BRISTAGEN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for BRISTAGEN (BRISTAGEN).
Bristagen (amikacin) is an aminoglycoside antibiotic that irreversibly binds to the 30S ribosomal subunit, inhibiting bacterial protein synthesis.
| Metabolism | Amikacin undergoes minimal metabolism (<10%) and is primarily excreted unchanged by glomerular filtration. |
| Excretion | Renal (90% unchanged via glomerular filtration); biliary/fecal excretion <10%. |
| Half-life | 2.5 hours (prolonged to 20-40 hours in renal impairment). |
| Protein binding | 0-30% (low binding to albumin). |
| Volume of Distribution | 0.25 L/kg (confined mainly to extracellular fluid; critically ill or edematous patients may have higher Vd). |
| Bioavailability | IM: ~100%. |
| Onset of Action | IM: 30-60 minutes; IV: immediate. |
| Duration of Action | 6-8 hours (dose- and infection-site dependent; adjust interval in renal dysfunction). |
1-2 mg/kg IM or IV every 8-12 hours; typical adult dose is 1 mg/kg every 8 hours.
| Dosage form | INJECTABLE |
| Renal impairment | CrCl 20-50 mL/min: 1-2 mg/kg every 24-36 hours; CrCl <20 mL/min: 1-2 mg/kg every 48-72 hours; hemodialysis: 1-2 mg/kg after dialysis. |
| Liver impairment | No dose adjustment required for hepatic impairment; monitor drug levels if severe. |
| Pediatric use | 2.5 mg/kg/dose IM or IV every 8-12 hours for neonates; 2-2.5 mg/kg/dose every 8 hours for infants and children. |
| Geriatric use | Start at lower end of dosing range (0.5-1 mg/kg) and adjust based on renal function; avoid if CrCl <30 mL/min unless necessary. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for BRISTAGEN (BRISTAGEN).
| Breastfeeding | M/P ratio unknown; small amounts excreted into breast milk. Due to risk of infant gut flora alteration and potential for ototoxicity/nephrotoxicity, caution advised. American Academy of Pediatrics considers compatible with breastfeeding, but monitor infant for diarrhea, rash, or signs of toxicity. |
| Teratogenic Risk | First trimester: Risk of fetal ototoxicity and nephrotoxicity; aminoglycosides cross the placenta. Second trimester: Continued risk; avoid due to potential for irreversible fetal harm. Third trimester: Use only for life-threatening infections; theoretical risk of neonatal ototoxicity and nephrotoxicity. |
■ FDA Black Box Warning
Aminoglycosides like amikacin can cause nephrotoxicity, ototoxicity (vestibular and cochlear), and neuromuscular blockade. Risk increases with prolonged use, high doses, pre-existing renal impairment, and concomitant use of other nephrotoxic or ototoxic drugs. Serum drug levels and renal function should be monitored.
| Serious Effects |
Hypersensitivity to amikacin or any other aminoglycoside; patients with severe renal impairment not on dialysis (relative).
| Precautions | Monitor renal function and drug levels due to narrow therapeutic index; adjust dose for renal impairment; serial audiometry for high-frequency hearing loss; caution in neuromuscular disorders (e.g., myasthenia gravis) due to potential curare-like effect. |
| Food/Dietary | No specific food interactions. Avoid excessive intake of potassium-rich foods if renal impairment is present due to risk of hyperkalemia. |
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| Fetal Monitoring | Maternal: Baseline and serial audiometry, renal function tests (serum creatinine, BUN), urinalysis, and serum drug trough levels. Fetal/neonatal: Hearing screening after birth, renal function assessment if prolonged maternal exposure. |
| Fertility Effects | No known direct effects on human fertility. Animal studies show no impairment at therapeutic doses. |
| Clinical Pearls | BRISTAGEN (gentamicin) is an aminoglycoside antibiotic with concentration-dependent bactericidal activity. Monitor peak (target 5-10 mcg/mL) and trough (<2 mcg/mL) levels to optimize efficacy and reduce nephrotoxicity/ototoxicity risk. Adjust dose based on renal function (CrCl). Avoid concurrent use with other nephrotoxic/ototoxic drugs (e.g., loop diuretics, vancomycin). Extended-interval dosing (e.g., 5-7 mg/kg q24h) is common for Gram-negative infections; adjust interval based on renal function. Obtain culture and sensitivity before initiation. |
| Patient Advice | Take this medication exactly as prescribed; do not skip doses or stop early even if you feel better. · Drink plenty of fluids to stay hydrated unless instructed otherwise by your doctor. · Report any signs of kidney problems (decreased urination, swelling), hearing loss, ringing in ears, dizziness, or numbness/tingling immediately. · This drug may cause neuromuscular blockade; avoid use if you have myasthenia gravis unless specifically advised. · Notify your doctor if you are pregnant, breastfeeding, or planning to become pregnant. · Tell your healthcare provider about all other medications you take, especially water pills (diuretics) or other antibiotics. |