 4 mcg/mL and trough concentration <1 mcg/mL (Ref).
Bartonella spp. infection (off-label use):
Bacteremia with or without endocarditis: IV: 3 mg/kg/day in 1 or 3 divided doses in combination with doxycycline for 2 weeks, followed by doxycycline monotherapy (Ref). Some experts do not suggest gentamicin as part of the regimen for patients with HIV and bacteremia without endocarditis (Ref).
Cat scratch disease, disseminated (eg, hepatosplenic, prolonged systemic febrile illness) (alternative agent): IV: 3 mg/kg once daily in combination with rifampin for 10 to 14 days (Ref).
Note: In contrast to other gram-negative infections, target a gentamicin peak concentration of 3 to 4 mcg/mL and trough concentration of <1 mcg/mL when divided doses are used (Ref).
Bloodstream infection:
Adjunctive empiric therapy for patients with sepsis/septic shock and concern for resistant gram-negative bacteria (eg, immunosuppression, prevalent local resistance, recent antibiotic exposure): IV: 5 to 7 mg/kg once daily in combination with a second gram-negative active agent; once culture and susceptibility results are available, can generally discontinue and use a single agent with documented activity. Gentamicin should not be used as monotherapy (Ref).
Antibiotic lock technique (catheter-salvage strategy) (off-label use): Note: For infections caused by susceptible organisms when the catheter cannot be removed; use in addition to systemic antibiotics (Ref).
Intracatheter: Prepare lock solution to final concentration of gentamicin 1 to 5 mg/mL (may be combined with heparin) (Ref). The gentamicin concentration may vary by institution, catheter type, and whether heparin is utilized; solutions with heparin are preferred. Prepare solution immediately before instillation with a sufficient volume to fill the catheter (2 to 5 mL). Instill into each lumen of the catheter access port with a dwell time of up to 72 hours, depending on frequency of catheter use. Withdraw lock solution prior to catheter use; replace with fresh gentamicin lock solution after catheter use. Antibiotic lock therapy is given for the same duration as systemic antibiotics (Ref).
Brucellosis (off-label use):
Note: Additional agents or other regimens are preferred for neurobrucellosis and infection in patients who are pregnant (Ref).
Endocarditis: IV, IM: 5 mg/kg/day in 1 to 3 divided doses for 4 weeks as part of an appropriate combination regimen (Ref).
Spondylitis: IV, IM: 5 mg/kg once daily for 7 to 14 days as part of an appropriate combination regimen (Ref).
Uncomplicated (nonfocal): IV, IM: 5 mg/kg once daily for 7 to 10 days as part of an appropriate combination regimen (Ref).
CNS infection, health care–associated (eg, cerebrospinal fluid [CSF] shunt infection) (adjunct to systemic therapy):
Note: Reserved for infections due to multidrug-resistant organisms, infections refractory to appropriate parenteral therapy, or when infected shunts cannot be removed (Ref).
Intraventricular (use a preservative-free preparation): Initial: 4 to 8 mg/day; some experts recommend adjusting dosage and administration interval based on CSF gentamicin concentrations (goal: 10 to 20 times MIC of causative organism), ventricle size, and daily output from ventricular drain (Ref). When intraventricular gentamicin is administered via a ventricular drain, clamp drain for 15 to 60 minutes after administration (allows solution to equilibrate in CSF). Duration is individualized according to clinical and microbiologic response (Ref).
Endocarditis, treatment:
Enterococcus spp. (native or prosthetic valve, without high-level gentamicin resistance): IV, IM: 1 mg/kg every 8 hours as part of an appropriate combination regimen. Duration is 4 to 6 weeks depending on duration of symptoms prior to presentation, source of infection, and the specific combination regimen (Ref). Note: For native-valve endocarditis due to ampicillin-susceptible Enterococcus faecalis, some experts prefer a combination regimen that does not contain gentamicin (Ref).
Staphylococcus spp. (prosthetic valve) (off-label use): IV, IM: 1 mg/kg every 8 hours for the first 2 weeks of an appropriate combination regimen; the other components should be continued for a total of ≥6 weeks (Ref).
Viridans group streptococci and Streptococcus bovis (off-label use):
Native valve: Highly penicillin-susceptible (MIC ≤0.12 mcg/mL): IV, IM: 3 mg/kg/day once daily (preferred) or in 3 divided doses (alternative) in combination with a beta-lactam for 2 weeks. Note: This regimen is reserved for patients with uncomplicated infection, prompt response to therapy, and no preexisting renal failure (Ref).
Native valve: Relatively penicillin-resistant (MIC >0.12 and <0.5 mcg/mL): IV, IM: 3 mg/kg/day once daily (preferred) or in 3 divided doses (alternative) in combination with a beta-lactam. Gentamicin duration is for the first 2 weeks of the total 4-week regimen (Ref).
Native valve: Penicillin-resistant (MIC ≥0.5 mcg/mL): IV, IM: 3 mg/kg/day in 2 to 3 divided doses in combination with a beta-lactam. The duration of this regimen is not well established; infectious diseases consultation recommended (Ref).
Prosthetic valve: Highly penicillin-susceptible (MIC ≤0.12 mcg/mL): IV, IM: 3 mg/kg/day once daily (preferred) or in 3 divided doses (alternative) in combination with a beta-lactam. Gentamicin duration is for the first 2 weeks of the total 6-week regimen (Ref).
Prosthetic valve: Relatively penicillin-resistant (MIC >0.12 and <0.5 mcg/mL) or fully penicillin-resistant (MIC ≥0.5 mcg/mL): IV, IM: 3 mg/kg/day once daily or in 3 divided doses in combination with a beta-lactam for 6 weeks (Ref); some experts prefer 3 divided doses for these isolates and also prefer shorter courses of the gentamicin component (≥2 weeks) for relatively penicillin-resistant strains (Ref).
Meningitis, bacterial:
Enterococcus spp.: IV: 5 mg/kg/day in 1 or 3 divided doses (Ref); give as part of an appropriate combination regimen and individualize duration based on clinical response (Ref).
