1. Transdermal drug delivery systems for antihypertensive drugs - A review

Hypertension is one of the largest deaths causing disease for the mankind. Since it is a chronic disease it necessitates long term treatment. The disadvantages of antihypertensive drugs such as more frequent of administration, extensive first pass metabolism and variable bioavailability, make it is an ideal candidate for transdermal drug delivery systems. This article is dedicated to the review of antihypertensive transdermal patches in the perspective of enhancing the bioavailibity as well as in improving the patient compliance. The various antihypertensive drugs considered in the review includes timolol maleate, nicardipine hydrochloride, captopril, atenolol, metoprolol tartrate, clonidine, indapamide, labetolol, pinacidil, verapamil hydrochloride, nitrendipine, nifedipine, nicorandil, propranolol hydrochloride, diltiazem hydrochloride, amlodipine besilate, carvedilol and lisinopril. Clonidine was the first antihypertensive drug developed in the transdermal form. Currently a number of antihypertensive transdermal patches are introduced in to the pharmaceutical market. Most of the reported methods in the literature employed solvent evaporation method or solvent casting method for the preparation of transdermal patches. Depending on the release required over a period of time, the concentrations of polymer, plasticizer and penetrant were varied.