Abstract
Sustained-release tablets (SR-tablet), prepared with hydrogenated soya phospholipids, gave slow release of theophylline and sodium diclofenac into a solvent at pH 6.8, in an in vitro study. The release profile of theophylline from the SR-tablet remained unchanged at pH values between 2.0 and 6.8. However, the release of diclofenac from the SR-tablet into a solvent at pH 2.0 was very slight, due to the low solubility at pH 2.0. The release of both drugs seems to occur predominantly by a leaching mechanism, as proposed by Higuchi. The oral administration of SR-tablets to dogs avoided a transient peak of drug concentration in the plasma and maintained plasma drug concentrations at higher levels for a longer period, in comparison with the oral administration of theophylline in suspension form or a commercial tablet of sodium diclofenac.