Listeria monocytogenes: IV: 5 mg/kg/day in 3 divided doses in combination with ampicillin or penicillin. Gentamicin is given until clinical improvement (typically ≥7 days) or in poor responders for up to 21 days, as long as there are no signs of nephrotoxicity or ototoxicity; total duration of antibiotic therapy is ≥21 days (Ref).
Osteomyelitis, prevention, following open fractures (type III [severe contamination or comminution]) (off-label use): IV: 5 mg/kg every 24 hours as part of an appropriate combination regimen. Duration is 72 hours after injury or up to 24 hours after wound closure (Ref).
Pelvic infections (off-label use):
Note: Dose is based on actual body weight. For patients >1.2 × IBW, use adjusted body weight (IBW + [0.4 × (TBW-IBW)]) (Ref).
Intra-amniotic infection (chorioamnionitis): IV: 5 mg/kg once daily (preferred) or 2 mg/kg loading dose followed by 1.5 mg/kg every 8 hours (alternative); give in combination with ampicillin. In women undergoing cesarean delivery, an anti-anaerobic agent should also be added. Continue regimen until vaginal delivery or for 1 dose after cesarean delivery (Ref). Note: Some experts recommend 1 additional dose after vaginal delivery and extension of antibiotics after cesarean delivery until patient is afebrile and asymptomatic ≥48 hours (Ref).
Postpartum endometritis: IV: 5 mg/kg once daily (preferred) or 1.5 mg/kg every 8 hours (alternative) in combination with clindamycin. Treat until the patient is clinically improved (no fundal tenderness) and afebrile for 24 to 48 hours (Ref). Note: For women with group B Streptococcus colonization or sepsis, additional agents or other regimens are preferred (Ref).
Peritonitis, treatment (peritoneal dialysis) (off-label route):
Note: Intraperitoneal administration is preferred to IV administration unless the patient has sepsis (Ref).
Intermittent: Intraperitoneal: 0.6 mg/kg added to the dialysate solution once daily; allow to dwell ≥6 hours. Once culture results are available, if possible, switch to another active antibiotic class to decrease the risk of toxicity; otherwise, for patients with adequate clinical response, duration of therapy is ≥3 weeks. Prolonged courses (>7 days) of gentamicin are generally not recommended. For patients with no improvement after 5 days, remove catheter and treat with appropriate systemic antibiotics for 14 days after catheter removal (Ref).
Plague ( Yersinia pestis ), treatment (off-label use):
Note: Consult public health officials for event-specific recommendations.
IV, IM: 5 mg/kg once daily for 7 to 14 days and for at least a few days after clinical resolution (Ref).
Sepsis or septic shock, adjunctive empiric gram-negative coverage (eg, in the setting of intra-abdominal infection, pneumonia, gram-negative bacteremia, or severe burn):
Note: Some experts reserve for patients with immunocompromising conditions or risk for resistant gram-negative pathogens, in particular Pseudomonas aeruginosa (Ref).
IV: 5 to 7 mg/kg once daily in combination with a second gram-negative agent (Ref); once culture and susceptibility tests are available, can generally discontinue and use a single agent with documented activity. Gentamicin should not be used as monotherapy for severe infections outside of the urinary tract (Ref).
Sexually transmitted infections:
Gonococcal infection, uncomplicated (infection of the cervix, rectum, or urethra) (alternative agent) (off-label use):
Note: Reserve for patients who cannot use a cephalosporin (Ref).
>45 kg: IM: 240 mg (administer as two 3 mL injections) once (Ref).
≤45 kg: IM: 5 mg/kg once (Ref).
Administer in combination with oral azithromycin 2 g, each as a single dose (Ref). When treatment failure is suspected (eg, detection of Neisseria gonorrhoeae after treatment without additional sexual exposure), consult an infectious diseases specialist. Report failures to the CDC through state and local health departments (Ref).
Pelvic inflammatory disease, severe (including tubo-ovarian abscess) (alternative agent) (off-label use): IV, IM: 3 to 5 mg/kg once daily or 2 mg/kg as a loading dose followed by 1.5 mg/kg every 8 hours; give as part of an appropriate combination regimen; after 24 to 48 hours of sustained clinical improvement, transition to oral therapy to complete 14 days of treatment (Ref). Note: Some experts reserve this regimen for patients who cannot use preferred agents due to greater associated adverse effects (Ref).
Surgical prophylaxis (alternative agent for select GI tract, GU tract, or gynecologic/obstetric procedures) (off-label use):
IV: 5 mg/kg as a single dose within 60 minutes prior to surgical incision; give in combination with other antibiotics (procedure dependent) (Ref). Note: In cases where extension of prophylaxis is warranted postoperatively, total duration should be ≤24 hours (Ref). Postoperative prophylaxis is not recommended in clean and clean-contaminated surgeries (Ref).
Urinary tract infection (alternative agent):
Note: Reserve use for when other agents cannot be used (eg, resistant gram-negative infection) (Ref).
Cystitis, acute uncomplicated or acute simple cystitis (infection limited to bladder without signs/symptoms of upper tract, prostate, or systemic infection): IV: 5 mg/kg once (Ref).
Urinary tract infection, complicated (pyelonephritis or urinary tract infection with systemic signs/symptoms):
Inpatients: IV, IM: 5 to 7 mg/kg once daily (Ref). Switch to an appropriate oral regimen once symptoms improve, if culture and susceptibility results allow. Total duration of therapy ranges from 5 to 14 days; for patients with symptomatic improvement within the first 48 to 72 hours of therapy, some experts recommend shorter courses of 5 to 10 days (Ref).
Outpatients: IV, IM: 5 to 7 mg/kg once, followed by 5 to 10 days of appropriate oral therapy (Ref).
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
The renal dosing recommendations are based upon the best available evidence and clinical expertise. Senior Editorial Team: Bruce Mueller, PharmD, FCCP, FASN, FNKF; Jason A. Roberts, PhD, BPharm (Hons), B App Sc, FSHP, FISAC; Michael Heung, MD, MS.
Altered kidney function:
High-dose, extended-interval dosing:
Note: Use with caution in patients with CrCl <40 mL/minute (Ref); high-dose, extended-interval dosing may still be considered, especially in patients with severe sepsis/shock or those infected with multidrug-resistant gram-negative organisms (Ref).
