Drug class: Aminoglycosides
CAS number: 1405-41-0

Medically reviewed by Drugs.com on Jun 29, 2023. Written by ASHP.

Introduction

Antibacterial; aminoglycoside antibiotic obtained from cultures of Micromonospora purpurea.^{a b c h}

Uses for Gentamicin

Bone and Joint Infections

Treatment of serious bone and joint infections caused by susceptible Staphylococcus aureus, Citrobacter, Enterobacter, Escherichia coli, Klebsiella, Proteus, Serratia, or Pseudomonas aeruginosa.^{a b c} Used as an adjunct to other appropriate anti-infectives.^e

Endocarditis

Treatment of staphylococcal endocarditis^{† [off-label]}; used as an adjunct to recommended anti-infectives (e.g., nafcillin, oxacillin, cefazolin, vancomycin).^{k l}

Treatment of endocarditis^{† [off-label]} caused by viridans streptococci (e.g., S. milleri, S. mitis, S. mutans) or S. bovis (nonenterococcal group D streptococcus); used as an adjunct to recommended anti-infectives (e.g., penicillin G, ceftriaxone, vancomycin).^{k l}

Treatment of enterococcal endocarditis^{† [off-label]};^{k l} used in conjunction with an appropriate anti-infective (e.g., penicillin G, ampicillin, vancomycin).^{k l}

Treatment of endocarditis caused by slow-growing fastidious gram-negative bacilli termed the HACEK group^{† [off-label]} (i.e., Haemophilus parainfluenzae, H. aphrophilus, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, Kingella kingae); used in conjunction with ampicillin.^l

Prevention of bacterial endocarditis in patients undergoing certain GU and GI (except esophageal) procedures^{† [off-label]} who have cardiac conditions that put them at high risk.²⁵⁵ Gentamicin used as an adjunct to ampicillin or vancomycin (used in penicillin-allergic patients) in high-risk patients; amoxicillin, ampicillin, or vancomycin is used alone in those at moderate risk.²⁵⁵ Consult most recent AHA recommendations for specific information on which cardiac conditions are associated with high or moderate risk of endocarditis and which procedures require prophylaxis.²⁵⁵

Gynecologic Infections

Treatment of pelvic inflammatory disease^† (PID); used in conjunction with clindamycin.^{201 212} When a parenteral regimen is indicated for treatment of PID, IV clindamycin in conjunction with an IV or IM aminoglycoside (e.g., gentamicin) is one possible regimen since it provides good coverage for anaerobes.^{201 212} However, this regimen may not provide optimal coverage for Neisseria gonorrhoeae and Chlamydia trachomatis, and a regimen of cefoxitin (or cefotetan) and doxycycline may be preferred when these organisms are suspected as primary pathogens.²⁰¹

Intra-abdominal Infections

Treatment of serious intra-abdominal infections (including peritonitis) caused by susceptible S. aureus, Citrobacter, Enterobacter, E. coli, Klebsiella, Proteus, Serratia, or Ps. aeruginosa.^{a b c} Used as an adjunct to other appropriate anti-infectives.^e

Meningitis and Other CNS Infections

Treatment of CNS infections (meningitis) caused by susceptible S. aureus, Citrobacter, Enterobacter, E. coli, Klebsiella, Proteus, Serratia, or Ps. aeruginosa.^{a b c e}

Aminoglycosides should not be used alone for treatment of meningitis;ⁱ usually used as an adjunct to other anti-infectives in initial treatment.^{f i} Used in conjunction with ampicillin for initial empiric treatment of neonatal S. agalactiae meningitis or for Listeria monocytogenes meningitis.^f

Respiratory Tract Infections

Treatment of serious respiratory tract infections caused by susceptible S. aureus, Citrobacter, Enterobacter, E. coli, Klebsiella, Proteus, Serratia, or Ps. aeruginosa.^{a b c d e} Used as an adjunct to an appropriate β-lactam (e.g., ceftriaxone, cefotaxime, cefepime, piperacillin and tazobactam, ticarcillin and clavulanate) or carbapenem (e.g., imipenem, meropenem) for empiric treatment of nosocomial pneumonia.^e

