title: Influence of admixed citric acid and physiological variables on the vinpocetine release from sodium alginate compressed matrix tablets.
abstract: In this study, the controlled release matrix tablets of vinpocetine were prepared by direct compression using sodium alginate (SAL) as hydrophilic polymer and different amounts of citric acid as hydrosoluble acidic excipient to set up a system bringing about zero-order release of this drug in distilled water containing 0.5% sodium dodecyl sulfate. At the critical content of admixed citric acid (60 mg/tab.), the lowest drug-release rate was observed. In order to explain the effect of this critical content on drug-release rate from SAL matrices, investigation of the possibility of interaction of citric acid with SAL was performed using differential scanning calorimetric analysis and infrared analysis, which confirmed the existence of direct citric acid-SAL interaction when these two excipients came in contact with water. A zero-order drug-release system could be obtained by regulating the ratio of citric acid-to-SAL and the capacity of this system in controlling drug-release rate depended on the extent of interaction between citric acid and SAL. It is worth noticing that pH and the ionic strength of the dissolution medium were found to exert an influence on the drug-release performance of SAL tablets.
authors.affiliation: Department of Pharmaceutical Engineering, Wuhan Bioengineering Institute, Yangluo Economic Development Zone, Wuhan, China. niesf77@163.com
authors.forename: Shufang
authors.initials: S
authors.lastname: Nie
authors.forename: Jie
authors.initials: J
authors.lastname: Wu
authors.forename: Hui
authors.initials: H
authors.lastname: Liu
authors.forename: Weisan
authors.initials: W
authors.lastname: Pan
authors.forename: Yanli
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000464:Alginates / Q000737:chemistry*; D000927:Anticonvulsants / Q000737:chemistry*; D019343:Citric Acid / Q000737:chemistry*; D003692:Delayed-Action Preparations / Q000737:chemistry; D012964:Sodium; D012995:Solubility; D013607:Tablets / Q000737:chemistry*; D013997:Time Factors; D014748:Vinca Alkaloids / Q000737:chemistry*
chemical_list: D000464:Alginates; D000927:Anticonvulsants; D003692:Delayed-Action Preparations; D013607:Tablets; D014748:Vinca Alkaloids; D019343:Citric Acid; C013983:vinpocetine; D012964:Sodium