IV: Initial dose: 5 to 7 mg/kg. Subsequent doses and frequency of administration should be determined based on therapeutic drug monitoring; regimens may vary; nomograms exist to guide dose adjustments, although individualized calculations may be necessary in patients with highly variable or altered aminoglycoside pharmacokinetics (eg, critical illness, pregnancy) (Ref). Also refer to institutional-specific policies. The following recommendations may serve as a general guideline after the initial dose:
CrCl ≥60 mL/minute: IV: Administer every 24 hours; adjust dose and/or interval based on gentamicin serum concentrations.
CrCl 40 to <60 mL/minute: IV: Administer every 36 hours; adjust dose and/or interval based on gentamicin serum concentrations.
CrCl 20 to <40 mL/minute: IV: Administer every 48 hours; adjust dose and/or interval based on gentamicin serum concentrations.
CrCl <20 mL/minute: IV: Administer usual dose once, then determine subsequent dose and interval based on serum concentration monitoring. Some published protocols would recommend conventional/traditional dosing in these patients (Ref).
Conventional/traditional dosing:
Note: High-dose, extended-interval dosing is generally preferred for treatment of gram-negative infections. Conventional/traditional dosing is typically used for synergy dosing or non-CNS, gram-positive infections.
Regimens may vary based on individualized pharmacokinetic calculations and pharmacodynamic targets; also refer to institutional-specific policies. Note: The following recommendations are expert opinion derived from Leroy 1978 and based on a usual dosage range of 3 to 5 mg/kg/day:
CrCl ≥60 mL/minute: IM, IV: No dosage adjustment necessary.
CrCl ≥40 to <60 mL/minute: IM, IV: Administer usual dose every 12 hours; adjust dose and/or interval based on gentamicin serum concentrations.
CrCl 20 to <40 mL/minute: IM, IV: Administer usual dose every 24 hours; adjust dose and/or interval based on gentamicin serum concentrations.
CrCl <20 mL/minute: IM, IV: Administer usual dose every 36 to 48 hours; adjust dose and/or interval based on gentamicin serum concentrations.
Augmented renal clearance (measured urinary CrCl ≥130 mL/minute/1.73 m2):
Note: Augmented renal clearance (ARC) is a condition that occurs in certain critically ill patients without organ dysfunction and with normal serum creatinine concentrations. Young patients (<55 years of age) admitted post trauma or major surgery are at highest risk for ARC, as well as those with sepsis, burns, or hematologic malignancies. An 8- to 24-hour measured urinary CrCl is necessary to identify these patients (Ref).
High-dose, extended-interval dosing: IV: Initial: 7 to 8 mg/kg once daily for known/suspected sepsis; adjust dose and/or interval based on close monitoring of gentamicin serum concentrations and individualized pharmacokinetic calculations and pharmacodynamic targets; use of nomograms for dosage adjustment are not recommended in this population (Ref).
Hemodialysis, intermittent (thrice weekly): Dialyzable (~50%; dependent on filter and duration): Note: Postdialysis concentrations should be drawn ≥2 and up to 4 hours after hemodialysis (HD) to allow for redistribution (Ref).
Loading dose of 2 to 3 mg/kg followed by:
Gram-positive synergy dosing: IM, IV: 1 mg/kg/dose 3 times weekly after dialysis on dialysis days (Ref); consider redosing for pre-HD or post-HD concentrations <1 mg/L.
Urinary tract infection: IM, IV: 1 to 1.5 mg/kg/dose 3 times weekly after dialysis on dialysis days (Ref); consider redosing for pre-HD concentrations <1.5 to 2 mg/L or post-HD concentrations <1 mg/L.
Systemic gram-negative infection: IM, IV: 2 to 3 mg/kg/dose 3 times weekly after dialysis on dialysis days (Ref); consider redosing for pre-HD concentrations <3 to 5 mg/L or post-HD concentrations <2 mg/L.
Peritoneal dialysis: IM, IV: Initial: 1 to 3 mg/kg/dose (depending on infection site, severity, and susceptibility of infecting organisms) every 48 to 72 hours based on gentamicin serum concentrations (Ref).
CRRT:
Note: Drug clearance is dependent on the effluent flow rate, filter type, and method of renal replacement. Recommendations are based on high-flux dialyzers and effluent flow rates of 20 to 25 mL/kg/hour (or ~1,500 to 3,000 mL/hour) unless otherwise noted. Appropriate dosing requires consideration of adequate drug concentrations (eg, site of infection) and consideration of initial loading doses. Close monitoring of response and adverse reactions (eg, nephrotoxicity) due to drug accumulation is important.
CVVH/CVVHD/CVVHDF:
Gram-positive synergy dosing: IV: Loading dose of 2 to 3 mg/kg/dose followed by 1 to 1.5 mg/kg every 24 to 36 hours (redose when concentration <1 mg/L (Ref)).
Urinary tract infection: IV: Loading dose of 2 to 3 mg/kg/dose followed by 1 to 1.5 mg/kg every 24 to 36 hours (redose when concentration <1.5 to 2 mg/L (Ref)).
Systemic gram-negative infection: IV: Initial: 2.5 to 3 mg/kg/dose; up to 5 mg/kg/dose may be considered (depending on infection site, severity, and susceptibility of infecting organisms) every 24 to 48 hours based on gentamicin serum concentrations (expert opinion derived from Petejova 2012).
PIRRT (eg, sustained, low-efficiency diafiltration):
Note: Drug clearance is dependent on the effluent flow rate, filter type, and method of renal replacement. Appropriate dosing requires consideration of adequate drug concentrations (eg, site of infection) and consideration of initial loading doses. Close monitoring of response and adverse reactions (eg, nephrotoxicity) due to drug accumulation is important. Dosing below assumes daily use of PIRRT.
Gram-positive synergy dosing: IV: Loading dose of 2 to 3 mg/kg/dose followed by 1 to 1.5 mg/kg/dose every 24 to 36 hours; adjust dose and/or frequency based on gentamicin serum concentrations. When scheduled dose falls on a PIRRT day, administer after PIRRT (Ref).
Urinary tract infection: IV: Loading dose of 2 to 3 mg/kg/dose followed by 1 to 1.5 mg/kg/dose every 24 to 36 hours; adjust dose based on serum concentrations. When scheduled dose falls on a PIRRT day, administer after PIRRT (Ref).
