Formulation development and stabililty testing of extemporaneous suspension prepared from dapsone tablets

The qualification and quantification of dapsone in suspension were developed and shown to be stability indicating by means of a reverse-phase high-performance liquid chromatographic method. The real solubility of dapsone in water was calculated to be 0.208mg/mL at 25 deg C. The enthalpy of solution and the entropy of solution were calculated to be -175.6 J/g and -43605.7 J/K/M, respectively. An extemporaneous suspension was formulated from commercially available dapsone rablets, and the chemical stability of dapsone in the suspension was determined by means of accelerated stability testing. The 91-day analytical stabilty testing study was conducted at 4, 30, 50, 60, and 70 deg C. The energy of activation for the suspension was determined to be -23288.35 J/K/M. The zero-order rate of degradation for dapsone (k0,25) in suspension at 25 deg C was found to be 0.040845 day -1. The first-order rate of degradation for dapsone in solution was found to be 0.196370 (mg/mL)(day-1). The shelf life for the suspension was calulated to be 31.67 days at 25 deg C and 230.76 days under refrigeration at 4 deg C.