A SPECTROPHOTOMETRIC METHOD FOR THE DETERMINATION OF PRAZOSIN HYDROCHLORIDE IN TABLETS

Abstract

Prazosin (1) 1-(4-amino-6,7-dimethoxy-2-quizanolinyl)-4-(2-furanylcarbonyl) piperazine is an antihypertensive and a potent vasodilatory agent in the quinazoline family and also has been found to be value in the treatment of heart failure. The drug and its formulations are official in the British Pharmacopeia and United States Pharmacopoeia. There are fluorimetric, UV spectrophotometric, GLC, TLC, voltametric, and differential pulse polarographic13−15 methods in the literature for the assay of the drug. The official USP XXII method uses a HPLC technique for the determination of 1 in capsules . There is no conventional method for the tablets. HPLC is widely used for the assay of the drug in body fluids16−18 and biological samples. There is only one visible-range spectrophotometric method in the literature, and so a simple, time-saving and sensitive method for the assay of prazosin hydrochloride in pharmaceuticals and bulk sample formulations is needed. This paper describes a spectrophotometric method based on the reaction of prazosin hydrochloride with 1,2-naphthoquinone-4-sulphonic acid (NQS) via its amino group on the side chain attached to the 2-position of the dihydropyridine ring. NQS was previously reported to be a sensitive colour reagent for several primary and secondary amines21−23. ∗Corresponding author