Metron

# Metron ## Overview - **Classification**: Nitroimidazole antibiotic and antiprotozoal. - **Mechanism**: Inhibits nucleic acid synthesis by disrupting DNA, leading to cell death in anaerobic bacteria and protozoa. ## Primary Indications 1. **Anaerobic Bacterial Infections**: Intra-abdominal, gynecologic, skin/skin structure, CNS, lower respiratory tract. 2. **Protozoal Infections**: Amoebiasis, giardiasis, trichomoniasis. 3. **_Clostridioides difficile_ Infection (CDI)**: Mild to moderate cases. 4. **_Helicobacter pylori_ Eradication**: As part of multi-drug regimens. ## Adult Dosing ### Standard Dosing **Anaerobic Bacterial Infections** - **Dose**: **500 mg** - **Frequency**: Every **8 hours** - **Route**: Oral or IV - **Duration**: **7-10 days**, or as clinically indicated. **Trichomoniasis** - **Dose**: **2000 mg** (single dose) OR **500 mg** - **Frequency**: Single dose OR twice daily - **Route**: Oral - **Duration**: Single dose OR **7 days** (BID regimen). **Amoebiasis (Intestinal or Hepatic Abscess)** - **Dose**: **500-750 mg** - **Frequency**: Every **8 hours** - **Route**: Oral or IV - **Duration**: **5-10 days** (intestinal), **7-10 days** (hepatic abscess). **_Clostridioides difficile_ Infection (Mild-Moderate)** - **Dose**: **500 mg** - **Frequency**: Every **8 hours** - **Route**: Oral - **Duration**: **10-14 days**. ### Dose Adjustments - **Renal Impairment**: Generally **no dose adjustment** needed, even in ESRD. - **Hemodialysis**: Administer dose **after dialysis** on dialysis days. - **Hepatic Impairment**: Reduce dose by **50%** in severe hepatic dysfunction (Child-Pugh C). - Monitor closely for adverse effects, especially CNS toxicity. - **Elderly Patients**: Use with caution. Consider lower end of dosing range due to potential for decreased hepatic/renal function. ## Pediatric Dosing ### Anaerobic Bacterial Infections ### Neonates (0-28 days) - **Dose**: **7.5 mg/kg** - **Frequency**: Every **12-24 hours** (adjust based on gestational/postnatal age) - **Maximum**: **15 mg/kg/day** - **Special Notes**: Extended dosing intervals common due to immature drug clearance. ### Infants (1-12 months) - **Dose**: **7.5-15 mg/kg** - **Frequency**: Every **8 hours** - **Maximum**: **30 mg/kg/day** ### Children (1-12 years) - **Dose**: **15-35 mg/kg/day** (divided) - **Frequency**: Every **8 hours** - **Maximum**: **4000 mg/day** or adult dose, whichever is less. ### Adolescents (13-18 years) - **Dose**: Adult dosing typically applies. - **Maximum**: **4000 mg/day** ### Amoebiasis (All Pediatric Ages) - **Dose**: **35-50 mg/kg/day** (divided) - **Frequency**: Every **8 hours** - **Maximum**: **2250 mg/day** - **Duration**: **5-10 days**. ### Trichomoniasis (All Pediatric Ages) - **Dose**: **15 mg/kg/day** (divided) - **Frequency**: Every **8 hours** - **Maximum**: **2000 mg/day** - **Duration**: **7 days**. ## Safety Information ### Contraindications - **Absolute**: Hypersensitivity to metronidazole or other nitroimidazole derivatives. - **Absolute**: Pregnancy during first trimester (relative for trichomoniasis, weigh risks/benefits). - **Absolute**: Concurrent use of disulfiram within 14 days (psychotic reactions). - **Absolute**: Concurrent alcohol consumption (disulfiram-like reaction). ### Common Adverse Effects - **Very Common (>10%)**: Nausea, metallic taste, headache. - **Common (1-10%)**: Vomiting, diarrhea, abdominal cramps, dizziness, dark/reddish-brown urine. - **Serious but Rare**: Seizures, peripheral neuropathy (prolonged/high doses), aseptic meningitis, SJS/TEN, neutropenia. ### Key Drug Interactions - **Alcohol**: Disulfiram-like reaction (flushing, vomiting, palpitations). Avoid during therapy and for **3 days after**. - **Warfarin**: Increases anticoagulant effect. Monitor INR closely; reduce warfarin dose if needed. - **Lithium**: Increases lithium levels (decreased renal clearance of lithium). Monitor lithium levels; adjust dose. - **Busulfan**: Increases busulfan toxicity. Avoid concomitant use. - **Phenytoin/Phenobarbital**: May decrease metronidazole levels. ## Monitoring & Follow-up - **Before Treatment**: Obtain baseline CBC for prolonged high-dose therapy. - **During Treatment**: Monitor for CNS toxicity (seizures, neuropathy symptoms). - **Clinical Signs**: Watch for numbness/tingling (neuropathy), rash, severe persistent diarrhea (CDI). ## Clinical Pearls - 💡 **Tip 1**: Administer oral metronidazole with food to minimize GI upset and metallic taste. - 💡 **Tip 2**: Counsel patients to **strictly avoid alcohol** (including alcohol-containing products like mouthwash) during and for at least **3 days** after treatment. - 💡 **Tip 3**: Urine may turn dark or reddish-brown; this is a harmless and expected effect. - 💡 **Tip 4**: IV infusions should be administered slowly over **30-60 minutes**. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.