Preparation and biopharmaceutical evaluation of microcapsules of amoxicillin.
Two methods of microencapsulation of amoxicillin, an orally administered antibiotic, were studied. One is based on dispersion of gelatin-amoxicillin mixture in liquid paraffin followed by drying and hardening with formalin-isopropanol treatment; the other is based on dispersion of ethylcellulose-amoxicillin mixture in purified water containing sodium lauryl benzene sulphonate. The microcapsules were recovered as discrete, free-flowing fine granules with a particle diameter of about 250-1000 microns. Dissolution of amoxicillin from ethylcellulose microcapsules was suppressed considerably with a zero-order dissolution pattern in solutions of various pH. Gastric-emptying-controlled rabbits were used for the in vivo evaluation of gelatin and ethylcellulose microcapsules. The ethylcellulose microcapsule containing 25 per cent amoxicillin showed a significantly sustained release pattern of amoxicillin. To establish a suitable design and for the evaluation of the sustained release microcapsules, a nomogram was made using pharmacokinetic parameters obtained after administration of a conventional formulation. It is advantageous for the preparation of sustained release microcapsules to chose pharmaceuticals having over about 2 as the ratio of the elimination rate constant, k10, to the release/absorption rate constant, kr, in the rabbit.
D000042:Absorption; D000284:Administration, Oral; D000658:Amoxicillin / Q000008:administration & dosage* / Q000493:pharmacokinetics; D000818:Animals; D002214:Capsules / Q000008:administration & dosage / Q000378:metabolism; D002482:Cellulose / Q000031:analogs & derivatives; D003692:Delayed-Action Preparations / Q000592:standards; D004339:Drug Compounding / Q000379:methods; D005746:Gastric Emptying; D005780:Gelatin; D007275:Injections, Intravenous; D008855:Microscopy, Electron, Scanning; D008954:Models, Biological; D011817:Rabbits
D002214:Capsules; D003692:Delayed-Action Preparations; C013517:ethyl cellulose; D000658:Amoxicillin; D005780:Gelatin; D002482:Cellulose