Septicemia

Treatment of septicemia caused by susceptible S. aureus, Citrobacter, Enterobacter, E. coli, Klebsiella, Proteus, Serratia, or Ps. aeruginosa.^{a b c d e}

Used as an adjunct to an appropriate β-lactam (e.g., ceftriaxone, cefotaxime, cefepime, piperacillin and tazobactam, ticarcillin and clavulanate) or carbapenem (e.g., imipenem, meropenem) for empiric treatment of life-threatening septicemia.^e

Skin and Skin Structure Infections

Treatment of serious skin and skin structure infections caused by susceptible S. aureus, Citrobacter, Enterobacter, E. coli, Klebsiella, Proteus, Serratia, or Ps. aeruginosa.^{a b c} Used as an adjunct to other appropriate anti-infectives.^e

Urinary Tract Infections (UTIs)

Treatment of serious complicated and recurrent UTIs caused by susceptible S. aureus, Citrobacter, Enterobacter, E. coli, Klebsiella, Proteus, Serratia, or Ps. aeruginosa.^{a b c d e} Used as an adjunct to other appropriate anti-infectives.^e

Not indicated for uncomplicated UTIs unless causative organism is resistant to other less-toxic alternatives.^{a b c}

Brucellosis

Treatment of brucellosis^†; used in conjunction with a tetracycline or co-trimoxazole.^e

Granuloma Inguinale (Donovanosis)

Adjunct for treatment of granuloma inguinale^† (donovanosis) caused by Calymmatobacterium granulomatis.²⁰¹ CDC recommends doxycycline or co-trimoxazole as drugs of choice; ciprofloxacin, erythromycin, and azithromycin are alternatives.²⁰¹ Some clinicians suggest adding an IV aminoglycoside (e.g., gentamicin) if improvement is not evident within the first few days of therapy and in pregnant or HIV-infected patients.²⁰¹

Plague

Treatment of plague^† caused by Yersinia pestis, including naturally occurring or endemic bubonic, septicemic, or pneumonic plague or plague that occurs as the result of biologic warfare or bioterrorism.^{256 258 e f} Although streptomycin generally has been considered the drug of choice for plague, gentamicin also is a drug of choice since it may be as effective and is more readily available than streptomycin.^f

Tularemia

Treatment of tularemia^† caused by Francisella tularensis, including naturally occurring or endemic tularemia or tularemia that occurs as the result of biologic warfare or bioterrorism.^{257 258} Although streptomycin generally has been considered the drug of choice for tularemia, gentamicin is more readily available and may be used as an alternative when streptomycin is unavailable.^{257 258}

Empiric Therapy in Febrile Neutropenic Patients

Empiric anti-infective therapy of presumed bacterial infections in febrile neutropenic patients^†.^{d e i j} Used in conjunction with an appropriate antipseudomonal cephalosporin (e.g., ceftazidime, ceftriaxone), extended-spectrum penicillin (e.g., ticarcillin, piperacillin and tazobactam, ticarcillin and clavulanate), or carbapenem (e.g., imipenem, meropenem).^{e j}

Consult published protocols for the treatment of infections in febrile neutropenic patients for specific recommendations regarding selection of the initial empiric regimen, when to change the initial regimen, possible subsequent regimens, and duration of therapy in these patients.^j Consultation with an infectious disease expert knowledgeable about infections in immunocompromised patients also is advised.^j

Gentamicin Dosage and Administration

Administration

Administer by IV infusion or IM injection.^{a b c} Also has been administered without preservatives intrathecally or intraventricularly to supplement IM or IV administration in the treatment of CNS infections.^h

IV Infusion

For solution and drug compatibility information, see Compatibility under Stability.

