Griseofulvin
Pronouncation: (griss-ee-oh-FULL-vin)Class: Antifungal Microsize
Trade Names:
Grifulvin V
- Tablets 500 mg (as microsize)
Trade Names:
Gris-PEG
- Tablets 125 mg (as ultramicrosize)
- Tablets 250 mg (as ultramicrosize)
Pharmacology
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Feedback for Griseofulvin
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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.
Pharmacokinetics
Absorption
C max is 0.5 to 1.5 mcg/mL. T max is about 4 h.
FoodA high-fat meal may increase C max . Microsize is 25% to 70% absorbed. Ultramicrosize is about 100% absorbed.
Distribution
Mainly deposited in the keratin layer of skin, hair, and nails.
Metabolism
Hepatic. Major metabolites are 6-methyl-griseofulvin and its glucuronide conjugate.
Elimination
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.
Contraindications
Porphyria; hepatic disease.
Dosage and Administration
AdultsPO 500 to 1,000 mg microsize (330 to 750 mg ultramicrosize) in single or divided doses. May need to give for several weeks.
ChildrenPO 11 mg microsize/kg/day (125 to 500 mg) or 7.3 mg ultramicrosize/kg/day (82.5 to 330 mg).
General Advice
- 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.
Storage/Stability
Store between 36° to 86°F.
Drug Interactions
AlcoholEffects of alcohol may be potentiated with tachycardia and flushing.
AnticoagulantsAnticoagulant effect may be decreased.
BarbituratesMay depress griseofulvin serum levels.
Contraceptives, oralMay 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.
Adverse Reactions
CNS
Headache; fatigue; dizziness; insomnia; confusion; paresthesias.
Dermatologic
Rash; urticaria.
EENT
Oral thrush.
GI
Nausea; vomiting; epigastric distress; diarrhea; GI bleeding.
Genitourinary
Proteinuria.
Hematologic
Leukopenia; granulocytopenia.
Hepatic
Hepatic toxicity.
Metabolic
Interferes with porphyrin metabolism.
Miscellaneous
Angioneurotic edema.
Precautions
Pregnancy
Category C .
Lactation
Undetermined.
Hypersensitivity
Drug may need to be discontinued. Also, penicillin cross-sensitivity is possible, although some penicillin-sensitive patients have used without difficulty.
Lupus
May exacerbate lupus or lupus-like syndrome.
Patient Information
- 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.
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More Griseofulvin resources:
Gris-PEG Ultramicrosize Tablets
Griseofulvin - Includes detailed dosage instructions.
Griseofulvin Drug Interactions
Onychomycosis -- Toenail, Tinea Corporis, Tinea Pedis, Tinea Cruris, Onychomycosis -- Fingernail, Tinea Capitis, Tinea Barbae
