Introduction
An antifungal antibiotic. Griseofulvin may be given by mouth in the treatment of tinea infections.
Uses
Griseofulvin is an antifungal agent used to treat a variety of superficial tinea infections and fungal infections of the fingernails and toes.
For the treatment of ringworm infections of the skin, hair, and nails, namely: tinea corporis, tinea pedis, tinea cruris, tinea barbae, cradle cap or other conditions caused by Trichophyton or Microsporum fungi.
Associated Conditions
Pharmacodynamics
Griseofulvin is a mycotoxic metabolic product of Penicillium spp. It was the first available oral agent for the treatment of dermatophytoses and has now been used for more than forty years. Griseofulvin is fungistatic with in vitro activity against various species of Microsporum Epidermophyton, and Trichophyton. It has no effect on bacteria or on other genera of fungi. Following oral administration, griseofulvin is deposited in the keratin precursor cells and has a greater affinity for diseased tissue. The drug is tightly bound to the new keratin which becomes highly resistant to fungal invasions. Once the keratin-Griseofulvin complex reaches the skin site of action, it binds to fungal microtubules (tubulin) thus altering fungal mitosis.
Mechanism of Action
Griseofulvin is fungistatic, however the exact mechanism by which it inhibits the growth of dermatophytes is not clear. It is thought to inhibit fungal cell mitosis and nuclear acid synthesis. It also binds to and interferes with the function of spindle and cytoplasmic microtubules by binding to alpha and beta tubulin. It binds to keratin in human cells, then once it reaches the fungal site of action, it binds to fungal microtubes thus altering the fungal process of mitosis.
Absorption
Poorly absorbed from GI ranging from 25 to 70% of an oral dose. Absorption is significantly enhanced by administration with or after a fatty meal.
Half Life
9-21 hours
Toxicity
Side effects are minor: headaches, gastrointestinal reactions and cutaneous eruptions
Food Interactions
- Avoid alcohol.
- Take with a high fat meal.
Dosage
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 least 4 months; toenails, at least 6months.
General measures in regard to hygiene should be observed to control sources of infection or reinfection. Concomitant use of appropriate topical agents is usually required, particularly in treatment of tinea pedis since in some forms of athlete's foot, yeasts and bacteria may be involved. Griseofulvin will not eradicate the bacterial or monilial infection.
Adults: A daily dose of 500 mg will give a satisfactory response in most patients with tinea corporis, tinea cruris, and tinea capitis. For those fungus infections more difficult to eradicate such as tinea pedis and tinea unguium, a daily dose of 1.0 gm is recommended.
Children: Approximately 5 mg per pound of body weight per day is an effective dose for most children. On this basis the following dosage schedule for children is suggested:
- Children weighing 30 to 50 pounds: 125 mg to 250 mg daily.
- Children weighing over 50 pounds: 250 mg to 500 mg daily.