Reconstitution and Dilution

For adults, prepare IV infusions by diluting the calculated dose of gentamicin with 50–200 mL of 0.9% sodium chloride or 5% dextrose injection.^h

ADD-Vantage vials should be diluted according to the manufacturer’s directions prior to IV infusion.^h

Rate of Administration

IV infusions are given over 30 minutes to 2 hours.^h

IM Injection

For IM injection, the appropriate dose should be withdrawn from multiple-dose vials.^h

Solutions prepared from or commercially available in pharmacy bulk packages, those available in ADD-Vantage vials, or the commercially available injections in 0.9% sodium chloride should not be used for IM administration of the drug.^h

Dosage

Available as gentamicin sulfate; dosage is expressed in terms of gentamicin.^{a b c}

Dosage is identical for either IV or IM administration.^{a b c}

Dosage should be based on patient’s pretreatment body weight.^{a b c}

Many clinicians recommend that dosage be determined using appropriate pharmacokinetic methods for calculating dosage requirements and patient-specific pharmacokinetic parameters (e.g., elimination rate constant, volume of distribution) derived from serum concentration-time data; in determining dosage, the susceptibility of the causative organism, the severity of infection, and the patient’s immune and clinical status also must be considered.^{214 215 216 217 218 242 243 244 245 246 247 248 249}

Peak and trough serum gentamicin concentrations should be determined periodically and dosage adjusted to maintain desired serum concentrations whenever possible, especially in patients with life-threatening infections, suspected toxicity or nonresponse to treatment, decreased or varying renal function, and/or when increased aminoglycoside clearance (e.g., patients with cystic fibrosis, burns) or prolonged therapy is likely.^{235 236 237 238 239 240 241 242 250}

In general, desirable peak serum concentrations of gentamicin are 4–12 mcg/mL and trough concentrations of the drug should not exceed 1–2 mcg/mL.^h Some evidence suggests that an increased risk of toxicity may be associated with prolonged peak serum gentamicin concentrations >10–12 mcg/mL and/or trough concentrations >2 mcg/mL.^h

Once-daily administration^† of aminoglycosides is at least as effective as, and may be less toxic than, conventional dosage regimens employing multiple daily doses.^{218 219 220 221 222 223 224 225 226 227 228 229 230 231 251 252 253 254}

Pediatric Patients

General Dosage for Neonates

IV or IM

Manufacturer recommends 2.5 mg/kg every 12 hours in premature or full-term neonates ≤1 week of age and 2.5 mg/kg every 8 hours for older neonates.^{a b c}

Neonates <1 week of age: AAP recommends 2.5 mg/kg every 18–24 hours for those weighing <1.2 kg and 2.5 mg/kg every 12 hours for those weighing ≥1.2 kg.^f

Neonates 1–4 weeks of age: AAP recommends 2.5 mg/kg every 18–24 hours for those weighing <1.2 kg, 2.5 mg/kg every 8 or 12 hours for those weighing 1.2–2 kg, and 2.5 mg/kg every 8 hours for those weighing >2 kg.^f

General Dosage for Infants and Children

IV or IM

Older infants and children: manufacturer recommends 2.5 mg/kg every 8 hours for older neonates.^{a b c}

Children ≥1 month of age: AAP recommends 3–7.5 mg/kg given in 3 divided doses for treatment of severe infections.^f Inappropriate for mild to moderate infections according to AAP.^f

Endocarditis†

Treatment of Staphylococcal Endocarditis†

IV or IM

3 mg/kg daily in 3 divided doses; dosage adjusted to achieve peak serum gentamicin concentrations approximately 3 mcg/mL and trough concentrations <1 mcg/mL.^k

Used in conjunction with nafcillin, oxacillin, cefazolin, or vancomycin; gentamicin used only during the first 3–5 days for native valve infections or during the first 2 weeks for prosthetic valve infections.^k

Treatment of Endocarditis Caused by Viridans Streptococci or S. bovis†

IV or IM

3 mg/kg daily in 3 divided doses; dosage adjusted to achieve peak serum gentamicin concentrations approximately 3 mcg/mL and trough concentrations <1 mcg/mL.^k

Used in conjunction with penicillin G or ceftriaxone; usual duration is 2 weeks for penicillin-susceptible strains (MIC ≤0.1 mcg/mL), 2 weeks for relatively resistant strains (MIC >0.1–0.5 mcg/mL), or 4–6 weeks for strains with high level penicillin resistance (MIC >0.5 mcg/mL).^k If used with vancomycin in patients unable to receive a β-lactam, a 6-week regimen is recommended.^k

