METRONIDAZOLE IN PLASTIC CONTAINER
Clinical safety rating: safe
Disulfiram-like reaction can occur with alcohol Can cause peripheral neuropathy and seizures with prolonged use.
After intracellular reduction, metronidazole and its metabolites interact with DNA leading to inhibition of nucleic acid synthesis and cell death. It is active against anaerobic bacteria and protozoa.
| Metabolism | Hepatic metabolism primarily via oxidation, conjugation; main metabolite: hydroxy metabolite (active). Enzymes: CYP450 (minor). |
| Excretion | Renal (60-80% as unchanged drug and metabolites), fecal (6-15%), biliary (<5%) |
| Half-life | 8 hours (range 6-12 hours) in adults with normal hepatic function; prolonged to 15-30 hours in severe liver disease |
| Protein binding | Less than 20%, primarily to albumin |
| Volume of Distribution | 0.6-0.8 L/kg, indicating extensive tissue penetration |
| Bioavailability | Oral: approximately 80% (range 60-100%); IV: 100% |
| Onset of Action | IV: immediate; oral: 1-2 hours; topical: 2-6 hours |
| Duration of Action | 12-24 hours; dosing typically every 6-8 hours for systemic infections |
500 mg IV every 8 hours or 7.5 mg/kg IV every 6 hours (loading dose 15 mg/kg) for most anaerobic infections.
| Dosage form | INJECTABLE |
| Renal impairment | GFR > 50 mL/min: No adjustment; GFR 10-50 mL/min: 500 mg IV every 12 hours; GFR < 10 mL/min: 500 mg IV every 24 hours or 250 mg IV every 12 hours; Hemodialysis: Administer 500 mg IV post-dialysis; Peritoneal dialysis: Usual dose or 250 mg IV every 12 hours. |
| Liver impairment | Child-Pugh A: No adjustment; Child-Pugh B: Reduce dose by 50% every 8 hours or administer 500 mg IV every 12-16 hours; Child-Pugh C: Avoid use or use with extreme caution, monitor levels. |
| Pediatric use | Neonates (<7 days): 7.5 mg/kg IV every 12-24 hours based on gestational age; Infants 7-28 days: 7.5 mg/kg IV every 8-12 hours; Children (≥1 month): 30 mg/kg/day IV divided every 6 hours, maximum 4 g/day. |
| Geriatric use | No specific dose adjustment required, but monitor renal function; reduce dose based on creatinine clearance as per renal adjustment; consider increased risk of adverse effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Disulfiram-like reaction can occur with alcohol Can cause peripheral neuropathy and seizures with prolonged use.
| FDA category | Human |
| Breastfeeding | Enters breast milk; M/P ratio 0.9-1.3. Avoid high doses (single 2g); moderate doses (250-500mg) compatible; monitor infant for diarrhea or oral thrush. |
| Teratogenic Risk | Metronidazole crosses the placenta. First trimester: limited data; avoid unless essential. Second/third trimesters: no increased risk of major malformations reported; use if clearly needed. |
■ FDA Black Box Warning
Carcinogenicity: Metronidazole has been shown to be carcinogenic in mice and rats. Relevance to humans is unknown. Avoid unnecessary use.
| Common Effects | protozoal infections |
| Serious Effects |
["Hypersensitivity to metronidazole or other nitroimidazole derivatives","Pregnancy (first trimester) for trichomoniasis (controversial)","Use of disulfiram within the last two weeks (psychotic reactions)"]
| Precautions | ["Carcinogenicity risk (avoid chronic use)","Seizures and peripheral neuropathy (discontinue if abnormal neurologic signs occur)","Hepatic impairment: use with caution, monitor for toxicity","Renal impairment: no dose adjustment usually needed, but monitor for accumulation","Drug interactions with warfarin (increased INR), disulfiram-like reaction with alcohol","Pregnancy category B: use only if clearly needed","Lactation: caution, metronidazole excreted in breast milk"] |
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| Fetal Monitoring | Maternal: CBC, liver function tests if prolonged use. Fetal: no specific monitoring; standard prenatal care. |
| Fertility Effects | No evidence of impaired fertility in humans; animal studies show no effect. |