Transdermal enhancement strategy of ketoprofen and teriflunomide: The effect of enhanced drug-drug intermolecular interaction by permeation enhancer on drug release of compound transdermal patch

The aim of the present work was to develop compound transdermal patch containing teriflunomide (TEF) and ketoprofen (KTP) using permeation enhancement strategy; reveal the molecular mechanism by which Azone (AZ) promoted transdermal absorption of compound patch through the enhancement of drug-drug intermolecular interaction. The formulation was optimized using in vitro skin permeation study and confirmed with pharmacodynamics study, anti-inflammatory study and analgesics study. Enhanced drug-drug interaction by AZ was characterized using FT-IR, C-13 NMR, molecular modeling and thermal analysis. The optimized formulation was composed of TEF (3%), KTP (2%), AZ (10%) and DURO-TAK (R) 87-4098 as adhesive matrix. The skin permeation amount of TEF-KTP combination was promoted by AZ about 1.9 times (594.2 +/- 46.8 mu g/cm(2)) and 1.2 times (502.92 +/- 24.0 mu g/cm(2)) compared with TEF-AZ and KTP-AZ individual patch. It was proved that the interaction between TEF and KTP via hydrogen bonding was further enhanced by AZ due to the increased molecular mobility of acrylate polymer (Delta T-g = -17.7 degrees C), which was proved by FTIR and C-13 NMR spectra. The enhanced drug-drug intermolecular interaction increased drug dispersed status and decreased the quantity of drug's hydrogen bonding site, thus increasing the drug release amount significantly. In conclusion, a compound transdermal patch containing KTP and TEF was developed successfully and a novel enhancement mechanism was clarified at molecular level, which provided reference for the development of novel compound transdermal patch.