Dithranol

Dithranol has been used in the treatment of sub-acute and chronic psoriasis for over 70 years and, during that time it has become established as a safe and effective form of therapy. Its precise mode of action is still to be confirmed, although it has been shown to inhibit DNA replication, cellular respiration and key cellular enzymes eg glucose-6-phosphate dehydrogenase.

Because dithranol causes staining and irritation, it is now widely used in short contact therapy where the preparation is washed off the skin after periods of one hour or less. For this purpose, dithranol cream is particularly suitable, as it is convenient to apply and washes off easily in a bath or shower.

The traditional formulations of dithranol are based on soft paraffin from which it is effectively released into the skin. In dithranol cream, during manufacture, the oily paraffin phase of the cream is heated until the dithranol entirely dissolves so that, on cooling, it is retained solely within the paraffin phase and does not spread into the aqueous phase. After application of dithranol cream to the skin, the water is lost through absorption and evaporation, leaving the oily phase which then acts in the same way as a dithranol ointment. However, since the cream may be rubbed into the skin more effectively than the ointment, it is convenient to apply and, owing to the presence of the emulsifying components, is easier to wash off. The availability of the dithranol has now been confirmed in numerous publications detailing the results of clinical trials.

No special information.