Overview
DESCRIPTION Griseofulvin tablets, USP (microsize) contain griseofulvin microsize for oral administration. The active ingredient, griseofulvin, is a fungistatic antibiotic, derived from a species of Penicillium. The chemical name of griseofulvin is 7-chloro-2’,4,6-trimethoxy-6’β-methylspiro[benzofuran-2(3H),1’-[2]cyclohexane]-3-4’-dione.
Mechanism of Action
CLINICAL PHARMACOLOGY Griseofulvin absorption from the gastrointestinal tract varies considerably among individuals, mainly because of insolubility of the drug in aqueous media of the upper GI tract. Drug absorption has been estimated to range between 27 and 72%. After an oral dose, griseofulvin is primarily absorbed from the duodenum with some absorption occurring from the jejunum and ileum. The peak serum level in fasting adults given 0.5 g of griseofulvin microsize occurs at about four hours and ranges between 0.5 to 2 mcg/mL. The serum level may be increased by giving the drug with a meal with a high fat content.
Indications
- INDICASTIONS AND USAGE Griseofulvin tablets, USP are indicated for the treatment of dermatophyte infections of the skin not adequately treated by topical therapy, hair and nails, namely: Tinea corporis Tinea pedis Tinea cruris Tinea barbae Tinea capitis Tinea unguium when caused by one or more of the following species of fungi: Epidermophyton floccosum Microsporum audouinii Microsporum canis Microsporum gypseum Trichophyton crateriform Trichophyton gallinae Trichophyton interdigitalis Trichophyton megnini Trichophyton mentagrophytes Trichophyton rubrum Trichophyton schoenleini Trichophyton...
Common Doses
- 0.5 g
- 125 mg
- 250 mg
- 500 mg
Dosage
DOSAGE AND ADMINISTRATION Accurate diagnosis of the infecting organism is essential. Identification should be made either by direct microscopic examination of a mounting of infected tissue in a solution of potassium hydroxide or by culture on an appropriate medium. Medication must be continued until the infecting organism is completely eradicated as indicated by appropriate clinical or laboratory examination. Representative treatment periods are tinea capitis, 4 to 6 weeks; tinea corporis, 2 to 4 weeks; tinea pedis, 4 to 8 weeks; tinea unguium – depending on rate of growth – fingernails, at...
Contraindications
- CONTRAINDICATIONS Griseofulvin is contraindicated in patients with porphyria or hepatocellular failure, and in individuals with a history of hypersensitivity to griseofulvin. Griseofulvin may cause fetal harm when administered to a pregnant woman. Two published cases of conjoined twins have been reported in patients taking griseofulvin during the first trimester of pregnancy, therefore, griseofulvin is contraindicated in women who are or may become pregnant during treatment.
Side Effects
- ADVERSE REACTIONS There have been post-marketing reports of severe skin and hepatic adverse events associated with griseofulvin use (see WARNINGS section). When adverse reactions occur, they are most commonly of the hypersensitivity type, such as skin rashes, urticaria, and rarely, angioneurotic edema, and erythema multiforme. These may necessitate withdrawal of therapy and appropriate countermeasures. Peripheral neuropathy and paresthesias of the hands and feet have been reported and may be related to treatment duration.
Interactions
- Drug Interactions Griseofulvin has been reported in the literature to interfere with the metabolism of various compounds. Whether this is due to a P-450 mediated enzyme induction effects on sulfurtransferase and/or glucotransferase activity, or some other mechanism is unknown. Griseofulvin decreases the activity of warfarin-type anticoagulants, so that patients receiving these drugs concomitantly may require dosage adjustment of the anticoagulant during and after griseofulvin therapy.