title: The preparation and characterization of ethylcellulose-walled theophylline microcapsules.
abstract: The use of sustained-release preparations of theophylline has become routine in the treatment of bronchial asthma. Microencapsulation provides a possible means of producing such a product. The present paper examines, by means of triangular diagrams, the phases present in the system ethylcellulose-petroleum ether-toluene. The separated cellulose was used to coat the drug theophylline. The effects of temperature, petroleum ether fraction, solvent:non-solvent ratio and rate of non-solvent addition on the size and size distribution of the microcapsules was studied.
mesh_terms: D000473:Alkanes; D002214:Capsules; D002482:Cellulose / Q000031:analogs & derivatives*; D002626:Chemistry, Pharmaceutical; D003692:Delayed-Action Preparations; D004339:Drug Compounding / Q000379:methods; D010316:Particle Size; D012995:Solubility; D013696:Temperature; D013806:Theophylline; D014050:Toluene
chemical_list: D000473:Alkanes; D002214:Capsules; D003692:Delayed-Action Preparations; D014050:Toluene; C013517:ethyl cellulose; D002482:Cellulose; D013806:Theophylline; C004544:naphtha