GENTAMICIN SULFATE
Clinical safety rating: avoid
Other nephrotoxic or ototoxic drugs increase risk of toxicity Monitor peak and trough levels to minimize risk of nephrotoxicity and ototoxicity.
Aminoglycoside antibiotic that binds to the 30S ribosomal subunit, causing misreading of mRNA and inhibiting protein synthesis. Also disrupts bacterial cell membrane integrity.
| Metabolism | Minimally metabolized; primarily excreted unchanged by glomerular filtration. No significant hepatic metabolism. |
| Excretion | Renal excretion of unchanged drug accounts for >90% of elimination; biliary/fecal <2%. |
| Half-life | Terminal elimination half-life: 2-4 hours in patients with normal renal function; prolonged to 24-72 hours in renal impairment. |
| Protein binding | <30% bound to albumin; primarily free in circulation. |
| Volume of Distribution | 0.2-0.3 L/kg; approximates extracellular fluid volume; increased in edematous states. |
| Bioavailability | IM: ~100%; topical/ophthalmic: minimal systemic absorption (<0.3%); oral: negligible (<1%). |
| Onset of Action | IM: 30-60 minutes; IV: within 30 minutes; topical/ophthalmic: variable, clinical effect within 24-48 hours. |
| Duration of Action | Approximately 6-12 hours with normal renal function; prolonged in renal impairment; monitoring of trough levels recommended. |
1-2 mg/kg IV every 8 hours or 3-5 mg/kg IV every 24 hours for extended-interval dosing; typical duration 7-10 days.
| Dosage form | INJECTABLE |
| Renal impairment | GFR 20-50 mL/min: 1-2 mg/kg IV every 12 hours; GFR 10-19 mL/min: 1-2 mg/kg IV every 24 hours; GFR <10 mL/min: 1-2 mg/kg IV every 48-72 hours; monitor serum levels. |
| Liver impairment | No dose adjustment required for Child-Pugh Class A, B, or C; monitor renal function. |
| Pediatric use | Neonates: 2.5-5 mg/kg IV every 12-24 hours based on gestational age and postnatal age; Children: 2-2.5 mg/kg IV every 8 hours; extended-interval dosing: 4-7 mg/kg IV every 24 hours. |
| Geriatric use | Reduced initial dose (1-2 mg/kg IV) based on renal function; monitor serum creatinine and drug trough levels; increased risk of nephrotoxicity and ototoxicity. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Other nephrotoxic or ototoxic drugs increase risk of toxicity Monitor peak and trough levels to minimize risk of nephrotoxicity and ototoxicity.
| FDA category | Positive |
| Breastfeeding | Gentamicin is excreted into breast milk in low concentrations (M/P ratio approximately 0.2-0.5). Oral bioavailability is poor in infants, but potential for disruption of infant gut flora and rare allergic reactions. Use with caution, monitoring infant for diarrhea, rash, or hearing issues. |
| Teratogenic Risk |
■ FDA Black Box Warning
Potential for nephrotoxicity (especially in patients with pre-existing renal impairment or those receiving other nephrotoxic drugs) and ototoxicity (vestibular and cochlear, which may be irreversible). Risk is increased with higher doses, prolonged therapy, or in elderly patients. Also, neuromuscular blockade and respiratory paralysis have been reported, particularly with concurrent use of anesthetics or neuromuscular blocking agents. Use during pregnancy may cause fetal harm.
| Common Effects | Nephrotoxicity |
| Serious Effects |
["Hypersensitivity to gentamicin or any aminoglycoside","Previous serious toxic reaction to aminoglycosides (e.g., ototoxicity, nephrotoxicity)"]
| Precautions | ["Monitor renal function (serum creatinine, BUN, urine output) and drug levels (peak and trough) to avoid toxicity.","Assess hearing (audiometry) before and during therapy; discontinue if tinnitus or vertigo occurs.","Use with caution in elderly, dehydrated, or patients with renal impairment.","Avoid concurrent use of other nephrotoxic or ototoxic drugs (e.g., loop diuretics, vancomycin, cisplatin).","May exacerbate muscle weakness in patients with myasthenia gravis or other neuromuscular disorders.","Prolonged use may result in overgrowth of non-susceptible organisms."] |
Loading safety data…
| Aminoglycosides cross the placenta. First trimester: No clear evidence of major malformations, but risk cannot be excluded. Second/third trimester: Potential for fetal ototoxicity (8th cranial nerve damage) and nephrotoxicity, especially with prolonged or high-dose exposure; use only if clearly needed. |
| Fetal Monitoring | Monitor maternal renal function (serum creatinine, BUN), gentamicin trough and peak levels, and auditory function. Fetal monitoring includes ultrasound for growth and amniotic fluid volume; consider newborn hearing screen after delivery if exposure occurred in 2nd/3rd trimester. |
| Fertility Effects | No direct evidence of adverse effects on fertility in humans. Animal studies show no significant reproductive toxicity at therapeutic doses. However, systemic illness requiring gentamicin may indirectly affect fertility. |