Metronidazole
Metronidazole (Flagyl)
Metronidazole
(meh-troh- NYE-dah-zohl)
Pregnancy Category: B Apo-Metronidazole Femazole Flagyl Flagyl 500 Injection Flagyl ER Flagyl I.V. Flagyl I.V. RTU Metric 21 Metro-Cream Topical MetroGel Topical MetroGel-Vaginal Metro I.V. MetroLotion Metryl Metryl-500 Metryl I.V. NidaGel Noritate Cream 1% Novo-Nidazol PMS-Metronidazole Protostat Satric Satric 500 Trikacide (Rx)

Classification: Systemic trichomonacide, amebicide

See Also: See also Anti-Infectives .

Action/Kinetics: Effective against anaerobic bacteria and protozoa. Specifically inhibits growth of trichomonae and amoebae by binding to DNA, resulting in loss of helical structure, strand breakage, inhibition of nucleic acid synthesis, and cell death. Well absorbed from GI tract and widely distributed in body tissues. Peak serum concentration: PO, 6-40 mcg/mL, depending on the dose, after 1-2 hr. t 1/2: PO, 6-12 hr average: 8 hr. Eliminated primarily in urine (20% unchanged), which may be red-brown in color following either PO or IV use. The mechanism for its effectiveness in reducing the inflammatory lesions of acne rosacea is not known.

Uses: Systemic: Amebiasis. Symptomatic and asymptomatic trichomoniasis; to treat asymptomatic partner. Amebic dysentery and amebic liver abscess. To reduce postoperative anaerobic infection following colorectal surgery, elective hysterectomy, and emergency appendectomy. Anaerobic bacterial infections of the abdomen, female genital system, skin or skin structures, bones and joints, lower respiratory tract, and CNS. Also, septicemia, endocarditis, hepatic encephalopathy. PO for Crohn's disease and pseudomembranous colitis. As part of the regimen to eradicate Helicobacter pylori infections. Investigational: Giardiasis, Gardnerella vaginalis.
Topical: Inflammatory papules, pustules, and erythema of rosacea. Investigational: Infected decubitus ulcers (use 1% solution prepared from oral tablets).
Vaginal: Bacterial vaginosis.

Contraindications: Blood dyscrasias, active organic disease of the CNS, trichomoniasis during the first trimester of pregnancy, lactation. Topical use if hypersensitive to parabens or other ingredients of the formulation. Consumption of alcohol during use.

Special Concerns: Safety and efficacy have not been established in children.

Side Effects: Systemic Use. G I: Nausea, dry mouth, metallic taste, vomiting, diarrhea, abdominal discomfort, constipation. CNS: Headache, dizziness, vertigo, incoordination, ataxia, confusion, irritability, depression, weakness, insomnia, syncope, seizures, peripheral neuropathy including paresthesias. Hematologic: Leukopenia, bone marrow aplasia. GU: Burning, dysuria, cystitis, polyuria, incontinence, dryness of vagina or vulva, dyspareunia, decreased libido. Allergic: Urticaria, pruritus, erythematous rash, flushing, nasal congestion, fever, joint pain. Miscellaneous: Furry tongue, glossitis, stomatitis (due to overgrowth of Candida) ECG abnormalities, thrombophlebitis.
Topical Use: Watery eyes if gel applied too closely to this area; transient redness; mild burning, dryness, and skin irritation.
Vaginal Use: Symptomatic candida vaginitis, N&V.

Overdose Management: Symptoms: Ataxia, N&V, peripheral neuropathy, seizures up to 5-7 days. Treatment: Supportive treatment.

Drug Interactions: Barbiturates / Possible therapeutic failure of metronidazole Cimetidine / Serum metronidazole levels R/T clearance Disulfiram / Concurrent use may cause confusion or acute psychosis Ethanol / Possible disulfiram-like reaction, including flushing, palpitations, tachycardia, and N&V Hydantoins / Hydantoins effect R/T clearance Lithium / Lithium toxicity Warfarin / Anticoagulant effect

How Supplied: Capsule: 375 mg; Cream: 0.75%, 1%; Gel/Jelly/Lotion: 0.75%; Injection: 500 mg/100 mL; Tablet: 250 mg, 500 mg; Tablet, Extended-Release: 750 mg

Dosage
?Capsules, Tablets Amebiasis: Acute amebic dysentery or amebic liver abscess.
Adult: 500-750 mg t.i.d. for 5-10 days; pediatric: 35-50 mg/kg/day in three divided doses for 10 days.
Trichomoniasis, female.
250 mg t.i.d. for 7 days, 2 g given on 1 day in single or divided doses, or 375 mg b.i.d. for 7 days. Pediatric: 5 mg/kg t.i.d. for 7 days. An interval of 4-6 weeks should elapse between courses of therapy. NOTE: Do not treat pregnant women during the first trimester. Male: Individualize dosage; usual, 250 mg t.i.d. for 7 days.
Treat Helicobacter pylori infections.
One of the following regimens may be used: (1) Metronidazole, 500 mg b.i.d.; clarithromycin, 500 mg b.i.d.; and, either lansoprazole, 30 mg b.i.d. or omeprazole, 20 mg b.i.d. All drugs given for 2 weeks. (2) Metronidazole, 500 mg b.i.d. for 2 weeks, or amoxicillin, 1 g b.i.d. for 2 weeks, or tetracycline, 500 mg b.i.d. for 2 weeks; plus, clarithromycin, 500 mg b.i.d. for 2 weeks and ranitidine bismuth citrate, 400 mg b.i.d. for 4 weeks. (3) Tetracycline, 500 mg q.i.d.; metronidazole, 500 mg t.i.d.; bismuth subsalicylate, 525 mg q.i.d; and, either lansoprazole, 30 mg once daily or omeprazole, 20 mg once daily. All drugs given for 2 weeks. (4) Tetracycline, 500 mg q.i.d.; metronidazole, 250 mg q.i.d.; bismuth subsalicylate, 525 mg q.i.d.; and, a H2-receptor antagonist. Drugs are given for 2 weeks except for the H2-receptor antagonist which is given for 4 weeks.
Giardiasis.
250 mg t.i.d. for 7 days.
G. vaginalis.
500 mg b.i.d. for 7 days.
?Tablets, Extended-Release Bacterial vaginosis.
One 750-mg tablet per day for 7 days.
?IV Anaerobic bacterial infections.
Adults, initially: 15 mg/kg infused over 1 hr; then, after 6 hr, 7.5 mg/kg q 6 hr for 7-10 days (daily dose should not exceed 4 g). Treatment may be necessary for 2-3 weeks, although PO therapy should be initiated as soon as possible.
Prophylaxis of anaerobic infection during surgery.
Adults: 15 mg/kg given over a 30- to 60-min period, with completion 1 hr prior to surgery and 7.5 mg/kg infused over 30-60 min 6 and 12 hr after the initial dose.
?Topical (0.75%, 1%) Rosacea.
After washing, apply a thin film and rub in well either once daily or b.i.d. in the morning and evening for 4-9 weeks.
?Vaginal (0.75%) Bacterial vaginosis.
One applicatorful (5 g) in the morning and evening for 5 days. Metro-Gel Vaginal allows for once-daily dosing at bedtime.