Effect of fatty acid Esters on permeation of ketoprofen through hairless rat skin

Twelve medium to long chain fatty acid Esters (Esters), the total number of carbon atoms of which ranged from 17 to 34, were used to study the effect of the vehicle on the permeation of ketoprofen, and the effect was compared with the case of indomethacin. The solubility of ketoprofen was higher in Esters with a smaller number of carbon atoms. The permeation rate of ketopr ofen from the Ester suspension through excised hairless rat skin was propor tional to its solubility in the suspension, which was the same in the case of indomethacin. The diffusion constant and partition coefficient were calc ulated using the computer program MULTI(FILT). The diffusion constant decre ased with increasing number of carbon atoms: and the partition coefficient was increased with increasing number of carbon atoms, in both cases of keto profen and indomethacin. Esters also penetrated the skin with the concentra tion of about 10 mg/g, independent of the number of carbon atoms. The Ester s in the skin increase the diffusion rate of the drugs, especially in the c ase of Esters with a small number of carbon atoms. Also the drug solubility in the skin was improved, although the effect was similar for the range of Esters investigated in the present study. Then the permeation rate of keto profen and indomethacin increased. (C) 2000 Elsevier Science B.V. All right s reserved.