Studies on the transdermal delivery of nimodipine from a menthol-based TTS in human volunteers

The purpose of the present study was to design a membrane-moderated transdermal therapeutic system (TTS) of nimodipine using 2%w/w hydroxypropyl methylcellulose (HPMC) gel as a reservoir system containing menthol as penetration enhancer and 60%v/v ethanol-water as solvent system. The flux of nimodipine was markedly increased from 35.51 microg/cm2/h to 167.53+/-3.69 microg/cm2/h with the addition of 8%w/w menthol to HPMC drug reservoir. There was an increase in the flux of nimodipine through ethylene vinyl acetate (EVA) copolymer membrane with an increase in vinyl acetate content (9 to 28%w/w) of the copolymer. The permeability flux of nimodipine from the chosen EVA 2825 (with 28%w/w vinyl acetate content) was 152.05+/-2.68 microg/cm2/h, and this flux decreased to 132.69+/-1.45 microg/cm2/h on application of a water-based acrylic adhesive (TACKWHITE A 4MED) coat. However, the transdermal flux of nimodipine across EVA 2825 membrane coated with TACKWHITE A 4MED/ rat skin composite was found to be 116.05+/-2.39 microg/cm2/h, which is about 1.4 times greater than the required flux. Thus a new transdermal therapeutic system for nimodipine was designed using EVA 2825 membrane coated with a pressure-sensitive adhesive TACKWHITE 4A MED, and 2%w/w HPMC gel as reservoir containing 8%w/w of menthol as a penetration enhancer. The in vivo evaluation of nimodipine TTS patch was carried out to find the ability of the fabricated menthol-based TTS patch in providing the predetermined plasma concentration of the drug in human volunteers. The results showed that the menthol-based TTS patch of nimodipine provided steady plasma concentration of the drug with minimal fluctuations with improved bioavailability in comparison with the immediate release tablet dosage form.