Griseofulvin is used in the treatment of tineas (ringworm infections) of the skin, hair, and nails, including tinea barbae, tinea capitis, tinea corporis, tinea cruris, tinea pedis, and tinea unguium (onychomycosis) caused by susceptible species of Trichophyton, Microsporum, or Epidermophyton. Because the drug is not effective against other fungal infections, the infecting organism should be identified as a dermatophyte before initiating therapy. Griseofulvin is not effective in the treatment of pityriasis (tinea) versicolor, candidiasis, deep mycotic infections, or bacterial infections, and safety and efficacy of the drug for prophylaxis of fungal infections have not been established. Griseofulvin should not be used indiscriminately, but should be reserved for infections not amenable to topical antifungal agents. Concomitant therapy should include general hygienic measures to control infection and to prevent reinfection. Appropriate agents should also be employed when infections are complicated by the presence of bacteria or yeasts, as may occur in tinea pedis.
Response to therapy depends upon the rate of keratinization and time necessary for desquamation of infected keratinized structures. Soles, palms, and nails respond more slowly than less keratinized skin, and toenails respond at the slowest rate. Although symptomatic improvement of skin infections may be seen after a few days of oral griseofulvin therapy, the drug should be administered until previously infected tissue is devoid of fungi, usually a minimum of 2-4 weeks in the treatment of tinea corporis and a year or longer in the treatment of fungal nail infections. There are no published clinical studies comparing ultramicrosize and microsize griseofulvin for the treatment of tinea infections, and there is no clinical evidence that one formulation has any advantage over the other.
Tinea barbae and tinea capitis generally require treatment with an oral antifungal regimen. Tinea corporis and tinea cruris generally can be effectively treated using a topical antifungal agent; however, an oral antifungal regimen may be necessary if the disease is extensive, dermatophyte folliculitis is present, the infection does not respond to topical therapy, or the patient is immunocompromised or has coexisting disease (e.g., diabetes mellitus). While topical antifungals usually are effective for the treatment of acute, uncomplicated tinea manuum and tinea pedis, an oral antifungal regimen usually is necessary for the treatment of severe, chronic, or recalcitrant tinea pedis, chronic moccasin-type (dry-type) tinea pedis, and for the treatment of tinea unguium (onychomycosis).
In a double-blind study in adults with tinea corporis and/or tinea cruris randomized to receive oral griseofulvin (500 mg once daily) or oral fluconazole (150 mg once weekly) for 4-6 weeks, a clinical cure was obtained in 62 or 74% of patients, respectively.
Oral griseofulvin generally has been considered a drug of choice for treatment of tinea capitis; however, prolonged therapy usually is necessary to cure the infection and poor compliance may affect response to the drug. In a prospective, randomized study in pediatric patients 2-15 years of age with mycologically confirmed tinea capitis who were randomized to receive oral griseofulvin (10 mg/kg daily) or oral terbinafine, the response rate to both drugs was 100%. However, in a retrospective review of pediatric patients 3 months to 12 years of age who received oral griseofulvin (mean dosage: 12.5 mg/kg of microsize once daily for 5 weeks) for treatment of mycologically confirmed tinea capitis, the initial response rate to the drug was 60.7%, and almost 40% of patients had signs and symptoms of persistent disease 8 months after the initial diagnosis.
Because griseofulvin has some vasodilatory activity, its use has resulted in some improvement in a small number of patients with Raynaud's disease or angina pectoris. Because it is structurally similar to colchicine and shares its activity as a metaphase inhibitor, griseofulvin has been used in the treatment of gout.