Treatment of Enterococcal Endocarditis†

IV or IM

3 mg/kg daily in 3 divided doses; dosage adjusted to achieve peak serum gentamicin concentrations approximately 3 mcg/mL and trough concentrations <1 mcg/mL.^k

Used in conjunction with penicillin G or ceftriaxone; usual duration is 2 weeks for penicillin-susceptible strains (MIC ≤0.1 mcg/mL), 2 weeks for relatively resistant strains (MIC >0.1–0.5 mcg/mL), or 4–6 weeks for strains with high level penicillin resistance (MIC >0.5 mcg/mL).^k If used with vancomycin in patients unable to receive a β-lactam, a 6-week regimen is recommended.^k

Prevention of Endocarditis in Patients Undergoing Certain Genitourinary or GI (except Esophageal) Procedures†

IV or IM

For high-risk patients: 1.5 mg/kg (up to 120 mg) given within 30 minutes prior to the procedure; used in conjunction with recommended regimens of ampicillin or vancomycin.²⁵⁵

Plague†

Treatment of Plague†

IV or IM

Premature neonates and neonates ≤1 week of age: 2.5 mg/kg twice daily.²⁵⁶

Infants and older children: 2.5 mg/kg 3 times daily.²⁵⁶

Usual duration is 10 days;²⁵⁶ some experts recommend 10–14 days.²⁵⁸

Tularemia†

Treatment of Tularemia†

IV or IM

2.5 mg/kg 3 times daily for 10 days.²⁵⁷

Adults

General Adult Dosage

Treatment of Serious Infections

IV or IM

3 mg/kg daily given in 3 equally divided doses every 8 hours.^{a b c}

Treatment of Life-threatening Infections

IV or IM

≤5 mg/kg daily given in 3 or 4 equally divided doses.^{a b c} Dosage should be reduced to 3 mg/kg daily when clinically indicated.^{a b c}

Endocarditis†

Treatment of Staphylococcal Endocarditis†

IV or IM

1 mg/kg every 8 hours.^l Used in conjunction with nafcillin, oxacillin, cefazolin, or vancomycin; gentamicin used only during the first 3–5 days of therapy for native valve infections or during the first 2 weeks for prosthetic valve infections.^l

Treatment of Endocarditis Caused by Viridans Streptococci or S. bovis†

IV or IM

1 mg/kg every 8 hours.^l Used in conjunction with penicillin G, ceftriaxone, or vancomycin; gentamicin used only during the first 2 weeks of therapy.^l

Treatment of Enterococcal Endocarditis†

IV or IM

1 mg/kg every 8 hours.^l Used in conjunction with penicillin G, ampicillin, or vancomycin; usual duration is 4–6 weeks.^l

Treatment of Endocarditis Caused by HACEK group†

IV

1 mg/kg every 8 hours.^l Used in conjunction with ampicillin; usual duration is 4 weeks.^l (HACEK: H. parainfluenzae, H. aphrophilus, A. actinomycetemcomitans, C. hominis, E. corrodens, K. kingae)

Prevention of Endocarditis in Patients Undergoing Certain Genitourinary or GI (except Esophageal) Procedures†

IV or IM

For high-risk patients: 1.5 mg/kg (up to 120 mg) given within 30 minutes prior to the procedure; used in conjunction with recommended regimens of ampicillin or vancomycin.²⁵⁵

Gynecologic Infections†

Pelvic Inflammatory Disease† (PID)

IV or IM

Initially, 2 mg/kg followed by 1.5 mg/kg every 8 hours;^{201 212} used in conjunction with IV clindamycin (900 mg every 8 hours).^{201 212} After clinical improvement occurs, discontinue IV clindamycin and gentamicin and switch to oral clindamycin (450 mg 4 times daily) or oral doxycycline (100 mg twice daily) to complete 14 days of therapy.²⁰¹

Granuloma Inguinale (Donovanosis)†

IV

1 mg/kg every 8 hours; added as an adjunct to the recommended or alternative drugs (doxycycline, co-trimoxazole, ciprofloxacin, erythromycin, azithromycin) if improvement is not evident within the first few days of therapy or in pregnant or HIV-infected patients.²⁰¹

