Clotrimazole and Betamethasone Dipropionate

LOTRISONE® Cream has been shown to be at least as effective as clotrimazole alone in a different cream vehicle. No comparative studies have been conducted with LOTRISONE® Lotion and clotrimazole alone. Use of corticosteroids in the treatment of a fungal infection may lead to suppression of host inflammation leading to worsening or decreased cure rate.

Clotrimazole

Skin penetration and systemic absorption of clotrimazole following topical application of LOTRISONE Cream or Lotion have not been studied. The following information was obtained using 1% clotrimazole cream and solution formulations. Six hours after the application of radioactive clotrimazole 1% cream and 1% solution onto intact and acutely inflamed skin, the concentration of clotrimazole varied from 100 mcg/cm³ in the stratum corneum, to 0.5 to 1 mcg/cm³ in the reticular dermis, and 0.1 mcg/cm³ in the subcutis. No measurable amount of radioactivity (<0.001 mcg/mL) was found in the serum within 48 hours after application under occlusive dressing of 0.5 mL of the solution or 0.8 g of the cream. Only 0.5% or less of the applied radioactivity was excreted in the urine.

Microbiology

Mechanism of Action: Clotrimazole is an imidazole antifungal agent. Imidazoles inhibit 14-α-demethylation of lanosterol in fungi by binding to one of the cytochrome P-450 enzymes. This leads to the accumulation of 14-α- methylsterols and reduced concentrations of ergosterol, a sterol essential for a normal fungal cytoplasmic membrane. The methylsterols may affect the electron transport system, thereby inhibiting growth of fungi.

Activity In Vivo: Clotrimazole has been shown to be active against most strains of the following dermatophytes, both in vitro and in clinical infections as described in the INDICATIONS section: Epidermophyton floccosum, Trichophyton mentagrophytes, and Trichophyton rubrum.

Activity In Vitro: In vitro, clotrimazole has been shown to have activity against many dermatophytes, but the clinical significance of this information is unknown.

Drug Resistance: Strains of dermatophytes having a natural resistance to clotrimazole have not been reported. Resistance to azoles including clotrimazole has been reported in some Candida species.

No single-step or multiple-step resistance to clotrimazole has developed during successive passages of Trichophyton mentagrophytes.

Betamethasone Dipropionate

Betamethasone dipropionate, a corticosteroid, has been shown to have topical (dermatologic) and systemic pharmacologic and metabolic effects characteristic of this class of drugs.

Pharmacokinetics

The extent of percutaneous absorption of topical corticosteroids is determined by many factors, including the vehicle, the integrity of the epidermal barrier and the use of occlusive dressings (see DOSAGE AND ADMINISTRATION). Topical corticosteroids can be absorbed from normal intact skin. Inflammation and/or other disease processes in the skin may increase percutaneous absorption of topical corticosteroids. Occlusive dressings substantially increase the percutaneous absorption of topical corticosteroids (see DOSAGE AND ADMINISTRATION).

Once absorbed through the skin, the pharmacokinetics of topical corticosteroids are similar to systemically administered corticosteroids. Corticosteroids are bound to plasma proteins in varying degrees. Corticosteroids are metabolized primarily in the liver and are then excreted by the kidneys. Some of the topical corticosteroids and their metabolites are also excreted into the bile.

Studies performed with LOTRISONE Cream and Lotion indicate that these topical combination antifungal/corticosteroids may have vasoconstrictor potencies in a range that is comparable to high potency topical corticosteroids. Therefore, use is not recommended in patients less than 17 years of age, in diaper dermatitis, and under occlusion.

Clinical Sudies (LOTRISONE® Cream)

In clinical studies of tinea corporis, tinea cruris, and tinea pedis, patients treated with LOTRISONE Cream showed a better clinical response at the first return visit than patients treated with clotrimazole cream. In tinea corporis and tinea cruris, the patient returned 3 to 5 days after starting treatment, and in tinea pedis, after 1 week. Mycological cure rates observed in patients treated with LOTRISONE Cream were as good as or better than in those patients treated with clotrimazole cream. In these same clinical studies, patients treated with LOTRISONE Cream showed better clinical responses and mycological cure rates when compared with patients treated with betamethasone dipropionate cream.

Clinical Sudies (LOTRISONE® Lotion)

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