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- Gentamicin Sulfate
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Generic: 10 mg/mL (2 mL); 40 mg/mL (2 mL, 20 mL)
Solution, Injection [preservative free]:
Generic: 10 mg/mL (2 mL)
Generic: 60 mg (50 mL); 70 mg (50 mL); 80 mg (50 mL, 100 mL); 90 mg (100 mL); 100 mg (50 mL, 100 mL); 120 mg (100 mL); 10 mg/mL (6 mL, 8 mL, 10 mL)
- Antibiotic, Aminoglycoside
Interferes with bacterial protein synthesis by binding to 30S and 50S ribosomal subunits resulting in a defective bacterial cell membrane
Intramuscular: Rapid and complete; Oral: Poorly absorbed (<2%)
Primarily into extracellular fluid (highly hydrophilic); high concentration in the renal cortex; minimal penetration to CSF and ocular tissues via IV route; small amounts distribute into bile, sputum, saliva, and tears
Vd: Higher in neonates than older pediatric patients; 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: 0.2-0.3 L/kg
Relative diffusion from blood into CSF: Minimal even with inflammation
CSF:blood level ratio: Normal meninges: Nil; Inflamed meninges: 10% to 30%
Urine (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
Time to Peak
Serum: IM: 30-90 minutes; IV: 30 minutes after 30-minute infusion; Note: Distribution may be prolonged after larger doses. One study reported a 1.7-hour distribution period after a 60-minute, high-dose aminoglycoside infusion (Demczar 1997).
Neonates: <1 week: 3-11.5 hours; 1 week to 1 month: 3 to 6 hours
Infants: 4 ± 1 hour
Children: 2 ± 1 hour
Adolescents: 1.5 ± 1 hour
Adults: 1.5-3 hours; End-stage renal disease: 36-70 hours
Special Populations: Renal Function Impairment
Clearance is decreased in renal impairment.
Use: Labeled Indications
Treatment of susceptible bacterial infections, normally gram-negative organisms, including Pseudomonas, Proteus, Serratia, and gram-positive Staphylococcus; treatment of bone infections, respiratory tract infections, skin and soft tissue infections, as well as abdominal and urinary tract infections, and septicemia; treatment of infective endocarditis
Surgical (preoperative) prophylaxis
Hypersensitivity to gentamicin or other aminoglycosides
Individualization is critical because of the low therapeutic index.
In underweight and nonobese patients, use of total body weight (TBW) instead of ideal body weight for determining the initial mg/kg/dose is widely accepted (Nicolau, 1995). Ideal body weight (IBW) also may be used to determine doses for patients who are neither underweight nor obese (Gilbert, 2009).
Initial and periodic plasma drug levels (eg, peak and trough with conventional dosing, post dose level at a prespecified time with extended-interval dosing) should be determined, particularly in critically-ill patients with serious infections or in disease states known to significantly alter aminoglycoside pharmacokinetics (eg, cystic fibrosis, burns, or major surgery).
