Pharmacokinetic evaluation in dogs of theophylline in a novel zero-order release cone-in-cup tablet

A new core-in-cup tablet that is manufactured from a novel adjustable punch, has been formulated and evaluated for its ability to release with subsequent absorption of theophylline via a zero-order rate of absorption. The core-in-cup tablets were compared with core only tablets and immediate release capsules. Pharmacokinetic parameters used to test the effectiveness of the formulations included, elimination rate, rate and kinetic order of absorption, relative availability as compared with an immediate release capsule of pure theophylline, and percentage area under the curve fluctuation (%AUCF) at steady state. The correlation coefficient, Akaike's information criterion (AIC) and the F-ratio probability were used to test the applicability of a zero-order, first-order, or square root of time model, for the rate of release of theophylline from the core-in-cup and core only tablets. The zero-order rate model was most applicable to the core-in-cup tablet, whereas the square root of time release model was most applicable to the core only tablet. The average %AUCF for the core-in-cup tablet was 9.26 +/- 3.15 while that for the core only tablet was 16.19 +/- 2.37 (p = 0.0545). The results of this study suggest that the core-in-cup tablet is a versatile zero-order release rate dosage form that are simple to produce. (C) 1998 John Wiley & Sons, Ltd.