GENTACIDIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for GENTACIDIN (GENTACIDIN).
Aminoglycoside antibiotic that binds to the 30S ribosomal subunit, causing misreading of mRNA and inhibiting protein synthesis.
| Metabolism | Primarily excreted unchanged by glomerular filtration; minimal hepatic metabolism. |
| Excretion | Renal: 95-98% unchanged via glomerular filtration; biliary/fecal: <2%. |
| Half-life | 2-3 hours in adults with normal renal function; extended to 24-48 hours in anuria or severe renal impairment, requiring dose adjustment. |
| Protein binding | 10-20% bound to albumin. |
| Volume of Distribution | 0.2-0.4 L/kg, indicating distribution primarily in extracellular fluid. |
| Bioavailability | IM: 90-100%; topical: negligible systemic absorption (<10%); oral: <1%. |
| Onset of Action | IV: 15-30 min after infusion; IM: 1-2 hours; topical: variable, within 4-6 hours. |
| Duration of Action | 6-8 hours with normal renal function; prolonged in renal impairment; drug concentration-dependent. |
5-7 mg/kg IV every 24 hours.
| Dosage form | OINTMENT |
| Renal impairment | GFR >60 mL/min: 5-7 mg/kg q24h; GFR 30-59: 3-4 mg/kg q24-48h; GFR 15-29: 2-3 mg/kg q48-72h; GFR <15: 1-2 mg/kg q72-96h or after dialysis. |
| Liver impairment | No adjustment required for Child-Pugh A, B, or C; monitor levels if severe hepatic impairment. |
| Pediatric use | Neonates: 4-5 mg/kg IV q24h; Infants/Children: 5-7.5 mg/kg IV q24h; adjust per therapeutic drug monitoring. |
| Geriatric use | Initiate at lower end (5 mg/kg IV q24h) and adjust based on renal function; monitor serum creatinine and drug levels closely. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for GENTACIDIN (GENTACIDIN).
| Breastfeeding | Gentamicin is excreted into human milk in low concentrations. The milk-to-plasma (M/P) ratio is approximately 0.2-0.4. Oral bioavailability in infants is poor, so systemic effects are unlikely. However, due to potential for alteration of infant gut flora and direct effects (e.g., diarrhea, allergic reactions), caution is advised. The American Academy of Pediatrics considers gentamicin compatible with breastfeeding. Use only if clearly needed, and monitor infant for signs of gastrointestinal disturbance. |
| Teratogenic Risk | Gentamicin is an aminoglycoside antibiotic. Animal studies have shown evidence of fetal harm (nephrotoxicity, ototoxicity). There are no adequate well-controlled studies in pregnant women. Gentamicin crosses the placenta. Risk cannot be ruled out. The drug should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. First trimester: Theoretical risk of ototoxicity and nephrotoxicity. Second and third trimesters: Potential for fetal ototoxicity (eighth cranial nerve) and nephrotoxicity, especially with prolonged or high-dose therapy. |
■ FDA Black Box Warning
WARNING: Nephrotoxicity and ototoxicity, even at therapeutic doses; monitor renal function and hearing. Neurotoxicity may occur. Avoid concurrent use with other nephrotoxic or ototoxic drugs.
| Serious Effects |
Hypersensitivity to gentamicin or any aminoglycoside; myasthenia gravis; history of ototoxicity or nephrotoxicity with prior aminoglycoside use.
| Precautions | Monitor renal function, serum drug levels, and audiometric tests. Use caution in elderly, dehydrated, or renally impaired patients. Prolonged use may lead to superinfection. |
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| Fetal Monitoring | Maternal: Renal function (serum creatinine, BUN, urine output), serum drug concentrations (peak and trough), audiometric testing if prolonged therapy (baseline and periodic). Fetal/neonatal: No specific monitoring required unless signs of toxicity; consider auditory and renal assessment if high cumulative dose or prolonged exposure. |
| Fertility Effects | No well-controlled studies in humans. Animal studies have not reported adverse effects on fertility. However, generalized toxicity (e.g., renal impairment) could indirectly affect reproductive function. Use only when clearly indicated. |