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Action/Kinetics:
Derived from a species of
Penicillium. Believed to interfere with cell division (metaphase) or DNA replication. When taken systemically, the drug is deposited in the newly formed skin and nails, which are then resistant to reinfection by the tinea. Absorbed from the duodenum.
Peak plasma concentration: 0.5-2 mcg/mL after 4 hr.
t
1/2: 9-24 hr. Levels may be increased by giving the drug with a high-fat diet. GI absorption of the ultramicrosize products is about 1.5 times that of the microsize products; is no evidence this causes any difference in the safety and effectiveness of the drug compared with the microsize form.
Uses:
Tinea (ringworm) infections of skin (including athlete's foot), scalp, groin, and nails. Effective against tinea corporis, tinea pedis, tinea barbae, tinea unguium, tinea cruris, tinea capitis due to
Trichophyton species,
Microsporum audouinii, M. canis, M. gypseum and
Epidermophyton floccosum. It is the only PO drug effective against dermatophytid (tinea ringworm) infections. Not effective against
Candida. Establish susceptibility of the infectious agent before treatment is begun.
Contraindications:
Pregnancy. Porphyria or history thereof, hepatocellular failure, and hypersensitivity to drug. Exposure to artificial light or sunlight. Use for infections due to bacteria, candidiasis, actinomycosis, sporotrichosis, tinea versicolor, histoplasmosis, chromoblastomycosis, coccidioidomycosis, cryptococcosis, and North American blastomycosis.
Special Concerns:
Cross sensitivity with penicillin is possible.
Side Effects:
Hypersensitivity: Rashes, urticaria,
angioneurotic edema allergic reactions.
GI: N&V;, diarrhea, epigastric pain,
GI bleeding.
CNS: Dizziness, headache, confusion, mental fatigue, insomnia.
Miscellaneous: Oral thrush, acute intermittent porphyria, paresthesias of extremities after long-term therapy, proteinuria, leukopenia, photosensitivity, worsening of lupus erythematosus, menstrual irregularities, hepatic toxicity, granulocytopenia.
Laboratory Test Alterations:
ALT, AST, alkaline phosphatase, BUN, and creatinine level values.
Drug Interactions:
-
Alcohol, ethyl / Tachycardia and flushing
-
Anticoagulants, oral /
Anticoagulant effect R/T
liver breakdown
-
Barbiturates /
Effect of griseofulvin R/T
GI tract absorption
-
Cyclosporine /
Plasma cyclosporine levels
pharmacologic effect
-
Oral contraceptives /
Oral contraceptive effect
breakthrough bleeding, pregnancy, or amenorrhea
-
Salicylates /
Serum salicylate levels
How Supplied:
Griseofulvin microsize:
Capsule: 250 mg;
Suspension: 125 mg/5 mL;
Tablet: 250 mg, 500 mg.
Griseofulvin ultramicrosize:
Tablet: 125 mg; 165 mg; 250 mg; 330 mg
Dosage
?Capsules, Oral Suspension, Tablets
Tinea corporis, cruris, or capitis.
Adults: 0.5 g griseofulvin microsize daily in a single dose or divided dose (or 330-375 mg ultramicrosize).
Tinea pedis or unguium.
Adults: 0.75-1 g/day of griseofulvin microsize (or 660-750 mg ultramicrosize). After response, decrease dose of microsize to 0.5 g/day.
Pediatric, 13.6-22.7 kg: 125-250 mg griseofulvin microsize daily (or 82.5-165 mg ultramicrosize);
pediatric, over 22.7 kg: 250-500 mg microsize daily (or 165-330 mg ultramicrosize).
NOTE: Dose has not been determined in children less than 2 years of age.