Plague†

Treatment of Plague†

IV or IM

5 mg/kg once daily or, alternatively, a 2-mg/kg loading dose following by 1.7 mg/kg 3 times daily.^{256 258} Usual duration is 10 days;²⁵⁶ some experts recommend 10–14 days.²⁵⁸

Tularemia†

Treatment of Tularemia†

IV or IM

5 mg/kg once daily for 10 days;²⁵⁷ some experts recommend 3–5 mg/kg daily for 10–14 days.²⁵⁸

Special Populations

Renal Impairment

Dosage adjustments necessary in patients with renal impairment.^{a b c} Whenever possible monitor serum gentamicin concentrations, especially in patients with changing renal function.^{a b c}

Various methods have been used to determine aminoglycoside dosage for patients with renal impairment and there is wide variation in dosage recommendations for these patients.^h The manufacturers recommend an initial dose of 1–1.7 mg/kg, followed by 1-mg/kg doses given at intervals (in hours) calculated by multiplying the patient’s steady-state serum creatinine (in mg/dL) by 8.^h The dosing method of Sarubbi and Hull, which is based on corrected Cl_cr also has been recommended.^h Specialized references should be consulted for specific information on dosage for patients with renal impairment.

Dosage calculation methods should not be used in patients undergoing hemodialysis or peritoneal dialysis.^h In patients with renal failure undergoing hemodialysis, the manufacturers recommend supplemental doses of 1–1.7 mg/kg at the end of each dialysis period in adults and supplemental doses of 2–2.5 mg/kg at the end of each dialysis period in children.^h

Geriatric Patients

Select dosage with caution and closely monitor renal function because of age-related decreases in renal function.^{a b c}

No dosage adjustments except those related to renal impairment.^{a b c} (See Renal Impairment under Dosage and Administration.)

Cautions for Gentamicin

Contraindications

• History of hypersensitivity or serious toxic reactions to gentamicin or other aminoglycosides.^{a b c}

Warnings/Precautions

Warnings

Ototoxicity

Patients receiving aminoglycosides should be under close clinical observation because of possible ototoxicity.^{a b c}

Vestibular and permanent bilateral auditory ototoxicity occurs most frequently in those with past or present history of renal impairment, those receiving other ototoxic drugs, and those who receive high dosage or prolonged treatment.^{a b c}

Serial audiograms should be obtained, if feasible, in patients old enough to be tested, particularly in high-risk patients.^{a b c}

Discontinue gentamicin or adjust dosage if there is evidence of ototoxicity (dizziness, vertigo, tinnitus, roaring in the ears, hearing loss).^{a b c}

Some aminoglycosides have caused fetal ototoxicity when administered to pregnant women.^{a b c} (See Pregnancy under Cautions.)

Nephrotoxicity

Patients receiving aminoglycosides should be under close clinical observation because of possible nephrotoxicity.^{a b c} Renal function should be assessed prior to and periodically during therapy.^{a b c}

Nephrotoxicity occurs most frequently in those with past or present history of renal impairment, those receiving other nephrotoxic drugs, and those who receive high dosage or prolonged treatment.^{a b c}

Dosage reduction may be desirable if other evidence of renal dysfunction occurs (e.g., decreased Cl_cr, decreased urine specific gravity, increased BUN or S_cr, oliguria).^{a b c}

If azotemia increases or if a progressive decrease in urinary output occurs, discontinue gentamicin.^{a b c}

Neuromuscular Blockade

Neuromuscular blockade and respiratory paralysis reported with high gentamicin dosage (40 mg/kg) in animal studies.^{a b c}

Possibility of neuromuscular blockade should be considered, especially in patients receiving anesthetics or neuromuscular blocking agents (e.g., tubocurarine, succinylcholine, decamethonium) or in those receiving massive transfusions of citrate-anticoagulated blood.^{a b c}

Calcium salts may reverse neuromuscular blockade.^{a b c}

Sensitivity Reactions

Cross-Hypersensitivity

Cross-allergenicity occurs among the aminoglycosides.^{a b c}

Sulfite Sensitivity

Gentamicin injection contains sodium metabisulfite, which may cause allergic-type reactions (including anaphylaxis and life-threatening or less severe asthmatic episodes) in certain susceptible individuals.^{a b c}