Systemic gram-negative infection: IV: Initial: 6 mg/kg/dose every 48 hours; adjust interval if needed based on gentamicin levels (usual frequency is every 48 to 72 hours). Note: Administer each dose 30 to 60 minutes prior to PIRRT session on PIRRT days (Ref).
There are no dosage adjustments provided in the manufacturer’s labeling; however dosage adjustment is not likely to be necessary (does not undergo hepatic metabolism).
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified. Frequency not defined.
Cardiovascular: Edema, hypertension, hypotension, phlebitis, thrombophlebitis
Central nervous system: Abnormal gait, ataxia, brain disease, confusion, depression, dizziness, drowsiness, headache, lethargy, myasthenia, numbness, paresthesia, peripheral neuropathy, pseudomotor cerebri, seizure, vertigo
Dermatologic: Alopecia, erythema, pruritus, skin rash, urticaria
Endocrine & metabolic: Hypocalcemia, hypokalemia, hypomagnesemia, hyponatremia, weight loss
Gastrointestinal: Anorexia, Clostridioides difficile-associated diarrhea, decreased appetite, enterocolitis, nausea, sialorrhea, stomatitis, vomiting
Genitourinary: Casts in urine (hyaline, granular), Fanconi-like syndrome (infants and adults; high dose, prolonged course), oliguria, proteinuria
Hematologic & oncologic: Agranulocytosis, anemia, eosinophilia, granulocytopenia, leukopenia, purpura, reticulocytopenia, reticulocytosis, splenomegaly, thrombocytopenia
Hepatic: Hepatomegaly, increased liver enzymes
Hypersensitivity: Anaphylaxis, anaphylactoid reaction, hypersensitivity reaction
Local: Injection site reaction, pain at injection site
Neuromuscular & skeletal: Arthralgia, muscle cramps, muscle fatigue (myasthenia gravis-like syndrome), muscle twitching, tremor, weakness
Ophthalmic: Visual disturbance
Otic: Auditory impairment, hearing loss (associated with persistently increased serum concentrations; early toxicity usually affects high-pitched sound), tinnitus
Renal: Decreased creatinine clearance, decreased urine specific gravity, increased blood urea nitrogen, increased serum creatinine, polyuria, renal failure (high trough serum concentrations), renal tubular necrosis
Respiratory: Dyspnea, laryngeal edema, pulmonary fibrosis, respiratory depression
Miscellaneous: Fever
Hypersensitivity to gentamicin, other aminoglycosides, or any component of the formulation
Concerns related to adverse effects:
• Hypersensitivity: Cross-sensitivity to other aminoglycosides may occur.
• Nephrotoxicity: [US Boxed Warning]: May cause nephrotoxicity; usual risk factors include preexisting renal impairment, concomitant nephrotoxic medications, advanced age and dehydration. Discontinue treatment if signs of nephrotoxicity occur; renal damage is usually reversible.
• Neuromuscular blockade and respiratory paralysis: May cause neuromuscular blockade and respiratory paralysis; especially when given soon after anesthesia or neuromuscular blockers.
• Neurotoxicity: [US Boxed Warning]: May cause neurotoxicity; usual risk factors include preexisting renal impairment, concomitant neuro-/nephrotoxic medications, advanced age and dehydration. Ototoxicity is proportional to the amount of drug given and the duration of treatment. Tinnitus or vertigo may be indications of vestibular injury and impending bilateral irreversible damage. Discontinue treatment if signs of ototoxicity occur.
• Superinfection: Prolonged use may result in fungal or bacterial superinfection, including Clostridioides difficile-associated diarrhea (CDAD) and pseudomembranous colitis; CDAD has been observed >2 months postantibiotic treatment.
Disease-related concerns:
• Electrolyte abnormalities: Use with caution in patients with hypocalcemia, hypokalemia, or hypomagnesemia.
• Hearing impairment: Use with caution in patients with preexisting vertigo, tinnitus, or hearing loss.
• Neuromuscular disorders: Use with caution in patients with neuromuscular disorders, including myasthenia gravis.
• Renal impairment: Use with caution in patients with preexisting renal insufficiency; dosage modification required.
Special populations:
• Patients with genomic variants in MT-RNR1: Carriers of certain variants in the MT-RNR1 gene (eg, m.1555A>G) may be at increased risk for aminoglycoside-induced ototoxicity, including potentially significant hearing loss that may be irreversible, even when serum levels are within the normal range.
• Pregnancy: [US Boxed Warning]: Aminoglycosides may cause fetal harm if administered to a pregnant woman.
Concurrent drug therapy issues:
• Neurotoxic and/or nephrotoxic drugs: [US Boxed Warning]: Avoid concomitant or sequential use of other neurotoxic and/or nephrotoxic drugs (eg, cisplatin, polymyxin B, colistin, vancomycin, other aminoglycosides).
• Potent diuretics: [US Boxed Warning]: Avoid concomitant use with potent diuretics (eg, ethacrynic acid, furosemide) since diuretics themselves may cause ototoxicity and may enhance aminoglycoside toxicity.
Other warnings/precautions:
• Long-term use: Risk of toxicity is increased with extended duration of administration; additional monitoring may be required with long-term use.
• Surgical irrigation: May be almost completely systemically absorbed after local irrigation and/or topical application (except to the urinary bladder) during surgical procedures. Consider potential for nephrotoxicity, neuromuscular blockade, ototoxicity, and respiratory paralysis when administering aminoglycosides in this manner.
Use with caution in pediatric patients on extracorporeal membrane oxygenation (ECMO); pharmacokinetics of aminoglycosides may be altered; dosage adjustment and close monitoring necessary. Oral use for the prevention of NEC in premature neonates may potentially increase the risk for development of resistant bacteria; routine use for this is not recommended (Bury 2001; Reber 2004).
