title: Carboxymethyl high amylose starch as excipient for controlled drug release: mechanistic study and the influence of degree of substitution.
abstract: Sodium carboxymethyl high amylose starch, CMHAS(Na), with a DS up to 1.74 were synthesized in non-aqueous medium (with yields as high as 72%) in order to investigate the influence of the degree of substitution (DS) on physical and drug release properties. The CMHAS(Na) was converted to protonated form, CMHAS(H), by acid treatment. The DS and conversion of CMHAS(Na) to CMHAS(H) had a major impact on the physical properties of CMHAS particles and resulting tablets. Dissolution tests performed in simulated gastric fluid (SGF, pH 1.2) and in simulated intestinal fluid (SIF, pH 6.8), with acetaminophen as drug model (20% loading) showed CMHAS as a pH sensitive hydrophilic matrix whereas CMHAS(Na) seems suitable as controlled release matrix. CMHAS(Na) with DS between 0.1 and 0.2 can be preferably used as sustained release excipient since in both dissolution media, the drug release was driven by diffusion over a period up to 12 h. CMHAS(Na) with high DS, between 0.9 and 1.2, can be used as delayed release excipient since drug release in SGF was driven by diffusion over a period up to 20 h and in SIF by fast erosion lowering to less than 3 h the complete release of the drug.
authors.affiliation: Department of Chemistry and Centre Pharmaqam, Université du Québec à Montréal, CP 8888, Succ. A, Montréal, Québec, Canada H3C 3P8.
authors.forename: Marc
authors.initials: M
authors.lastname: Lemieux
authors.forename: Patrick
authors.initials: P
authors.lastname: Gosselin
authors.forename: Mircea Alexandru
authors.initials: MA
authors.lastname: Mateescu
mesh_terms: D000082:Acetaminophen / Q000737:chemistry*; D000688:Amylose / Q000031:analogs & derivatives* / Q000737:chemistry; D002626:Chemistry, Pharmaceutical; D003692:Delayed-Action Preparations; D004058:Diffusion; D004337:Drug Carriers; D004339:Drug Compounding; D005079:Excipients / Q000737:chemistry*; D005750:Gastric Juice / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007419:Intestinal Secretions / Q000737:chemistry; D007700:Kinetics; D010316:Particle Size; D012995:Solubility; D013499:Surface Properties; D013607:Tablets; D014867:Water / Q000737:chemistry
chemical_list: D003692:Delayed-Action Preparations; D004337:Drug Carriers; D005079:Excipients; D013607:Tablets; D014867:Water; C027357:carboxymethylamylose; D000082:Acetaminophen; D000688:Amylose