General Precautions

Selection and Use of Anti-infectives

To reduce development of drug-resistant bacteria and maintain effectiveness of gentamicin and other antibacterials, use only for treatment or prevention of infections proven or strongly suspected to be caused by susceptible bacteria.^c

When selecting or modifying anti-infective therapy, use results of culture and in vitro susceptibility testing.^c In the absence of such data, consider local epidemiology and susceptibility patterns when selecting anti-infectives for empiric therapy.^c

Usually used in conjunction with other anti-infectives (e.g., penicillins, cephalosporins) for empiric treatment of serious infections pending results of in vitro susceptibility tests.^{a b c} If anaerobic bacteria are suspected, concomitant use of an anti-infective active against anaerobes is necessary.^{a b c}

Superinfection

Possible emergence and overgrowth of nonsusceptible bacteria or fungi.^{a b c} Discontinue drug and institute appropriate therapy if superinfection occurs.^{a b c}

Interactions

Because of possible additive toxicity, avoid concurrent and/or sequential use of other neurotoxic or nephrotoxic drugs (systemic, oral, or topical), particularly bacitracin, cisplatin, amphotericin B, cephaloridine (no longer available in US), paromomycin, viomycin, polymyxin B, colistin, vancomycin, or other aminoglycosides.^{a b c} Do not administer concurrently with potent diuretics.^{b c} (See Specific Drugs under Interactions.)

Consider possibility of neuromuscular blockade and respiratory paralysis in patients receiving anesthetics or neuromuscular blocking agents (e.g., tubocurarine, succinylcholine, decamethonium).^{a b c} (See Specific Drugs under Interactions.)

Use with caution in patients with muscular disorders such as myasthenia gravis or parkinsonism since drugs used in these patients may aggravate muscle weakness because of their potential curare-like effect on the neuromuscular junction.^{a b c}

Topical Instillation

Aminoglycoside may be absorbed in significant quantities from body surfaces after topical instillation^† and may cause neurotoxicity and nephrotoxicity.^{a b c}

Specific Populations

Pregnancy

Category D.^{a c}

Possibility of fetal harm if administered to a pregnant woman.^{a b c} Complete, irreversible, bilateral congenital deafness reported when another aminoglycoside (i.e., streptomycin) was used during pregnancy.^{a b c}

If used during pregnancy or if patient becomes pregnant while receiving gentamicin, the patient should be apprised of the potential hazard to the fetus.^{a b c}

Lactation

Low concentrations of aminoglycosides may be distributed into milk.ⁱ Use with caution.ⁱ

Pediatric Use

Use with caution in neonates and premature infants because renal immaturity in these patients may result in prolonged serum half-life.ⁱ

Geriatric Use

Select dosage with caution and closely monitor renal function because of age-related decreases in renal function.^{a b c d}

Monitoring renal function during aminoglycoside therapy is particularly important in geriatric patients.^{a b c d} Cl_cr may be more useful than determining BUN or S_cr.^{a b c d}

Renal Impairment

Risk of neurotoxicity (manifested as vestibular and permanent bilateral auditory ototoxicity) is greater in patients with renal damage than in other patients.^{a b c}

Renal function should be assessed prior to and during therapy.^{a b c}

Eighth-cranial nerve function should be monitored closely, especially in patients who have known or suspected renal impairment at the start of treatment and also in those whose renal function is initially normal but who develop signs of renal dysfunction during treatment.^{a b c}

Common Adverse Effects

Ototoxicity or nephrotoxicity.^{a b c i}

Drug Interactions

Neurotoxic, Ototoxic, or Nephrotoxic Drugs

Concomitant or sequential use with other drugs that have neurotoxic, ototoxic, or nephrotoxic effects (e.g., aminoglycosides, acyclovir, amphotericin B, bacitracin, capreomycin, cephalosporins, colistin, cephaloridine, viomycin, polymyxin B, colistin, cisplatin, vancomycin) may result in additive toxicity and should be avoided, if possible.^{a b c i} In addition, because of the possibility of an increased risk of ototoxicity due to additive effects or altered serum and tissue aminoglycoside concentrations, aminoglycosides should not be given concurrently with potent diuretics such as ethacrynic acid or furosemide.^{b c i}

