On the bioavailability of topical formulations of clindamycin hydrochloride

The role of the vehicle in the percutaneous absorption of clindamycin hydrochloride has been studied. Fourteen vehicles have been examined for their ability (1) to adequately solubilize clindamycin and (2) to effect penetration of the drug into the skin. The solubility of clindamycin was found to be good in ten of the fourteen vehicles studied, with a drug concentration of greater than 1.0% being achieved. A vehicular water content of greater than 20% or the presence of another suitable cosolvent appeared to be necessary for adequate solubilization of drug. Percutaneous absorption varied greatly among the vehicles, ranging from 0.7% to 12.9% of the applied dose in 24 hours. The vehicles effecting the greatest clindamycin absorption contained the penetration enhancers dimethylsulfoxide or N-methyl-2-pyrrolidone. Overall, the vehicles studied varied a hundredfold with respect to clindamycin bioavailability. Correlation of these data with other literature data suggests a possible relationship between clindamycin bioavailability and clinical efficacy in the treatment of acne and, therefore, argues against extemporaneous compounding of this drug in the absence of bioavailability data.