Usual dosage ranges:
Conventional: 1-2.5 mg/kg/dose every 8-12 hours; to ensure adequate peak concentrations early in therapy, higher initial dosage may be considered in selected patients when extracellular water is increased (edema, septic shock, postsurgical, or trauma)
Once daily: 4-7 mg/kg/dose once daily; some clinicians recommend this approach for all patients with normal renal function; this dose is at least as efficacious with similar, if not less, toxicity than conventional dosing
Intrathecal: 4-8 mg/day
Indication-specific dosing: IM, IV:
Brucellosis: 240 mg (IM) daily or 5 mg/kg (IV) daily for 7 days; either regimen recommended in combination with doxycycline
Cholangitis: 4-6 mg/kg once daily with ampicillin
Diverticulitis (complicated): 1.5-2 mg/kg every 8 hours (with ampicillin and metronidazole)
Enterococcus (native or prosthetic valve) (off-label dose): IV, IM: 3 mg/kg/day in 2 or 3 divided doses in combination with a beta-lactam or vancomycin (choice of concomitant antibiotic and treatment duration are dependent on organism sensitivity testing and source of infection) (AHA [Baddour 2015])
S. aureus (prosthetic valve; methicillin-susceptible or methicillin-resistant) (off-label dose): IV, IM: 3 mg/kg/day in 2 or 3 divided doses for 2 weeks; use in combination with other antibiotics (choice of concomitant antibiotic dependent on organism sensitivity testing) (AHA [Baddour 2015])
Viridans group streptococcus (VGS) and S. bovis (native or prosthetic valve) (off-label dose): IV, IM: 3 mg/kg/day once daily (preferred) or in 3 divided doses (alternative) in combination with other antibiotics (choice of concomitant antibiotic and treatment duration are dependent on organism sensitivity testing and source of infection) (AHA [Baddour 2015])
Gonococcal infection, uncomplicated (patients with severe cephalosporin allergy) (off-label use): IM: 240 mg as a single dose in combination with oral azithromycin (CDC [Workowski 2015])
Granuloma inguinale (donovanosis) (off-label use): 1 mg/kg/dose every 8 hours; gentamicin must be used in addition to the recommended antibiotic agent and only if improvement is not evident within the first days of therapy (CDC [Workowski 2015])
Meningitis Enterococcus sp or Pseudomonas aeruginosa: IV: Loading dose 2 mg/kg, then 1.7 mg/kg/dose every 8 hours (administered with another bacteriocidal drug)
Pelvic inflammatory disease (off-label use) : Loading dose: 2 mg/kg IV or IM, then 1.5 mg/kg IV every 8 hours or 3 to 5 mg/kg IV once daily in combination with clindamycin IV. Transition from parenteral to oral therapy can usually be initiated within 24 to 48 hours of clinical improvement for a total treatment duration of 14 days (CDC [Workowski 2015])
Plague (Yersinia pestis): Treatment: 5 mg/kg/day, followed by postexposure prophylaxis with doxycycline
Pneumonia, hospital- or ventilator-associated: 7 mg/kg/day (with antipseudomonal beta-lactam or carbapenem)
Surgical (preoperative) prophylaxis (off-label use): IV: 5 mg/kg within 60 minutes prior to surgical incision with or without other antibiotics (procedure dependent). Note: Dose is based on actual body weight unless >20% above ideal body weight, then dosage requirement may best be estimated using a dosing weight of IBW + 0.4 (TBW - IBW) (Bratzler, 2013).
Synergy (for gram-positive infections): 3 mg/kg/day in 1-3 divided doses (with ampicillin)
Tularemia: 5 mg/kg/day divided every 8 hours for 1-2 weeks
Urinary tract infection: 1.5 mg/kg/dose every 8 hours
Refer to adult dosing.
Individualization is critical because of the low therapeutic index.
Use of ideal body weight (IBW) for determining the mg/kg/dose appears to be more accurate than dosing on the basis of total body weight (TBW).
Initial and periodic plasma drug levels (eg, peak and trough with conventional dosing) should be determined, particularly in critically-ill patients with serious infections or in disease states known to significantly alter aminoglycoside pharmacokinetics (eg, cystic fibrosis, burns, or major surgery).
Usual dosage ranges: IM, IV:
Infants and Children <5 years: 2.5 mg/kg/dose every 8 hours*
Children ≥5 years: 2-2.5 mg/kg/dose every 8 hours*
*Note: Higher individual doses and/or more frequent intervals (eg, every 6 hours) may be required in selected clinical situations (cystic fibrosis) or serum levels document the need.
Surgical (preoperative) prophylaxis (off-label use): Children ≥1 year: IV: 2.5 mg/kg within 60 minutes prior to surgical incision with or without other antibiotics (procedure dependent). Note: Dose is based on actual body weight unless >20% above ideal body weight, then dosage requirement may best be estimated using a dosing weight of IBW + 0.4 (TBW - IBW) (Bratzler, 2013).