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Solution, Injection:
Generic: 40 mg/mL (2 mL, 20 mL)
Solution, Injection [preservative free]:
Generic: 10 mg/mL (2 mL); 40 mg/mL (2 mL, 20 mL)
Solution, Intravenous [preservative free]:
Generic: 60 mg (50 mL); 80 mg (50 mL, 100 mL); 100 mg (50 mL, 100 mL); 120 mg (100 mL)
Yes
Solution (Gentamicin Sulfate Injection)
10 mg/mL (per mL): $1.03 - $3.70
40 mg/mL (per mL): $0.73 - $2.79
Disclaimer: A representative AWP (Average Wholesale Price) price or price range is provided as reference price only. A range is provided when more than one manufacturer's AWP price is available and uses the low and high price reported by the manufacturers to determine the range. The pricing data should be used for benchmarking purposes only, and as such should not be used alone to set or adjudicate any prices for reimbursement or purchasing functions or considered to be an exact price for a single product and/or manufacturer. Medi-Span expressly disclaims all warranties of any kind or nature, whether express or implied, and assumes no liability with respect to accuracy of price or price range data published in its solutions. In no event shall Medi-Span be liable for special, indirect, incidental, or consequential damages arising from use of price or price range data. Pricing data is updated monthly.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Solution, Injection:
Generic: 10 mg/mL (2 mL); 40 mg/mL (2 mL, 20 mL)
Solution, Intravenous:
Generic: 80 mg (50 mL); 100 mg (100 mL)
Parenteral:
IM: May be administered undiluted.
IV: Administer as diluted solution by slow intermittent infusion over 30 to 120 minutes; usual infusion time is 30 to 60 minutes; consider longer infusion time (60 to 120 minutes) with high doses. Shorter infusion times (≤5 minutes) have been reported in pediatric patients, including preterm and term neonates, receiving ≤4 mg/kg/dose (Ref). Avoid infusing concomitantly with penicillins or cephalosporins if feasible; consult drug interactions database for more information.
Intrathecal/intraventricular: Use preservative-free preparations only; must be diluted prior to administration. No specific administration information available; it has been suggested that instillation of small volumes (<3 mL) over 1 to 2 minutes is safe (Ref). When administered through a ventricular drain, clamp drain for 15 to 60 minutes to allow gentamicin solution to equilibrate in the cerebrospinal fluid (CSF) (Ref).
IM: Administer undiluted. Gentamicin in NS is not intended for IM administration.
IV: Infuse over 30 to 120 minutes.
Some penicillins (eg, carbenicillin, ticarcillin, piperacillin) have been shown to inactivate aminoglycosides in vitro. This has been observed to a greater extent with tobramycin and gentamicin, while amikacin has shown greater stability against inactivation. Concurrent use of these agents may pose a risk of reduced antibacterial efficacy in vivo, particularly in the setting of profound renal impairment. However, definitive clinical evidence is lacking. If combination penicillin/aminoglycoside therapy is desired in a patient with renal dysfunction, separation of doses (if feasible), and routine monitoring of aminoglycoside levels, CBC, and clinical response should be considered.
Intraventricular (off-label route): Use preservative-free preparations only. When administered through a ventricular drain, clamp drain for 15 to 60 minutes before opening the drain to allow gentamicin solution to equilibrate in the cerebrospinal fluid (Ref).
Intraperitoneal (off-label route): May administer intermittently (1 exchange daily); allow to dwell ≥6 hours (Ref).
Store intact vials and premixed bags at 20°C to 25°C (68°F to 77°F). Protect from freezing. Stability information when diluted for infusion is not reported in the manufacturer’s labeling; refer to compatibility database for details.
Treatment of serious infections (eg, sepsis, meningitis, urinary tract infections, respiratory tract infections, peritonitis, bone infections, skin and soft tissue infections) caused by susceptible strains of the following microorganisms: Pseudomonas aeruginosa, Escherichia coli, Klebsiella, Proteus, Serratia, Enterobacter, Citrobacter, and Staphylococcus species (FDA approved in all ages); empiric treatment of sepsis, in combination with a penicillin antibiotic such as ampicillin (FDA approved in neonates); has also been used for the treatment of brucellosis, peritonitis in patients with peritoneal catheters, and tularemia and for prophylaxis of surgical site infections.
Gentamicin may be confused with gentian violet, kanamycin, vancomycin
The Institute for Safe Medication Practices (ISMP) includes this medication among its list of drug classes (epidural and intrathecal medications) which have a heightened risk of causing significant patient harm when used in error (High-Alert Medications in Acute Care Settings).
None known.
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program by clicking on the “Launch drug interactions program” link above.
