Various alkyl ester prodrugs of diclofenac were synthesized in order to investigate the relationship between their skin permeation characteristics and physicohemical properties. Solubility in various vehicles was meastured at room temperature. 1-Octan...
Various alkyl ester prodrugs of diclofenac were synthesized in order to investigate the relationship between their skin permeation characteristics and physicohemical properties. Solubility in various vehicles was meastured at room temperature. 1-Octanol/water partition coefficients (Log P) and capacity factors (k") were measured to detemine the lipophilicity of the prodrugs. Stability of prodrugs in the skin extract and homogenate was also investigated before conduction the skin permeation studies. Increases in the Log P and capacity factor values were observed when alkyl esters of diclofenac were perpared. Since the aqueous solubility of the prodrugs was not high enough, they were saturated in propylene glycol (PG) for skin permeation studies. Prodrugs were rapidly metabolized to diclofenac, both in skin homogenate and in dernal extract of skin. The skin permeation rate of alkyl ester prodrugs was significantly higher than diclofenac with shorter lag time. Morecover, a parabolic relationship was observed between the pemeation rate and the log P values of prodrugs, and the maximum flux was achieved at a log P value of around 4.0.