Dosing: Renal Impairment
CrCl >60 mL/minute: Administer every 8 hours
CrCl 40 to 60 mL/minute: Administer every 12 hours
CrCl 20 to 39 mL/minute: Administer every 24 hours
CrCl <20 mL/minute: Loading dose, then monitor levels
High-dose therapy: Interval may be extended (eg, every 48 hours) in patients with moderate renal impairment (CrCl 30-59 mL/minute) and/or adjusted based on serum level determinations.
Intermittent hemodialysis (IHD) (administer after hemodialysis on dialysis days) (Heintz, 2009): Dialyzable (~50%; variable; dependent on filter, duration, and type of IHD):
Loading dose of 2-3 mg/kg loading dose followed by:
Mild UTI or synergy: 1 mg/kg every 48-72 hours; monitor levels
Moderate-to-severe UTI: 1-1.5 mg/kg every 48-72 hours; monitor levels
Systemic gram-negative rod infection: 1.5-2 mg/kg every 48-72 hours; monitor levels
Note: Dosing dependent on the assumption of 3 times/week, complete IHD sessions.
Peritoneal dialysis (PD):
Administration via PD fluid:
Gram-positive infection (eg, synergy): 3-4 mg/L (3-4 mcg/mL) of PD fluid
Gram-negative infection: 4-8 mg/L (4-8 mcg/mL) of PD fluid
Administration via IV, IM route during PD: Dose as for CrCl <10 mL/minute and follow levels
Continuous renal replacement therapy (CRRT) (Heintz, 2009; Trotman, 2005): Drug clearance is highly dependent on the method of renal replacement, filter type, and flow rate. Appropriate dosing requires close monitoring of pharmacologic response, signs of adverse reactions due to drug accumulation, as well as target drug concentrations (if appropriate). The following are general recommendations only (based on dialysate flow/ultrafiltration rates of 1-2 L/hour and minimal residual renal function) and should not supersede clinical judgment:
CVVH/CVVHD/CVVHDF: Loading dose of 2-3 mg/kg followed by:
Mild UTI or synergy: 1 mg/kg every 24-36 hours; monitor levels
Moderate-to-severe UTI: 1-1.5 mg/kg every 24-36 hours; monitor levels
Systemic gram-negative infection: 1.5-2.5 mg/kg every 24-48 hours; monitor levels
Dosing: Hepatic Impairment
Monitor plasma concentrations.
In moderate obesity (TBW/IBW ≥1.25) or greater (eg, morbid obesity [TBW/IBW >2]), initial dosage requirement may be estimated using a dosing weight of IBW + 0.4 (TBW - IBW) (Traynor, 1995).
IM: Administer by deep IM route if possible. Slower absorption and lower peak concentrations, probably due to poor circulation in the atrophic muscle, may occur following IM injection; in paralyzed patients, suggest IV route.
IV: Infuse over 30-120 minutes.
Some penicillins (eg, carbenicillin, ticarcillin, and 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.
Calcium, magnesium, potassium: Renal wasting may cause hypocalcemia, hypomagnesemia, and/or hypokalemia.
Stable in dextran 40, D5W, D10W, mannitol 20%, LR, NS; incompatible with fat emulsion 10%.
Y-site administration: Incompatible with allopurinol, amphotericin B cholesteryl sulfate complex, azithromycin, furosemide, hetastarch in NS, idarubicin, indomethacin, iodipamide meglumine, pemetrexed, propofol, warfarin.
Gentamicin is a colorless to slightly yellow solution which should be stored between 2°C to 30°C, but refrigeration is not recommended. IV infusion solutions mixed in NS or D5W solution are stable for 48 hours at room temperature and refrigeration (Goodwin, 1991). Premixed bag: Manufacturer expiration date; remove from overwrap stability: 30 days.
