Class: Antifungal Microsize
- Tablets 500 mg (as microsize)
- Tablets 125 mg (as ultramicrosize)
- Tablets 250 mg (as ultramicrosize)
Deposited preferentially into infected skin, which gradually sloughs off and is replaced by noninfected tissue; binds tightly to new keratin, which becomes highly resistant to fungal invasions.
C max is 0.5 to 1.5 mcg/mL. T max is about 4 h.Food
A high-fat meal may increase C max . Microsize is 25% to 70% absorbed. Ultramicrosize is about 100% absorbed.
Mainly deposited in the keratin layer of skin, hair, and nails.
Hepatic. Major metabolites are 6-methyl-griseofulvin and its glucuronide conjugate.
The t ½ is about 24 h. Primarily renal excretion. About 36% is excreted unchanged in the feces.
Indications and Usage
Treatment of ringworm infections of skin, hair, and nails caused by susceptible fungi.
Porphyria; hepatic disease.
Dosage and AdministrationAdults
PO 500 to 1,000 mg microsize (330 to 750 mg ultramicrosize) in single or divided doses. May need to give for several weeks.Children
PO 11 mg microsize/kg/day (125 to 500 mg) or 7.3 mg ultramicrosize/kg/day (82.5 to 330 mg).
- Administer with or after meals, particularly with fatty foods if not contraindicated.
- Generally administered in conjunction with topical agent.
- Do not interchange griseofulvin microsize with ultramicrosize because dosage is different.
Store between 36° to 86°F.
Effects of alcohol may be potentiated with tachycardia and flushing.Anticoagulants
Anticoagulant effect may be decreased.Barbiturates
May depress griseofulvin serum levels.Contraceptives, oral
May cause loss of contraceptive effectiveness.
Laboratory Test Interactions
False elevation of vanillylmandelic acid test assayed by photometric tests but not with gas or thin layer chromatography method.
Headache; fatigue; dizziness; insomnia; confusion; paresthesias.
Nausea; vomiting; epigastric distress; diarrhea; GI bleeding.
Interferes with porphyrin metabolism.
Category C .
Drug may need to be discontinued. Also, penicillin cross-sensitivity is possible, although some penicillin-sensitive patients have used without difficulty.
May exacerbate lupus or lupus-like syndrome.
- Advise patient to inspect skin for signs of improvement of infection or reinfection.
- Explain importance of good hygiene, particularly to affected areas.
- Inform patient that beneficial effects of drug may not be observable for weeks to months.
- Instruct patient to report these symptoms to health care provider: fever, sore throat, skin rash.
- Caution patient to avoid intake of alcoholic beverages or other CNS depressants.
- Advise patient that drug may cause dizziness and to use caution while driving or performing other tasks requiring mental alertness.
- Caution patient to avoid exposure to sunlight and to use sunscreen or wear protective clothing to avoid photosensitivity reaction.
Copyright © 2009 Wolters Kluwer Health.