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program
Agalsidase Alfa: Gentamicin (Systemic) may diminish the therapeutic effect of Agalsidase Alfa. Risk X: Avoid combination
Agalsidase Beta: Gentamicin (Systemic) may diminish the therapeutic effect of Agalsidase Beta. Management: Avoid concomitant use of gentamicin with agalsidase beta when possible as gentamicin could antagonize intracellular alpha-galactosidase activity. Risk D: Consider therapy modification
Aminoglycosides: May enhance the nephrotoxic effect of other Aminoglycosides. Aminoglycosides may enhance the neurotoxic effect of other Aminoglycosides. Risk X: Avoid combination
Amphotericin B: May enhance the nephrotoxic effect of Aminoglycosides. Amphotericin B may enhance the neurotoxic effect of Aminoglycosides. Risk C: Monitor therapy
Ataluren: May enhance the adverse/toxic effect of Aminoglycosides. Specifically, an increased risk of nephrotoxicity may occur with the concomitant use of ataluren and aminoglycosides. Risk X: Avoid combination
Bacillus clausii: Antibiotics may diminish the therapeutic effect of Bacillus clausii. Management: Bacillus clausii should be taken in between antibiotic doses during concomitant therapy. Risk D: Consider therapy modification
Bacitracin (Systemic): May enhance the nephrotoxic effect of Aminoglycosides. Bacitracin (Systemic) may enhance the neurotoxic effect of Aminoglycosides. Risk X: Avoid combination
BCG (Intravesical): Antibiotics may diminish the therapeutic effect of BCG (Intravesical). Risk X: Avoid combination
BCG Vaccine (Immunization): Antibiotics may diminish the therapeutic effect of BCG Vaccine (Immunization). Risk C: Monitor therapy
Bisphosphonate Derivatives: Aminoglycosides may enhance the hypocalcemic effect of Bisphosphonate Derivatives. Aminoglycosides may enhance the nephrotoxic effect of Bisphosphonate Derivatives. Risk C: Monitor therapy
Botulinum Toxin-Containing Products: Aminoglycosides may enhance the neuromuscular-blocking effect of Botulinum Toxin-Containing Products. Risk C: Monitor therapy
Capreomycin: May enhance the neuromuscular-blocking effect of Aminoglycosides. Risk C: Monitor therapy
CARBOplatin: May enhance the nephrotoxic effect of Aminoglycosides. Aminoglycosides may enhance the ototoxic effect of CARBOplatin. Especially with higher doses of carboplatin. Risk C: Monitor therapy
Cardiac Glycosides: Aminoglycosides may decrease the serum concentration of Cardiac Glycosides. This effect has only been demonstrated with oral aminoglycoside administration. Risk C: Monitor therapy
Cephalosporins: May enhance the nephrotoxic effect of Aminoglycosides. Cephalosporins may decrease the serum concentration of Aminoglycosides. Risk C: Monitor therapy
Cholera Vaccine: Antibiotics may diminish the therapeutic effect of Cholera Vaccine. Management: Avoid cholera vaccine in patients receiving systemic antibiotics, and within 14 days following the use of oral or parenteral antibiotics. Risk X: Avoid combination
CISplatin: May enhance the nephrotoxic effect of Aminoglycosides. CISplatin may enhance the neurotoxic effect of Aminoglycosides. Risk X: Avoid combination
Colistimethate: Aminoglycosides may enhance the nephrotoxic effect of Colistimethate. Aminoglycosides may enhance the neuromuscular-blocking effect of Colistimethate. Management: Avoid coadministration of colistimethate and aminoglycosides whenever possible due to the risk of nephrotoxicity and neuromuscular blockade. If coadministration cannot be avoided, monitor renal and neuromuscular function. Risk D: Consider therapy modification
Cyclizine: May enhance the ototoxic effect of Aminoglycosides. Risk C: Monitor therapy
CycloSPORINE (Systemic): Aminoglycosides may enhance the nephrotoxic effect of CycloSPORINE (Systemic). Risk C: Monitor therapy
Distigmine: Aminoglycosides may diminish the therapeutic effect of Distigmine. Risk C: Monitor therapy
Fecal Microbiota (Live) (Oral): May diminish the therapeutic effect of Antibiotics. Risk X: Avoid combination
Fecal Microbiota (Live) (Rectal): Antibiotics may diminish the therapeutic effect of Fecal Microbiota (Live) (Rectal). Risk X: Avoid combination
Foscarnet: May enhance the nephrotoxic effect of Aminoglycosides. Risk X: Avoid combination
Immune Checkpoint Inhibitors (Anti-PD-1, -PD-L1, and -CTLA4 Therapies): Antibiotics may diminish the therapeutic effect of Immune Checkpoint Inhibitors (Anti-PD-1, -PD-L1, and -CTLA4 Therapies). Risk C: Monitor therapy
Lactobacillus and Estriol: Antibiotics may diminish the therapeutic effect of Lactobacillus and Estriol. Risk C: Monitor therapy
Loop Diuretics: May enhance the adverse/toxic effect of Aminoglycosides. Specifically, nephrotoxicity and ototoxicity. Risk C: Monitor therapy
Mannitol (Systemic): May enhance the nephrotoxic effect of Aminoglycosides. Risk X: Avoid combination
Mecamylamine: Aminoglycosides may enhance the neuromuscular-blocking effect of Mecamylamine. Risk X: Avoid combination
Methoxyflurane: Aminoglycosides may enhance the nephrotoxic effect of Methoxyflurane. Risk X: Avoid combination
Mycophenolate: Antibiotics may decrease serum concentrations of the active metabolite(s) of Mycophenolate. Specifically, concentrations of mycophenolic acid (MPA) may be reduced. Risk C: Monitor therapy
Netilmicin (Ophthalmic): Aminoglycosides may enhance the nephrotoxic effect of Netilmicin (Ophthalmic). Risk X: Avoid combination
Neuromuscular-Blocking Agents: Aminoglycosides may enhance the therapeutic effect of Neuromuscular-Blocking Agents. Risk C: Monitor therapy
Nonsteroidal Anti-Inflammatory Agents: May decrease the excretion of Aminoglycosides. Data only in premature infants. Risk C: Monitor therapy
Oxatomide: May enhance the ototoxic effect of Aminoglycosides. Risk C: Monitor therapy
Penicillins: May decrease the serum concentration of Aminoglycosides. Primarily associated with extended spectrum penicillins, and patients with renal dysfunction. Risk C: Monitor therapy
Polymyxin B: May enhance the nephrotoxic effect of Aminoglycosides. Polymyxin B may enhance the neurotoxic effect of Aminoglycosides. Risk X: Avoid combination
Sodium Picosulfate: Antibiotics may diminish the therapeutic effect of Sodium Picosulfate. Management: Consider using an alternative product for bowel cleansing prior to a colonoscopy in patients who have recently used or are concurrently using an antibiotic. Risk D: Consider therapy modification
Tacrolimus (Systemic): Aminoglycosides may enhance the nephrotoxic effect of Tacrolimus (Systemic). Risk C: Monitor therapy
Tenofovir Products: Aminoglycosides may increase the serum concentration of Tenofovir Products. Tenofovir Products may increase the serum concentration of Aminoglycosides. Risk C: Monitor therapy
Typhoid Vaccine: Antibiotics may diminish the therapeutic effect of Typhoid Vaccine. Only the live attenuated Ty21a strain is affected. Management: Avoid use of live attenuated typhoid vaccine (Ty21a) in patients being treated with systemic antibacterial agents. Postpone vaccination until 3 days after cessation of antibiotics and avoid starting antibiotics within 3 days of last vaccine dose. Risk D: Consider therapy modification
Vancomycin: May enhance the nephrotoxic effect of Aminoglycosides. Vancomycin may enhance the neurotoxic effect of Aminoglycosides. Management: Consider avoiding coadministration of aminoglycosides and vancomycin unless clinically indicated. If coadministered, monitor closely for signs of nephrotoxicity and neurotoxicity. Risk D: Consider therapy modification
Gentamicin crosses the placenta.