AbobotulinumtoxinA: Aminoglycosides may enhance the neuromuscular-blocking effect of AbobotulinumtoxinA. Monitor therapy
Agalsidase Alfa: Gentamicin (Systemic) may diminish the therapeutic effect of Agalsidase Alfa. Avoid combination
Agalsidase Beta: Gentamicin (Systemic) may diminish the therapeutic effect of Agalsidase Beta. Avoid combination
Amphotericin B: May enhance the nephrotoxic effect of Aminoglycosides. Monitor therapy
Arbekacin: May enhance the nephrotoxic effect of Aminoglycosides. Arbekacin may enhance the ototoxic effect of Aminoglycosides. Monitor therapy
BCG (Intravesical): Antibiotics may diminish the therapeutic effect of BCG (Intravesical). Avoid combination
BCG Vaccine (Immunization): Antibiotics may diminish the therapeutic effect of BCG Vaccine (Immunization). Monitor therapy
Bisphosphonate Derivatives: Aminoglycosides may enhance the hypocalcemic effect of Bisphosphonate Derivatives. Monitor therapy
Capreomycin: May enhance the neuromuscular-blocking effect of Aminoglycosides. Monitor therapy
CARBOplatin: Aminoglycosides may enhance the ototoxic effect of CARBOplatin. Especially with higher doses of carboplatin. Monitor therapy
Cardiac Glycosides: Aminoglycosides may decrease the serum concentration of Cardiac Glycosides. This effect has only been demonstrated with oral aminoglycoside administration. Monitor therapy
Cefazedone: May enhance the nephrotoxic effect of Aminoglycosides. Monitor therapy
Cephalosporins (2nd Generation): May enhance the nephrotoxic effect of Aminoglycosides. Monitor therapy
Cephalosporins (3rd Generation): May enhance the nephrotoxic effect of Aminoglycosides. Monitor therapy
Cephalosporins (4th Generation): May enhance the nephrotoxic effect of Aminoglycosides. Monitor therapy
Cephalothin: May enhance the nephrotoxic effect of Aminoglycosides. Monitor therapy
Cephradine: May enhance the nephrotoxic effect of Aminoglycosides. Monitor therapy
Cholera Vaccine: Antibiotics may diminish the therapeutic effect of Cholera Vaccine. Avoid combination
CISplatin: May enhance the nephrotoxic effect of Aminoglycosides. Monitor therapy
Colistimethate: Aminoglycosides may enhance the nephrotoxic effect of Colistimethate. Aminoglycosides may enhance the neuromuscular-blocking effect of Colistimethate. Consider therapy modification
CycloSPORINE (Systemic): Aminoglycosides may enhance the nephrotoxic effect of CycloSPORINE (Systemic). Monitor therapy
Distigmine: Aminoglycosides may diminish the therapeutic effect of Distigmine. Monitor therapy
Foscarnet: May enhance the nephrotoxic effect of Aminoglycosides. Avoid combination
Lactobacillus and Estriol: Antibiotics may diminish the therapeutic effect of Lactobacillus and Estriol. Monitor therapy
Loop Diuretics: May enhance the adverse/toxic effect of Aminoglycosides. Specifically, nephrotoxicity and ototoxicity. Monitor therapy
Mannitol (Systemic): May enhance the nephrotoxic effect of Aminoglycosides. Avoid combination
Mecamylamine: Aminoglycosides may enhance the neuromuscular-blocking effect of Mecamylamine. Avoid combination
Neuromuscular-Blocking Agents: Aminoglycosides may enhance the respiratory depressant effect of Neuromuscular-Blocking Agents. Monitor therapy
Nonsteroidal Anti-Inflammatory Agents: May decrease the excretion of Aminoglycosides. Data only in premature infants. Monitor therapy
OnabotulinumtoxinA: Aminoglycosides may enhance the neuromuscular-blocking effect of OnabotulinumtoxinA. Monitor therapy
Oxatomide: May enhance the ototoxic effect of Aminoglycosides. Monitor therapy
Penicillins: May decrease the serum concentration of Aminoglycosides. Primarily associated with extended spectrum penicillins, and patients with renal dysfunction. Exceptions: Amoxicillin; Ampicillin; Cloxacillin; Dicloxacillin; Nafcillin; Oxacillin; Penicillin G (Parenteral/Aqueous); Penicillin G Benzathine; Penicillin G Procaine; Penicillin V Potassium. Consider therapy modification
RimabotulinumtoxinB: Aminoglycosides may enhance the neuromuscular-blocking effect of RimabotulinumtoxinB. Monitor therapy
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. Consider therapy modification
Tenofovir Products: Aminoglycosides may increase the serum concentration of Tenofovir Products. Tenofovir Products may increase the serum concentration of Aminoglycosides. Monitor therapy
Typhoid Vaccine: Antibiotics may diminish the therapeutic effect of Typhoid Vaccine. Only the live attenuated Ty21a strain is affected. Management: Vaccination with live attenuated typhoid vaccine (Ty21a) should be avoided in patients being treated with systemic antibacterial agents. Use of this vaccine should be postponed until at least 3 days after cessation of antibacterial agents. Consider therapy modification
Vancomycin: May enhance the nephrotoxic effect of Aminoglycosides. Monitor therapy
Some penicillin derivatives may accelerate the degradation of aminoglycosides in vitro, leading to a potential underestimation of aminoglycoside serum concentration.
