Pharmacology: Pharmacodynamics: Ketoconazole is a synthetic derivative of imidazole-dioxolane, providing fungicidal and fungistatic activity against dermatophytes (Epidermophyton spp., Microsporum spp., Trichophyton spp.) yeast and yeast-like fungi of different strains (Candida spp., Malassezia furfur-Pitysporum ovale).
When applied externally zinc pyrithione suspension has antimicrobial and antifungal activity; effective towards streptococci, staphylococci, fungi and several other pathogens. Zinc pyrithione determines anti-seborrheic effect of the drug and acts against dandruff. Shampoo with ketoconazole reduces flaking and itching, which is often associated with dandruff, seborrheic dermatitis and tinea versicolor.
Pharmacokinetics: Ketoconazole was not detected in plasma in 39 patients who shampooed 4-10 times per week for 6 months or in patients who shampooed 2-3 times per week for 3-26 months. Twelve hours after a single shampoo, hair samples taken from six patients showed that high amounts of ketoconazole were present on the hair; only about 5% had penetrated into the hair keratin. There were no detectable plasma levels after chronic shampooing twice weekly for two months with ketoconazole.