The purpose of this work was to study swelling and release behaviour from hydroxypropyl methylcellulose tablets in dissolution media of pH between 3 and 5 to which we added various concentrations of one of the surfactants - anionic sodium lauryl sulfate or nonionic polysorbate 20. We wanted to see how the interaction between sodium lauryl sulfate and hydroxypropyl methylcellulose reflects in the release of well and poorly water-soluble drugs (paracetamol or sodium diclofenac) and in the swelling of the matrix tablets with hydroxypropyl methylcellulose. The behaviour of the tablets was also studied in media with added polysorbate 20, in which interactions with the polymer were not expected. The swelling of the tablets was monitored with dissoGUARD® camera system during the dissolution tests on a paddle apparatus. The swelling of the tablets without a drug was also observed under the same conditions and the results were compared with those obtained from the tablets containing one of the drugs listed above. After 4 hours in a medium, the tablets without a drug were weighed in order to examine the change in tablet mass and correlate the results with the results of swelling.
The results of the release and swelling indicate the different effects of selected surfactants. The interaction between sodium lauryl sulfate and hydroxypropyl methylcellulose was reflected in the release, swelling and changes in the mass of the matrix tablets. In the medium with 0.05% sodium lauryl sulfate lower amount of drug released than in media without added surfactants was observed. Higher concentrations of sodium lauryl sulfate have improved the release of the drugs. The trend of swelling of tablets was in reverse correlation with the trend of the release of the drugs. A minor swelling and/or greater erosion of the tablet matrix at higher concentrations of sodium laurylsulfate was distinctive. The trend of mass change in most cases coincided with the trend of changing the size of the tablets - the more the tablet enlarged, the greater the mass. The swelling of tablets with sodium diclofenac in media with sodium lauryl sulfate was only to a lesser extent dependent on pH value of medium, solubility of the drug and solubilization of the drug, while these were important factors for the release rate of the poorly soluble drug. The effect of polysorbate 20 on the swelling of tablets without drug and tablets with paracetamol was not concentration dependent, the tablets swelled slightly more than in media without added surfactants, and it also had smaller effect on increasing the release of both drugs compared to sodium lauryl sulfate. In media with pH 5 polysorbate 20 slowed down the release of sodium diclofenac.