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# Metronidazole
## Overview
Metronidazole is an antimicrobial agent effective against anaerobic bacteria and certain protozoa.
## Primary Indications
* **Bacterial Vaginosis:** Treatment of bacterial vaginosis.
* **Trichomoniasis:** Treatment of symptomatic trichomoniasis.
* **Amebiasis:** Treatment of intestinal amebiasis.
* **Giardiasis:** Treatment of giardiasis.
* **Anaerobic Bacterial Infections:** Treatment of serious anaerobic bacterial infections, often in combination with other agents.
## Adult Dosing
* **Bacterial Vaginosis:**
* Oral: 500 mg twice daily for 7 days, or 2 g as a single dose.
* Vaginal Gel (0.75%): 5 g applied vaginally once daily for 5 days.
* **Trichomoniasis:**
* Oral: 2 g as a single dose, or 250 mg twice daily for 7 days, or 375 mg twice daily for 7 days.
* **Amebiasis:**
* Intestinal: 500-750 mg orally three times daily for 7-10 days.
* Abscess: 500-750 mg orally three times daily for 7-10 days.
* **Giardiasis:** 250 mg orally three times daily for 5 days.
* **Anaerobic Infections:** 500 mg IV or orally every 8 hours. Duration depends on severity and site of infection, often 7-14 days. Maximum daily dose typically 4 g.
## Pediatric Dosing
* **Trichomoniasis:** Not recommended for children.
* **Amebiasis:**
* Intestinal: 35-50 mg/kg/day orally divided into three doses for 5-10 days. Maximum 750 mg/dose.
* Abscess: 35-50 mg/kg/day orally or IV divided into three doses for 5-10 days. Maximum 750 mg/dose.
* **Giardiasis:** 15 mg/kg/day orally divided into three doses for 5 days. Maximum 250 mg/dose.
* **Anaerobic Infections:** 7.5 mg/kg/dose IV or orally every 8 hours. Maximum 500 mg/dose. Duration varies.
## Dose Adjustments
No specific dose adjustment is generally recommended for hepatic or renal impairment, though caution is advised. In severe hepatic impairment, dosage reduction may be considered.
## Contraindications
* Hypersensitivity to metronidazole or other nitroimidazole derivatives.
* First trimester of pregnancy (oral use) for trichomoniasis.
## Adverse Effects
Common: Nausea, vomiting, diarrhea, metallic taste, headache, dizziness, dark urine.
Serious: Peripheral neuropathy, seizures, Stevens-Johnson syndrome, leukopenia, pancreatitis, disulfiram-like reaction with alcohol.
## Key Drug Interactions
* **Alcohol:** Disulfiram-like reaction (flushing, nausea, vomiting, headache, palpitations). Advise patients to avoid alcohol during therapy and for at least 3 days after completion.
* **Warfarin:** Increased anticoagulant effect. Monitor INR closely.
* **Lithium:** May increase lithium levels, potentially leading to toxicity. Monitor lithium levels.
* **Phenytoin, Phenobarbital:** May decrease metronidazole levels.
* **Busulfan:** Metronidazole may increase busulfan toxicity.
## Monitoring
* Monitor for signs and symptoms of peripheral neuropathy (numbness, tingling, pain).
* Monitor for seizure activity.
* Monitor for signs of hypersensitivity reactions.
* If prolonged therapy, consider CBC.
## Clinical Pearls
* Metronidazole has a metallic taste which can be bothersome for patients.
* Concurrent use of alcohol must be strictly avoided.
* For anaerobic infections, combination therapy is often required.
* Ensure adequate hydration when administering IV metronidazole.
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*Disclaimer: This information is intended for healthcare professionals and does not substitute for professional medical advice. Always consult the most current prescribing information and relevant clinical guidelines before making any treatment decisions.*
