Effect of Surfactant Type and Concentration on the Duration of Mucoadhesion of Carbopol 934 and HPMC Solid Compacts

In order to formulate an efficient and durable mucoadhesive drug delivery system, careful consideration of formulation-related parameters is critical. This study was conducted to investigate the effect of the presence of various types and concentrations of surfactants within or outside Carbopol 934 (C934) as well as hydroxypropylmethyl cellulose (HPMC) solid compacts, on their duration of mucoadhesion in vitro. Surfactants used in this study were chlorhexidine (CLH, cationic), sodium lauryl sulfate (SLS, anionic), and Poloxamer 407 (POL407, nonionic). These surfactants were individually dissolved in pH 7.0 phosphate buffer or added inside the solid compacts, and their effects on the duration of mucoadhesion of C934 and HPMC solid compacts determined at 37°C, using rat small intestine as the model membrane. Results showed that the presence of CLH outside both C934 and HPMC compacts produces the greatest reduction in their duration of mucoadhesion among the three types of surfactants studied. Effect of the other two investigated surfactants, on reducing the duration of mucoadhesion of C934 and HPMC solid compacts was exceedingly less than that of CLH. For C934 compacts, the effect of SLS was to some extent more than POL407. However, the reverse was observed with HPMC compacts. With all the different types of surfactants investigated, increasing the concentration of surfactant resulted in a greater reduction in the duration of mucoadhesion of solid compacts. Furthermore, HPMC compacts were generally found to be more sensitive to the presence of various types and concentrations of surfactants within the external buffer medium. In fact the presence of CLH at a concentration of 0.2%, within the buffer medium, completely prevented their adhesion to the mucosal surfaces. In conclusion, the presence of all three types of surfactants studied within C934 solid compacts reduced the duration of mucoadhesion greatly less than their presence within the buffer medium. This trend was also observed for HPMC compacts containing CLH and POL407. However, the presence of SLS (at concentrations above 0.5%) within HPMC compacts managed to reduce their duration of mucoadhesion more than when present in the outer buffer medium.