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Metronidazole, 1 % gel

Drug formSoft

ATC categoryAntiprotozoals

ATC subcategoryNitroimidazole derivatives (for external use)

Brand nameMetronidazole

Generic nameMetronidazole

Composition

Each gram of Metronidazole Denta gel for gums, contains:

active ingredient: metronidazole – 10 mg;

excipients: propylene glycol, carbomer-940, methylparaben, triethanolamine, disodium EDTA, purified water.

Pharmacological group and ATC code
Metronidazole is a 5-nitroimidazole derivative with antibacterial activity. ATC Code: J01XD01.
Chemical name and CAS number
2-(2-Methyl-5-nitro-1H-imidazol-1-yl)ethanol; 443-48-1.

Pharmacology

Metronidazole is an antiprotozoal and antibacterial agent which is active against a wide range of pathogenic micro-organisms. The mechanisms of action of metronidazole in rosacea are unknown but available evidence suggests that the effects may be antibacterial and/or anti-inflammatory.

Pharmacokinetics
The systemic concentration of Metronidazole following the topical administration of 1 g Metronidazole gel to 10 patients with rosacea ranged from 25 ng/ml (limit of detection), to 66 mg/ml with a mean Cmax of 40.6 ng/ml.

The corresponding mean Cmax following the oral administration of a solution containing 30 mg of metronidazole was 850 ng/ml (equivalent to 212 ng/ml if dose corrected. The mean Tmax for the topical formulation was 6.0 hours compared to 0.97 hours for the oral solution.

Uses
Indicated in the treatment of inflammatory papules, pustules and erythema of rosacea.

Dosage and administration
For topical administration only.

The average period of treatment is three to four months. The recommended duration of treatment should not be exceeded. However, if a clear benefit has been demonstrated, continued therapy for a further three to four months period may be considered by the prescribing physician depending on the severity of the condition. In clinical studies, topical metronidazole therapy for rosacea has been continued for up to 2 years. In the absence of a clear clinical improvement, therapy should be stopped.

Adults: Metronidazole Gel should be applied in a thin layer to the affected areas of the skin twice daily, morning and evening. Areas to be treated should be washed with a mild cleanser before application. Patients may use non-comedogenic and non-astringent cosmetics after application of Metronidazole Gel.

Elderly: The dosage recommended in the elderly is the same as that recommended in adults.

Children: Not recommended. Safety and efficacy have not been established.

Contraindications
– Contraindicated in individuals with a history of hypersensitivity to Metronidazole, or other ingredients of the formulation.

Adverse effects

Because of the minimal absorption of metronidazole and consequently its insignificant plasma concentration after topical administration, the adverse experiences reported with the oral form of the drug have not been reported with Metronidazole Gel. Adverse reactions reported with Metronidazole Gel have been only local and mild.

Skin and subcutaneous tissue disorders:

Common: dry skin, erythema, pruritus, skin discomfort (burning, pain of skin/stinging), skin irritation, worsening of rosacea.
Unknown frequency: contact dermatitis.

Watery eyes have been reported if applied too closely to this area.

Precautions

Contact with mucous membranes should be avoided.

Metronidazole Gel has been reported to cause lacrimation of the eyes, therefore, contact with the eyes should be avoided. If a reaction suggesting local irritation occurs patients should be directed to use the medication less frequently or discontinue use temporarily and to seek medical advice if necessary. Metronidazole is a nitroimidazole and should be used with care in patients with evidence of, or history of, blood dyscrasia. Exposure of treated sites to ultraviolet (e.g. solarium, sun-lamp) or strong sunlight (including sun-bathing) should be avoided during use of metronidazole. Metronidazole transforms into inactive metabolite due to UV exposure, therefore its efficacy decreases significantly. Phototoxic side-effects haven’t been reported in clinical trials in relation to metronidazole. Unnecessary and prolonged use of this medication should be avoided.

Pregnancy and breastfeeding
The safety of topically applied metronidazole in pregnancy and lactation has not been adequately established and should not be used in these circumstances unless the physician considers it essential. Patients are advised not to take alcohol during systemic metronidazole therapy because of the possibility of a disulfiram-like reaction.

Some potentiation of anti-coagulant therapy has been reported when metronidazole has been used with the warfarin type oral anticoagulants.

Patients receiving phenobarbitone metabolise metronidazole at a much faster rate than normal, reducing the half-life to 3 hours.

Drug interactions

Patients are advised not to take alcohol during systemic metronidazole therapy because of the possibility of a disulfiram-like reaction.

Some potentiation of anti-coagulant therapy has been reported when metronidazole has been used with the warfarin type oral anticoagulants.

Patients receiving phenobarbitone metabolise metronidazole at a much faster rate than normal, reducing the half-life to 3 hours.

Presentation

Metronidazole, 1% gel is supplied in a aluminum tube (20 g).

Expiry date

3 years. Do not use after the expiration date.

Prescription status

To be dispensed with prescription.

Storage conditions

Store at a room temperature, in a dry place, out of the reach of children. Protect from light.