Abstract

Mefenamic acid is characterized by a low oral bioavailability due to its slow dissolution and absorption. The purpose of this study was to investigate the effect of salt formation on dissolution of mefenamic acid and its physical stability. Potassium, sodium and lysine salts of mefenamic acid were prepared. The resulting salts formed were characterized by scanning electron microscopy, hot-stage microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry and powder X-ray diffractometry. In addition, the accelerated stability test was performed at 45°±2° and 75 %±5 % relative humidity for 3 mo. The dissolution of prepared salts was evaluated in comparison to untreated mefenamic acid. The results showed that the potassium and sodium salts of mefenamic acid were successfully prepared, while lysine salt of mefenamic acid could not be formed by the same method. The dissolution of both potassium and sodium salts of mefenamic acid was not significantly different, but the sodium salt was more stable than potassium salt. For this reason, sodium mefenamate was selected for formulating immediate-release tablets. It was also found that the formulated tablets containing sodium mefenamate gave rapid drug dissolution, compared to untreated mefenamic acid. Thus, it can be concluded that the formation of sodium mefenamate and its tablet formulation improve the dissolution of mefenamic acid.