Please check your internet connection and try again.
# Metrogyl (metronidazole)
## Overview
Metronidazole is a synthetic nitroimidazole antibiotic effective against anaerobic bacteria and certain protozoa.
## Primary Indications
* **Bacterial infections:** Intra-abdominal infections, skin and soft tissue infections, gynecologic infections, bone and joint infections, CNS infections, lower respiratory tract infections, endocarditis, and septicemia caused by susceptible anaerobic bacteria.
* **Protozoal infections:** Trichomoniasis, amebiasis, and giardiasis.
* **Other:** Bacterial vaginosis, *Clostridioides difficile*-associated diarrhea (CDAD), and as part of *Helicobacter pylori* eradication regimens.
## Adult Dosing
* **Anaerobic bacterial infections:**
* Systemic infections: 500 mg IV or orally every 8 hours.
* Prophylaxis in colorectal surgery: 1 g IV within 12-24 hours before surgery, then 500 mg every 8 hours for up to 24 hours postoperatively.
* Intra-abdominal infections: 500 mg IV or orally every 8 hours.
* *C. difficile*-associated diarrhea: 500 mg orally every 8 hours for 10-14 days.
* **Bacterial vaginosis:** 500 mg orally twice daily for 7 days, or a single 2 g dose orally.
* **Trichomoniasis:**
* Single-dose regimen: 2 g orally once.
* Multi-dose regimen: 250 mg orally three times daily for 7 days, or 375 mg orally twice daily for 7 days.
* **Amebiasis:**
* Intestinal amebiasis: 500-750 mg orally three times daily for 5-10 days.
* Hepatic amebiasis: 500-750 mg orally three times daily for 5-10 days.
* Followed by a luminal agent (e.g., iodoquinol, paromomycin) if invasive disease is present.
* **Giardiasis:** 250 mg orally three times daily for 5-7 days, or 375 mg orally twice daily for 5-7 days.
* ***H. pylori* eradication:** Typically 500 mg orally twice daily in combination with other agents (e.g., PPI, amoxicillin or clarithromycin) for 10-14 days.
*Maximum dose:* Generally 4 g per day for IV administration. For oral use, consider dose adjustments based on indication and patient factors.
## Pediatric Dosing
Dosing varies significantly by indication and weight. Consult specific pediatric guidelines or institutional protocols.
* **Anaerobic bacterial infections:** Doses typically range from 7.5 mg/kg to 15 mg/kg per dose IV or orally every 8 hours.
* Maximum dose: 15 mg/kg per dose or 4 g per day.
* **Intestinal amebiasis:** 35-50 mg/kg/day orally divided into 3 doses for 5-10 days.
* **Intra-abdominal infections:** 7.5 mg/kg per dose IV or orally every 8 hours.
* **Giardiasis:** 5 mg/kg per dose orally three times daily for 5-7 days (maximum 250 mg/dose).
## Dose Adjustments
* **Renal impairment:** No dose adjustment is typically needed in mild to moderate renal impairment. In severe renal impairment (CrCl < 10 mL/min), the maintenance dose may be halved, or the dosing interval may be doubled. However, data is limited, and clinical monitoring is crucial. Metronidazole and its metabolites are removed by hemodialysis.
* **Hepatic impairment:** Reduce the maintenance dose by 25-50% in severe hepatic disease.
## Contraindications
* Hypersensitivity to metronidazole or other nitroimidazole derivatives.
* Use of disulfiram within the past 2 weeks.
* Concomitant use of alcohol during and for at least 3 days after therapy 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), Stevens-Johnson syndrome, toxic epidermal necrolysis, neutropenia, pancreatitis, thrombophlebitis (with IV administration).
* **Disulfiram-like reaction:** Flushing, throbbing headache, nausea, vomiting, sweating, chest pain, palpitations, dyspnea when taken with alcohol.
## Key Drug Interactions
* **Alcohol:** Disulfiram-like reaction.
* **Disulfiram:** May cause psychotic reactions.
* **Warfarin:** Potentiates anticoagulant effect. Monitor INR closely.
* **Lithium:** May increase lithium levels, leading to toxicity.
* **Phenytoin, Phenobarbital:** May decrease metronidazole levels.
* **5-Fluorouracil (5-FU):** Metronidazole may increase the toxicity of 5-FU.
* **Busulfan:** Metronidazole may increase busulfan levels, leading to busulfan toxicity.
## Monitoring
* Monitor for signs and symptoms of peripheral neuropathy (numbness, tingling, pain) and CNS toxicity (seizures, confusion).
* Monitor complete blood count (CBC) with differential, especially with prolonged treatment.
* Monitor liver function tests periodically.
* Monitor INR if used concurrently with warfarin.
* Monitor lithium levels if used concurrently with lithium.
## Clinical Pearls
* Administer IV metronidazole over 30-60 minutes to reduce the risk of thrombophlebitis.
* Advise patients to avoid alcohol during and for at least 3 days after treatment.
* The metallic taste is common and can be managed with sugar-free gum, candy, or mouthwash.
* Metronidazole can cause urine to turn a reddish-brown color.
* For *C. difficile* infection, oral administration is preferred. IV may be used if oral administration is not possible.
---
*Please verify this information with the most current prescribing information or relevant clinical guidelines.*
