title: Zero-order release of theophylline from a core-in-cup tablet in sequenced simulated gastric and intestinal fluid.
abstract: Core-in-cup tablets containing theophylline were evaluated for their dissolution characteristics in sequenced simulated gastric fluid (SGF) followed by simulated intestinalfluid (SIF). Core-in-cup tablets containing 10% w/w, 20% w/w, and 30% w/w acacia as binder were evaluated for their effects on the time course of release of theophylline. This was done to optimize a formula that could release theophylline at a zero-order rate of release for 8-16 hr in simulated gastrointestinal fluids. Theophylline was released and dissolved from the core-in-cup tablets at a rate that is more consistent with a zero-order dissolution rate than a first-order dissolution rate in both SIG and SIF. The dissolution rates of theophylline from the 10%, 20%, and 30% acacia core-in-cup tablets were 0.87 mg/min, 0.53 mg/min, and 0.27 mg/min, respectively in SGF, and 0.61 mg/min, 0.30 mg/min, and 0.20 mg/min, respectively in SIF. The results indicate that a concentration of 32% w/w acacia in the core tablet will release theophylline at a rate of 0.14 mg/min in SGF for 2 hr followed by SIF for 10 hr.
authors.affiliation: Department of Pharmacy, Medical School, University of the Witwatersrand, 7 York Road, Parktown 2193, Johannesburg, Republic of South Africa.
authors.forename: M P
authors.initials: MP
authors.lastname: Danckwerts
authors.forename: J G
authors.initials: JG
authors.lastname: van der Watt
authors.forename: I
authors.initials: I
authors.lastname: Moodley
mesh_terms: D000284:Administration, Oral; D002626:Chemistry, Pharmaceutical / Q000379:methods; D003692:Delayed-Action Preparations; D005750:Gastric Juice / Q000378:metabolism*; D013607:Tablets; D013806:Theophylline / Q000008:administration & dosage / Q000493:pharmacokinetics*; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000493:pharmacokinetics*
chemical_list: D003692:Delayed-Action Preparations; D013607:Tablets; D014665:Vasodilator Agents; D013806:Theophylline