Aminoglycosides may cause fetal harm if administered to a pregnant patient. There are several reports of total irreversible bilateral congenital deafness in children whose mothers received another aminoglycoside (streptomycin) during pregnancy. Although serious side effects to the fetus/infant have not been reported following maternal use of all aminoglycosides, a potential for harm exists.
Due to pregnancy-induced physiologic changes, some pharmacokinetic parameters of gentamicin may be altered (Popović 2007).
Gentamicin use has been evaluated for various infections in pregnant patients including the treatment of acute pyelonephritis (Jolley 2010) and as an alternative antibiotic for prophylactic use prior to cesarean delivery (Bratzler 2013).
Gentamicin is used in the management of plague (Yersinia pestis). Untreated infections in pregnant patients may result in hemorrhage (including postpartum hemorrhage), maternal and fetal death, preterm birth, and stillbirth. Limited data suggest maternal-fetal transmission of Y. pestis can occur if not treated. Pregnant patients should be treated for Y. pestis; parenteral antibiotics are preferred for initial treatment when otherwise appropriate. Gentamicin (in combination with a fluoroquinolone) is recommended for treating pregnant patients with bubonic, pharyngeal, pneumonic, or septicemic plague (CDC [Nelson 2021]).
Urinalysis, urine output, BUN, SCr, hearing test (especially for those at risk for ototoxicity or who will be receiving prolonged therapy [>2 weeks]).
Serum gentamicin concentrations:
Conventional dosing: Initial serum concentrations typically obtained after the third dose; may consider obtaining serum concentrations sooner in neonates or patients with rapidly changing renal function.
Extended-interval dosing: Initial serum concentrations may be obtained following the first or second dose (Begg 1999; Knoderer 2003).
Patients receiving outpatient therapy: Serum gentamicin concentrations (at least weekly); CBC with differential (weekly); basic metabolic panel including potassium, creatinine, and BUN (twice weekly) (IDSA [Norris 2019]).
Not all pediatric patients who receive aminoglycosides require monitoring of serum aminoglycoside concentrations. Indications for use of aminoglycoside serum concentration monitoring include:
Treatment course >5 days.
Patients with decreased or changing renal function.
Patients with poor therapeutic response.
Neonates and Infants <3 months of age.
Atypical body constituency (obesity, expanded extracellular fluid volume).
Clinical need for higher doses or shorter intervals (eg, cystic fibrosis, burns, endocarditis, meningitis, critically ill patients, relatively resistant organism).
Patients on hemodialysis or chronic ambulatory peritoneal dialysis.
Signs of nephrotoxicity or ototoxicity.
Concomitant use of other nephrotoxic agents.
Some beta-lactam agents (penicillins and cephalosporins) may accelerate the degradation of aminoglycosides in vitro; this may be clinically significant in patients with significant renal impairment. Close monitoring of aminoglycoside concentrations and clinical response is warranted.
Note: Sampling times and target concentrations provided reflect general practices; patient-specific factors, including type and site of infection, goals of therapy, severity of illness, clinical status, fluid status, and kidney function should be considered when determining patient-specific therapeutic monitoring plans and targets. Outcomes are predicted by serum concentrations and the minimum inhibitory concentration (MIC) of the infecting organism. Efficacy has been associated with peak:MIC ratios of ≥8 to 10 and AUC24:MIC ratios of 30 to 100 depending on severity of infection (Bland 2018; Craig 2011; Knoderer 2003). Nephrotoxicity is associated with elevated trough concentrations (Bertino 1993; Rybak 1999). Some recommendations are based on tobramycin:
Neonates:
Timing of serum samples (El-Chaar 2016; Touw 2009; van Donge 2018; van Maarseveen 2016; manufacturer's labeling):
Peak: 30 minutes after end of 30-minute infusion, or 1 hour following start of infusion or IM injection.
Trough: End of dosing interval, just prior to the next dose.
Target concentrations: Note: Studies evaluating extended-interval dosing in neonates typically target concentrations more often associated with conventional dosing (Miller 2014).
Peak: ≥8 to 12 mg/L; 10 x MIC (El-Chaar 2016; Touw 2009; van Maarseveen 2016).
Trough: <0.5 to 1 mg/L (Touw 2009; van Maarseveen 2016).
Infants, Children, and Adolescents:
Conventional dosing:
Timing of serum samples:
Peak: 30 minutes after 30-minute infusion, or 1 hour following start of infusion or IM injection.
Trough: End of dosing interval, immediately before next dose.
Target concentrations:
Peak:
General: 6 to 12 mg/L or 10 x MIC (Red Book [AAP 2021]). Note: Peak concentrations on the lower end of the range would only achieve efficacy target (10 x MIC) for MICs ≤0.5 mg/L.
Urinary tract infections: 4 to 6 mg/L (Matzke 1983).
Synergy against gram-positive organisms: 3 to 4 mg/L (AHA [Baltimore 2015]).
Trough:
General: <1 to 2 mg/L (Hammett-Stabler 1998; Red Book [AAP 2021]); others suggest a target of <0.5 to 1 mg/L (Bland 2018; Touw 2009).
Synergy against gram-positive organisms: <1 mg/L (AHA [Baltimore 2015]).
Extended-interval dosing: Note: Monitoring protocols are not standardized; various approaches exist. In addition to the strategies discussed, AUC monitoring has also been described (Begg 1999; Bland 2018; Roy 2016).
Timing of serum samples:
Peak: 30 minutes after the end of a 30-minute infusion (Jenh 2011; Knoderer 2003). Some suggest waiting ≥60 minutes after the end of the infusion to allow time for distribution of higher doses and using patient-specific pharmacokinetic parameters to back-extrapolate true peak concentration (Prescott 2010; Safi 2016). It is not always necessary to monitor peak concentration depending on clinical situation (Begg 1999; Jenh 2011).
Trough: Obtain at the end of a dosing interval, just prior to the next dose (Begg 1999; Knoderer 2003). May also obtain 4 hours prior to the next dose to ensure that drug has cleared (McDade 2010).
