KETOCONAZOLE

Ketoconazole is an azole antifungal that inhibits replication of yeast cells by interfering with the synthesis of ergosterol, a vital component of the cell membrane. It is available as a 2 per cent shampoo.

The shampoo is used twice a week for two to four weeks; it should be left on the hair for three to five minutes on each application. The condition can then be controlled with weekly or fortnightly use.

It appears to be extremely safe to use. Ketoconazole has not been detected in plasma following topical use, and the shampoo does not cause the adverse effects and interactions associated with systemic use. Skin irritation has been reported only very rarely. It is not contraindicated in pregnancy.

PYRITHIONE ZINC AND SELENIUM SULPHIDE

Both compounds are cytostatic agents, which act by reducing the rate of epidermal cell turnover. The action of pyrithione zinc is thought to involve a non-specific toxicity for epidermal cells, whereas selenium sulphide is believed to have a direct antimitotic effect.