Metrogyl

# Metrogyl ## Overview - **Classification**: Nitroimidazole antibiotic, antiprotozoal. - **Mechanism**: Enters anaerobic cells, reduced by electron transfer proteins, forming reactive nitro radicals that damage DNA, leading to cell death. ## Primary Indications 1. **Anaerobic bacterial infections**: Intra-abdominal, skin/soft tissue, gynecological, lower respiratory tract. 2. **Protozoal infections**: Amebiasis, giardiasis, trichomoniasis. 3. **_Clostridioides difficile_ infection (CDI)**: Mild to moderate cases. ## Adult Dosing ### Standard Dosing **Anaerobic Bacterial Infections** (e.g., intra-abdominal, skin/soft tissue) - **Dose**: **500 mg** - **Frequency**: Every **8 hours** - **Route**: Oral (PO) or Intravenous (IV) - **Duration**: 7-10 days, or as clinically indicated. **Trichomoniasis** - **Dose**: **2 grams** (single dose) OR **500 mg** - **Frequency**: PO, **twice daily** - **Duration**: 7 days **Amebiasis (Intestinal and Hepatic Abscess)** - **Dose**: **500 mg** to **750 mg** - **Frequency**: PO, **three times daily** - **Duration**: 5-10 days **_Clostridioides difficile_ Infection (Mild to Moderate)** - **Dose**: **500 mg** - **Frequency**: PO, **three times daily** - **Duration**: 10-14 days ### Dose Adjustments - **Renal Impairment**: No adjustment for CrCl >10 mL/min. For CrCl <10 mL/min, **decrease dose by 50%**. Administer **after hemodialysis**. - **Hepatic Impairment**: For severe impairment (Child-Pugh C), **reduce dose by 50-70%**; monitor for adverse effects. - **Elderly Patients**: No specific adjustment, but monitor closely for adverse effects, especially with hepatic impairment. ## Pediatric Dosing ### Neonates (0-28 days) **Anaerobic Bacterial Infections** - **Dose**: **7.5 mg/kg/dose** - **Frequency**: Every **12 hours** (GA >32 weeks) OR Every **24 hours** (GA ≤32 weeks) - **Maximum**: Individual dose should not exceed **500 mg**. - **Special Notes**: Use with caution due to immature hepatic metabolism. ### Infants (1-12 months) **Anaerobic Bacterial Infections** - **Dose**: **7.5-15 mg/kg/dose** - **Frequency**: Every **8 hours** - **Maximum**: **500 mg/dose** **Amebiasis** - **Dose**: **35-50 mg/kg/day** (divided into 3 doses) - **Frequency**: Every **8 hours** - **Maximum**: **750 mg/dose** ### Children (1-12 years) **Anaerobic Bacterial Infections** - **Dose**: **7.5-15 mg/kg/dose** - **Frequency**: Every **8 hours** - **Maximum**: **500 mg/dose** **Trichomoniasis** - **Dose**: **15 mg/kg/day** (divided into 3 doses) - **Frequency**: Every **8 hours** - **Maximum**: **250 mg/dose** **Amebiasis** - **Dose**: **35-50 mg/kg/day** (divided into 3 doses) - **Frequency**: Every **8 hours** - **Maximum**: **750 mg/dose** ### Adolescents (13-18 years) - **Dose**: Use **adult dosing** guidelines. - **Maximum**: **2 grams** single dose or **500 mg three times daily**. ## Safety Information ### Contraindications - **Absolute**: Hypersensitivity to metronidazole or other nitroimidazole derivatives. - **Absolute**: Concomitant use with disulfiram (within 14 days). - **Absolute**: Concomitant use with alcohol or propylene glycol during and for **at least 3 days after** treatment. ### Common Adverse Effects - **Very Common (>10%)**: Nausea, metallic taste. - **Common (1-10%)**: Headache, dizziness, diarrhea, abdominal cramps, vomiting. - **Serious but Rare**: Seizures, peripheral neuropathy (prolonged use), encephalopathy, aseptic meningitis, Stevens-Johnson Syndrome. ### Key Drug Interactions - **Alcohol/Disulfiram**: Disulfiram-like reaction. **Avoid alcohol** during and for **3 days post-treatment**. Avoid disulfiram for **14 days prior**. - **Warfarin**: Enhances anticoagulant effect, increasing bleeding risk. **Monitor INR closely**, adjust warfarin dose. - **Lithium**: May increase serum lithium levels, leading to toxicity. **Monitor lithium levels**. - **Phenytoin/Phenobarbital**: May decrease metronidazole efficacy by increasing metabolism. **Monitor for therapeutic effect**. ## Monitoring & Follow-up - **Before Treatment**: Review complete blood count (CBC) if prolonged therapy expected. - **During Treatment**: Monitor for CNS toxicity (seizures, encephalopathy), peripheral neuropathy. - **Clinical Signs**: Watch for numbness/tingling, gait instability, vision changes, confusion, rash. ## Clinical Pearls - 💡 **Tip 1**: Administer with food or milk to minimize GI upset and metallic taste. - 💡 **Tip 2**: Counsel patients to **strictly avoid alcohol** and alcohol-containing products during and for at least **3 days after** treatment. - 💡 **Tip 3**: IV metronidazole should be infused slowly over **30-60 minutes**. - 💡 **Tip 4**: Discontinue immediately if signs of CNS toxicity or peripheral neuropathy develop. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.