METROGYL

What it is

Metrogyl is an intravaginal dosage form of the synthetic antibacterial agent metronidazole, a member of the imidazole class of antibacterial agents. The vaginal gel formulation contains metronidazole 0.75% w/w, with each 5 g applicator containing approximately 37.5 mg of metronidazole. The gel is formulated at the normal vaginal pH of 4.0.

Approved indications

— Symptomatic bacterial vaginosis in patients where other pathogens have been ruled out.

Dosing overview

The recommended dose is one applicator full of Metrogyl (approximately 5 g containing approximately 37.5 mg of metronidazole) intravaginally once a day, at bedtime, for 5 days.

Key safety warnings

Approximately 6–10% of patients treated with Metrogyl developed symptomatic Candida vaginitis during or immediately after therapy, which may be due to known or previously unrecognised vulvovaginal candidiasis presenting with more prominent symptoms during therapy. Metrogyl contains ingredients that may cause burning and irritation of the eye; in the event of accidental contact with the eye, rinse the eye with copious amounts of cool tap water. Some patients treated with oral or intravenous metronidazole have been reported to have convulsive seizures or peripheral neuropathy characterised mainly by numbness or paraesthesia of an extremity; while the occurrence of serious neurological symptoms with Metrogyl is unlikely, the appearance of abnormal neurological signs should prompt discontinuation of therapy. Metrogyl should be administered with caution to patients with central nervous system diseases. Cases of severe hepatotoxicity or acute hepatic failure with fatal outcomes have been reported with metronidazole in patients with Cockayne syndrome; in this population, metronidazole should be used after careful benefit-risk assessment and if no alternative treatment is available. Some patients treated with oral metronidazole have been observed to have mild transient leukopenia; Metrogyl should be administered with caution to patients with evidence of or a history of blood dyscrasia. Although oral metronidazole concurrent with alcohol may result in a disulfiram-like reaction, despite the relatively low serum levels of metronidazole produced following administration of Metrogyl, the possibility of a disulfiram-like reaction to alcohol whilst on Metrogyl cannot be excluded and patients should be cautioned about drinking alcohol while being treated.

Contraindications

Metrogyl is contraindicated for patients with a prior history of hypersensitivity to metronidazole, hydroxybenzoates, other ingredients of the formulation or other nitroimidazole derivatives.

Regulatory history

Metrogyl (vaginal gel formulation) was first approved on 28 March 2000. The Metrogyl tablet formulations (200 mg and 400 mg) were first listed on the ARTG on 20 September 1991.