Summary.

The aim of this study was to create and optimize matrix sustained release systems, containing a drug with weak basic properties. Verapamil hydrochloride was chosen as model drug. Developed matrix systems were based on Kollidon® SR (BASF) as matrix carrier separately or in combination with other excipients. Throughout the course of the study, it was established that Kollidon® SR (nonionogenic and pH independent matrix) was not suitable for being used separately for the sustained release of Verapamil hydrochloride. More precise control of dissolution rate of the drug can be achieved by adding of hydrophilic excipients. The inclusion of succinic acid to this type of matrix did not give the expected result – increasing of dissolution rate of the drug. Models based on combinations of Kollidon® SR with Lactosa and StarLac can be considered as optimal models.