Patient-specific calculations: Two concentrations at least 1 half-life apart can be obtained (eg, a peak and a mid-interval concentration 8 to 12 hours after the dose, or 2 postdistribution concentrations while drug is still detectable) to calculate patient-specific pharmacokinetic parameters and extrapolate peak, trough, AUC, and/or drug-free interval (Jenh 2011; Knoderer 2003). For patients with cystic fibrosis, the 2 random samples postinfusion method is the most common strategy used to monitor aminoglycosides (eg, obtain a serum concentration 2 hours and 8 to 10 hours after the start of the infusion, calculate elimination rate, and extrapolate peak and trough) (Zobell 2016).
Target concentrations:
Patients without cystic fibrosis:
Peak: 8 to 10 x MIC of the pathogen (~15 to 35 mg/L) (Jenh 2011; Knoderer 2003; Roy 2016).
Trough: <0.5 to 1 mg/L; ideally undetectable; a drug-free period is desired (Jenh 2011; Knoderer 2003; McDade 2010).
Patients with cystic fibrosis:
Peak: 20 to 30 mg/L (Safi 2016; Smyth 2005); target range variable; higher target concentrations up to 40 mg/L have been reported (Flume 2009; Zobell 2016). May be necessary to modify target based on MIC to achieve targets associated with efficacy (Burkhardt 2006).
Trough: <0.5 to 1 mg/L; undetectable (Flume 2009; Safi 2016; Wassil 2008; Zobell 2016). A drug-free period is desired; some centers adjust dose to provide a drug-free interval of ≤8 to 12 hours (Zobell 2016).
AUC: 75 to 125 mg•hour/L; most centers target 80 to 120 mg•hour/L (Zobell 2016).
Interferes with bacterial protein synthesis by binding to 30S ribosomal subunit resulting in a defective bacterial cell membrane
Absorption: IM: Rapid and complete; Oral: Poorly absorbed (<1%) (MacDougall 2011).
Distribution: Primarily into extracellular fluid (highly hydrophilic); high concentration in the renal cortex; minimal penetration to CSF and ocular tissues via IV route.
Vd: Varies with age; increased by edema, ascites, fluid overload; decreased with dehydration:
Neonates: 0.45 ± 0.1 L/kg.
Infants: 0.4 ± 0.1 L/kg.
Children: 0.35 ± 0.15 L/kg.
Adolescents: 0.3 ± 0.1 L/kg.
Adults: 0.2 to 0.3 L/kg (Leggett 2015; Xuan 2004).
CSF:blood level ratio: Normal meninges: <10%; Inflamed meninges: ≤25% (MacDougall 2011)
Lung:
Bronchial secretion Cmax (peak): serum Cmax (peak) ratio: ~50%, varies with time and route (IM vs IV) (Pennington 1975).
Epithelial lining fluid Cmax (peak): serum Cmax (peak) ratio: ~32%, varies with time (Heffernan 2019; Panidis 2005; Rodvold 2011).
Protein binding: <30%.
Half-life elimination:
Neonates: <1 week: 3 to 11.5 hours; 1 week to 1 month: 3 to 6 hours.
Infants: 4 ± 1 hour.
Children: 2 ± 1 hour.
Adolescents: 1.5 ± 1 hour.
Adults: ~2 hours (Regamey 1973); Renal failure: mean: 41 ± 24 hours; Range: 6 to 127 hours (Dager 2006).
Time to peak, serum: IM: 30 to 90 minutes; IV: 30 minutes after 30-minute infusion (MacDougall 2011); Note: Distribution is prolonged after larger doses (≥90 minutes after 30- to 60-minute infusion of 7 mg/kg) (Demczar 1997; McNamara 2001; Wallace 2002).
Excretion: Urine (≥70% as unchanged drug).
Clearance: Directly related to renal function.
Neonates: 0.045 ± 0.01 L/hour/kg.
Infants: 0.1 ± 0.05 L/hour/kg.
Children: 0.1 ± 0.03 L/hour/kg.
Adolescents: 0.09 ± 0.03 L/hour/kg.
Adults: 0.06 L/hour/kg (Xuan 2004).
Altered kidney function: Clearance is decreased in renal impairment.
Anti-infective considerations:
Parameters associated with efficacy: Gram-negative bacilli: Concentration-dependent; associated with Cmax (peak)/minimum inhibitory concentration (MIC), goal: ≥8 to 10 (IDSA [Tamma 2023]; Kashuba 1999; Moore 1987; Zelenitsky 2003) or AUC24/MIC, goal: 30 to 50 (mild/moderate infection, immunocompetent patient) or 80 to 100 (severe or resistant infection) (Bland 2018; Craig 2011; Drusano 2007; IDSA [Tamma 2023]; Nielsen 2011).
Expected drug exposure in patients with normal renal function:
Cmax (peak), postdistributional:
Infants, children, and adolescents (varies with age; values are generalized):
Neutropenic fever: 7 mg/kg: ~17 mg/L (Shankar 1999).
Critically ill: 7 to 8 mg/kg: 15 to 22 mg/L (Lopez 2010).
1.5 to 2.5 mg/kg: ~5 to 6 mg/L (Alsultan 2019; Knoderer 2003).
Adults:
7 mg/kg: ~22 mg/L (Finnell 1998; Xuan 2004).
2 mg/kg: ~6 mg/L (Demczar 1997).
AUC24:
Children and adolescents:
Neutropenic fever: 7 to 8 mg/kg: ~45 to 80 mg•hour/L (Bialkowski 2016).
Adults:
7 mg/kg: ~70 to 110 mg•hour/L (Barclay 1995; Craig 2011; Finnell 1998).
Parameters associated with toxicity: Nephrotoxicity is associated with more frequent administration and elevated Cmin (trough) concentrations leading to renal accumulation (Bertino 1993; Rybak 1999; Verpooten 1989); AUC has also been found to be predictive (Rybak 1999).
Postantibiotic effect: Bacterial killing continues after gentamicin concentration drops below the MIC of targeted pathogen; generally ~0.5 to 12 hours, though the actual time of postantibiotic effect varies significantly based on multiple factors including organism, gentamicin Cmax (peak), and concomitant antimicrobial therapy (Craig 2011; Gudmundsson 1993; Lacy 1998; Urban 1997).
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