pH-independent sustained release matrix tablet containing doxazosin mesylate: Effect of citric acid

• Published in: Archives of pharmacal research Vol. 33; no. 12; pp. 2003 - 2009
• Main Authors: Cha, Kwang-Ho, Tran, Thanh-Huyen, Kim, Min-Soo, Kim, Jeong-Soo, Park, Hee Jun, Park, Junsung, Cho, Wonkyung, Hwang, Sung-Joo
• Format: Journal Article
• Language: English
• Published: Heidelberg Pharmaceutical Society of Korea 01.12.2010; 대한약학회
• Subjects: Adrenergic alpha-1 Receptor Antagonists - administration & dosage; Adrenergic alpha-1 Receptor Antagonists - chemistry; Alginates - chemistry; Citric Acid - chemistry; Delayed-Action Preparations; Doxazosin - administration & dosage; Doxazosin - chemistry; Drug Compounding; Drug Delivery Systems; Glucuronic Acid - chemistry; Hexuronic Acids - chemistry; Hydrogen-Ion Concentration; Medicine; Pharmacology/Toxicology; Pharmacy; Polyethylene Glycols - chemistry; Solubility; Tablets; 약학; pH-Independent; Polyethylen oxide; Citric acid; Doxazosin mesylate
• ISSN: 0253-6269; 1976-3786
• DOI: 10.1007/s12272-010-1216-z

The aim of this study was to develop a pH-independent sustained release matrix tablets of doxazosin mesylate. The matrix tablets were prepared by direct compression technique using polyethylene oxide, sodium alginate and citric acid as a pH modifier. Formulations were evaluated for an in vitro drug release study, erosion study, and the microenvironmental pH was studied using the pH indicator methyl red. For formulations without citric acid, the extent and rate of drug release in simulated gastric fluid were much higher than those in simulated intestinal fluid. By adding the citric acid, the drug release rate in simulated intestinal fluid was increased, and microenvironmental pH values within the tablets were maintained at low pH during drug release. Furthermore, drug release from the matrix tablet containing 20% w/w citric acid was comparable to that from a commercial product, Cardura® XL, and a pHindependent release could be achieved. Therefore, the incorporation of citric acid as a pH modifier to Polyethylen oxide-sodium alginate matrix tablets effectively produced pHindependent doxazocin mesylate release profiles.