Pharmacology: Pharmacodynamics: Micotran contains miconazole nitrate, an imidazole derivative antifungal drug. Miconazole nitrate has a broad spectrum of activity and is particularly effective against pathogenic fungi and yeasts including Candida albicans. In addition, it is effective against gram-positive bacteria.
Miconazole nitrate shows its effect during ergosterol synthesis present on cell cytoplasmic membrane. Miconazole nitrate changes permeability of mycotic cell Candida species in vitro and inhibits the glucose consumption of the cell.
Pharmacokinetics: Absorption: Miconazole persists in the vagina for up to 72 hrs after a single dose. Systemic absorption of miconazole after intravaginal administration is limited, with a bioavailability of 1-2% following intravaginal administration of a 1.2 g dose. Plasma concentrations of miconazole are measurable within 2 hrs of administration in some subjects, with maximal levels seen 12-24 hrs after administration. Plasma concentrations decline slowly, thereafter and were still measurable in most subjects 96 hrs post-dose. Absorption of miconazole nitrate by the intravaginal route is very low (approximately 1.4% of dose).
Distribution: Following the insertion of vaginal suppository containing miconazole nitrate 1.2 g in a single dose, the average maximum serum concentration is 10.4 mcg/L, and the elimination half-life (t½) is 56.8 hrs. The average serum concentration-time curve has been calculated to be 967 mcg/L/hr. Protein-binding ratio is between 90% and 93%.
Biotransformation: It is metabolized in liver microsomally. There are no active metabolites. The major metabolite formed by oxidative-N-dealkylation is 2,4-diclorophenile-1 H imidazole ethanol and secondary metabolite is oxidative 2,4-dicloromandelic acid by O-dealkylation.
Elimination: Half-life is 24 hrs. Less than 1% is excreted in the urine. Approximately 50%, is usually excreted with feces as unchanged drug.