Specific Drugs

Gentamicin Pharmacokinetics

Absorption

Bioavailability

Not absorbed orally; must be given parenterally.^{d i}

Rapidly absorbed following IM injection; peak plasma concentrations attained within 30–90 minutes.^{a b c i}

Distribution

Extent

Distributed into bone, heart, gallbladder, lung tissue, bile, sputum, bronchial secretions, and interstitial, pleural, and synovial fluids.^{a b c d h}

Only low concentrations distributed into CSF following IM or IV administration.ⁱ

Crosses the placenta.^d Aminoglycosides may be distributed into milk in low concentrations.ⁱ

Plasma Protein Binding

Only minimally bound to plasma proteins.^{a b c}

Elimination

Metabolism

Not metabolized.ⁱ

Elimination Route

50–93% of a single IM dose excreted unchanged by glomerular filtration within 24 hours.^h

May be removed by hemodialysis^{a b c i} or peritoneal dialysis.ⁱ

Half-life

2–3 hours in adults with normal renal function.^h

3–3.5 hours in infants 1 week to 6 months of age and 5.5 hours in full-term infants and large premature infants <1 week of age.^h In small premature infants, plasma half-life is approximately 5 hours in those weighing >2 kg, 8 hours in those weighing 1.5–2 kg, and 11.5 hours in those weighing <1.5 kg.^h

Special Populations

Half-life is 24–60 hours in adults with severe renal impairment.^h

Stability

Storage

Parenteral

Injection for IV Infusion or IM Injection

15–30°C.^{a c}

Compatibility

Parenteral

Solution CompatibilityHID

Drug Compatibility

Actions and Spectrum

• Usually bactericidal.^{a b c i}

• Inhibits protein synthesis in susceptible bacteria by irreversibly binding to 30S ribosomal subunits.^{a b c i}

• In vitro spectrum of activity includes many gram-negative aerobic bacteria (including most Enterobacteriaceae and Pseudomonas aeruginosa) and some aerobic gram-positive bacteria.^{a b c d i h} Inactive against fungi, viruses, and most anaerobic bacteria.^{d i h}

• Gram-positive aerobes: active in vitro against penicillinase-producing and nonpenicillinase-producing Staphylococcus aureus and S. epidermidis.^{a b c d i} May be active against some strains of oxacillin-resistant (methicillin-resistant) staphylococci.^{a b c d} Streptococcus pyogenes (group A β-hemolytic streptococci), S. pneumoniae, and group D streptococci.^{a b c d}

• Gram-negative aerobes: active in vitro and in clinical infections against Acinetobacter, Citrobacter, Enterobacter, Escherichia coli, Haemophilus influenzae, Klebsiella, Morganella, Proteus, Providencia, Pseudomonas, Salmonella, Shigella, and Serratia.^{a b c d i} Burkholderia and Stenotrophomonas usually are resistant.^d

• Partial cross-resistance occurs between gentamicin and other aminoglycosides.ⁱ

Advice to Patients

• Advise patients that antibacterials (including gentamicin) should only be used to treat bacterial infections and not used to treat viral infections (e.g., the common cold).^c

• Importance of completing full course of therapy, even if feeling better after a few days.^c

• Advise patients that skipping doses or not completing the full course of therapy may decrease effectiveness and increase the likelihood that bacteria will develop resistance and will not be treatable with gentamicin or other antibacterials in the future.^c

• Importance of informing clinician if there is evidence of ototoxicity (dizziness, vertigo, tinnitus, roaring in the ears, hearing loss), other neurotoxicity (numbness, skin tingling, muscle twitching, seizures), or nephrotoxicity (e.g., decreased urine output).^{a b c}

• Importance of informing clinician of existing or contemplated therapy, including prescription and OTC drugs.^{a b c}

• Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.^{a b c}

• Importance of advising patients of other important precautionary information.^{a b c} (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

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