Effect of terpenes on skin permeation of non-ionized and ionized ketotifen

Thc permeability coefficient of ketotifen increased with increase in pH of donor solution, suggesting that skin permeation of ketotifen was virtually obeyed the pH-partition theory, although the contribution of the ionized form of ketotifen cannot be neglected Pretreatment with 2% d-limonene for 1 hour enhanced the permeability coefficient of non-ionized and ionized ketotifen. On the other hand, 1 hour pretreatment with 2% l-menthol slightly increased the non-ionized ketotifen value, bird greatly enhanced the ionized ketotifen value. The pH in the receiver solution after the permeation study was decreased by l-menthol pretreatment. After pretreatment with l-menthol, the permeability coefficient of ionized form of ketotifen and monovalent ionized form of fumaric acid was similar. A possible mechanism is that relatively hydrophobic ion-pair would be formed between rite ionized form of ketotifen nod monovalent ionized form of fumaric acid and the resultant ion-pair could permeate through the hydrophobic route in rite stratum corneum. Pretreatment with terpenes caused no leaching of lipids.