[Comparative evaluation using in vitro dissolution tests of various sustained release theophylline preparations]

The author's aim was to compare the dissolution properties of the two newly developed sustained release "A" and "B" tablets containing 3,000 mg and 150 mg theophyllin respectively with the similar foreign preparations on the market. The referent preparations are as follows: Theo-Dur (Astra) and Theo-Dur (Recordati) tablets; Euphyllin and Euphyllin minor (Byk Gulden) retard capsules; Euphyllin retard (Byk Gulden) filmcoated tablets and Aminophyllinum-retard (Lek-Ljubljana) tablets. The dissolution tests were carried out by means of the rotating basket apparatus. The "half-change" method was used for testing the dissolution of the preparations. Evaluating the preparations the optimal dissolution rate found in the literature was taken into consideration. The results of the "B" tablet containing 150 mg theophylline were in good agreement with the findings of the preparations on the market and those indicated in the literature. The "A" tablet containing 300 mg active substance showed significantly slower dissolution rate as the comparative preparation did and as it is regarded optimal by the literature.