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, Clostridium difficile-associated diarrhea, decreased appetite, enterocolitis, nausea, sialorrhea, stomatitis, vomiting
Genitourinary: Casts in urine (hyaline, granular), changes in distal tubules (dysfunction), 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
Concerns related to adverse effects:
• Nephrotoxicity: [U.S. Boxed Warning]: May cause nephrotoxicity; usual risk factors include pre-existing 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 muscle relaxants.
• Neurotoxicity: [U.S. Boxed Warning]: May cause neurotoxicity; usual risk factors include pre-existing 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 C. difficile-associated diarrhea (CDAD) and pseudomembranous colitis; CDAD has been observed >2 months postantibiotic treatment.
• Hearing impairment: Use with caution in patients with pre-existing vertigo, tinnitus, or hearing loss.
• Hypocalcemia: Use with caution in patients with hypocalcemia.
• Neuromuscular disorders: Use with caution in patients with neuromuscular disorders, including myasthenia gravis.
• Renal impairment: Use with caution in patients with pre-existing renal insufficiency; dosage modification required.
• Long-term use: Not intended for long-term therapy due to toxic hazards associated with extended administration.
Urinalysis, urine output, BUN, serum creatinine, plasma gentamicin levels (as appropriate to dosing method). Levels are typically obtained after the third dose in conventional dosing. Hearing should be tested before, during, and after treatment; particularly in those at risk for ototoxicity or who will be receiving prolonged therapy (>2 weeks)
Some penicillin derivatives may accelerate the degradation of aminoglycosides in vitro. This may be clinically-significant for certain penicillin (ticarcillin, piperacillin, carbenicillin) and aminoglycoside (gentamicin, tobramycin) combination therapy in patients with significant renal impairment. Close monitoring of aminoglycoside levels is warranted.
Pregnancy Risk Factor
[US Boxed Warning]: Aminoglycosides may cause fetal harm if administered to a pregnant woman. Gentamicin crosses the placenta. 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 women including the treatment of acute pyelonephritis (Jolley 2010) and as an alternative antibiotic for prophylactic use prior to cesarean delivery (Bratzler 2013).
• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)
• Have patient report immediately to prescriber signs of kidney problems (urinary retention, blood in urine, change in amount of urine passed, weight gain), change in balance, severe dizziness, passing out, hearing loss, tinnitus, muscle weakness, burning or numbness feeling, twitching, seizures, shortness of breath, illogical thinking, depression, vision changes, or severe headache (HCAHPS).
• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.
Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for healthcare professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience and judgment in diagnosing, treating and advising patients.
More about gentamicin
- Gentamicin Sulfate (AHFS Monograph)
- Gentamicin Sodium Chloride (FDA)
- Gentamicin Sulfate (FDA)
- Gentamicin Sulfate Injection Concentrate (FDA)