Design and evaluation of matrix diffusion controlled transdermal patches of Diltiazem hydrochloride

A matrix dispersion type transdermal drug delivery system of Diltiazem Hydrochloride was developed using different ratios of rosin with Eudragit RL PM and polyvinyl pyrrolidone. The patch prepared by the combination of rosin and polyvinyl pyrrolidone was not transparent one, and shows an uneven distribution of polyvinyl pyrrolidone, which may be due to the hydrophilic nature of polyvinyl pyrrolidone. The effect of the polymers on the technological properties, i.e., drug release, water vapor transmission rate, percentage moisture loss and thickness were investigated. The patch containing rosin: Eudragit RL PM (6:4) showed a release of 2651 mcg in 24 h. In order to improve the release various proportions of camphor was included in the formulation. The patch containing rosin: Eudragit RL PM (6:4) with 5% w/v of camphor showed a sustained release of the drug extending over a period of 24 h. Formulation F8 emerged as the most satisfactory formulation as far as the technological properties were concerned. Further skin permeation and skin irritation studies were carried out on rat skin and rabbit respectively. Therefore it can be concluded that the patch containing rosin: Eudragit RL PM in the ratio 6:4 with 5%w/v of camphor achieved the desired objectives of transdermal drug delivery systems, such as overcoming of first pass effect, extended release and reduced frequency of administration.