Metrogyl%252525252525252525252525252525252525252525252525252520%252525252525252525252525252525252525252525252525252528metronidazole%252525252525252525252525252525252525252525252525252529

# Metrogyl (metronidazole) ## Overview Metronidazole is an antimicrobial agent effective against anaerobic bacteria and certain parasites. ## Primary Indications * **Bacterial Vaginosis:** Treatment of bacterial vaginosis. * **Trichomoniasis:** Treatment of urogenital trichomoniasis. * **Amoebiasis:** Treatment of amoebic infections (intestinal and extraintestinal). * **Giardiasis:** Treatment of giardiasis. * **Anaerobic Bacterial Infections:** Various anaerobic bacterial infections, including intra-abdominal infections, gynecologic infections, skin and soft tissue infections, bone and joint infections, CNS infections, lower respiratory tract infections, and endocarditis. * **Pseudomembranous Colitis:** Treatment of *Clostridioides difficile*-associated diarrhea. * **Surgical Prophylaxis:** Prophylaxis against anaerobic infection in specific surgical procedures. * **H. pylori Eradication:** Part of combination therapy for *Helicobacter pylori* eradication. ## Adult Dosing * **Bacterial Vaginosis:** 500 mg orally twice daily for 7 days, OR 2 grams orally as a single dose. * **Trichomoniasis:** 2 grams orally as a single dose, OR 200-400 mg orally twice daily for 7-10 days. * **Amoebiasis (Intestinal):** 500-750 mg orally three times daily for 5-10 days. * **Amoebiasis (Extra-intestinal):** 500-750 mg orally three times daily for 5-10 days. * **Giardiasis:** 250 mg orally three times daily for 5 days, OR 500 mg orally twice daily for 7-10 days. * **Anaerobic Bacterial Infections:** 500 mg intravenously or orally every 8 hours. Duration varies based on infection severity and site, typically 7-14 days. * **Pseudomembranous Colitis:** 250-500 mg orally four times daily or 500 mg orally three times daily. Duration typically 10-14 days. * **Surgical Prophylaxis:** 1 gram orally or intravenously 1-2 hours before surgery, followed by 500 mg orally or intravenously every 8 hours for up to 24 hours post-operatively. * **H. pylori Eradication:** Dosing varies widely within combination regimens, often 500 mg orally twice daily in conjunction with other agents. **Maximum dose:** Generally, 4 grams per day for adults. ## Pediatric Dosing Specific dosing requires careful consideration of indication, weight, and severity. Dosing below is typical but may vary; consult specific pediatric guidelines or local protocols. * **Trichomoniasis/Giardiasis:** 15 mg/kg orally as a single dose (maximum 2 grams), OR 5 mg/kg orally every 8 hours for 7 days. * **Amoebiasis:** * **Intestinal:** 35-50 mg/kg/day orally divided into 3 doses for 5-10 days (maximum 750 mg/dose or 2 grams/day). * **Extra-intestinal:** 35-50 mg/kg/day orally divided into 3 doses for 5-10 days (maximum 750 mg/dose or 2 grams/day). * **Anaerobic Bacterial Infections:** * **Intravenous:** 7.5 mg/kg every 8 hours, OR 30 mg/kg/day divided every 6 or 8 hours (maximum 4 grams/day). * **Oral:** 15-30 mg/kg/day divided every 8 hours (maximum 4 grams/day). * **Bacterial Vaginosis:** Not typically recommended in children. * **H. pylori Eradication:** Dosing within combination regimens requires specific pediatric guidelines. ## Dose Adjustments * **Hepatic Impairment:** Reduce maintenance dose by 50% in severe hepatic impairment. Monitor for toxicity. * **Renal Impairment:** No dose adjustment needed for hemodialysis or peritoneal dialysis for standard dosing. For severe renal impairment (CrCl < 10 mL/min), maintaining the usual dose is generally acceptable, but some sources suggest reducing the dose by 50% if the interval is extended. ## Contraindications * Hypersensitivity to metronidazole or other nitroimidazole derivatives. * First trimester of pregnancy (relative contraindication, especially for systemic use). * Concurrent use with disulfiram or alcohol (due to disulfiram-like reaction). ## Adverse Effects * **Common:** Nausea, vomiting, diarrhea, abdominal pain, metallic taste, headache, dizziness. * **Serious:** Peripheral neuropathy (especially with prolonged use), central nervous system effects (seizures, encephalopathy, cerebellar toxicity), Stevens-Johnson syndrome, toxic epidermal necrolysis, erythema multiforme, anaphylaxis, pancreatitis, hepatotoxicity, drug reaction with eosinophilia and systemic symptoms (DRESS). * **Disulfiram-like reaction:** Flushing, headache, nausea, vomiting, palpitations, and shortness of breath with alcohol consumption. * **Darkening of urine:** Harmless, but can be mistaken for hematuria. ## Key Drug Interactions * **Alcohol:** Disulfiram-like reaction. Avoid alcohol during and for at least 3 days after treatment. * **Disulfiram:** Risk of psychotic reactions. Avoid concurrent use. * **Warfarin:** Potentiates anticoagulant effect. Monitor INR and adjust warfarin dose as needed. * **Lithium:** May increase lithium levels, leading to toxicity. Monitor lithium levels. * **Phenytoin/Phenobarbital:** May decrease metronidazole levels. * **5-Fluorouracil (5-FU):** Metronidazole may increase the toxicity of 5-FU; monitor for myelosuppression and mucositis. ## Monitoring * **Clinical response:** Assess for improvement in signs and symptoms of infection. * **Neurological status:** Monitor for signs of peripheral neuropathy or CNS toxicity, especially with prolonged therapy. * **Liver function tests:** Consider baseline and periodic monitoring in patients with pre-existing liver disease or those on prolonged therapy. * **Renal function:** Especially in elderly patients or those with known renal impairment. * **INR:** If patient is on warfarin. ## Clinical Pearls * Effective against anaerobic bacteria and protozoa. * Distinct metallic taste is common and usually well-tolerated, but can affect medication adherence. * Advise patients to avoid alcohol during and for at least 3 days after treatment due to the potential for a disulfiram-like reaction. * Neurological adverse effects, including peripheral neuropathy and CNS toxicity, are rare but serious and can be irreversible. Promptly discontinue therapy if neurological symptoms develop. * Treatment for *C. difficile* should be guided by severity and local resistance patterns. * Use during pregnancy should be carefully weighed against potential risks, particularly in the first trimester. *** **Disclaimer:** This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the current prescribing information and relevant guidelines for complete and up-to-date information before prescribing or administering any medication.