The aim of this thesis was to study the interaction between sodium lauryl sulfate (SDS) and hydroxypropyl methylcellulose (HPMC). Specifically how this interaction influences the release of diclofenac sodium (Na-DF) from matrix tablets with HPMC. The release of Na-DF from matrix tablets was tested in apparatus 2 (USP) in diluted Mcllvain buffers (DMB) with different pH and SDS concentrations from 0,05-1 %. The percentage of Na-DF released in DMB pH 4 with 0,05 % SDS and DMB pH 7 with 0,05 % SDS was smaller than in DMB media without SDS.
During the dissolution testing, the swelling of tablets was examined by measuring their height and diameter. The 4 hour test in DMB pH 3 and pH 4 showed the volume of tablets increased until the concentration of SDS reached 0,05 %, afterward the volume started to decrease. In DMB pH 7 the volume decreased until 0,05 % of SDS, then started increasing reaching the peak at 0,1 % and then decreased again. When examining the swelling of tablets without Na-DF in DMB pH 3 the volume increased until 0,06 % of SDS and decreased with higher SDS concentrations.
Using the conductometric method the critical micelle concentrations (CMC) of SDS in water and DMB pH 4 was determined. The same media with added HPMC were used to determine the critical aggregation concentration (CAC) and polymer saturation point (PSP). CMC values in water were higher than in DMB pH 4. With higher HPMC concentrations CAC values in water changed nonlinearly while PSP values increased. In DMB pH 4, CAC values increased with higher HPMC concentrations and PSP values changed nonlinearly.
Solubility of Na-DF was determined in DMB media with different pH, with and without HPMC and with different SDS concentrations. In DMB pH 3 and pH 4 media with and without HPMC, the solubility increased with higher SDS concentrations. The addition of HPMC in media increased the solubility of Na-DF in comparison with media without HPMC.
By measuring the transmittance of samples in DMB pH 3 with different SDS and HPMC concentrations, the transmitance was found to decrease with higher SDS and HPMC concentrations until 0,1 % of SDS. When concentrations of SDS increased above 0,1 % the transmittance increased. We noticed unexpected results at similar SDS concentrations (0,05-0,1 %) at all experimental methods we used, which can indicate possible interactions between SDS and HPMC at these concentrations.