The dissolution behavior and pharmacokinetics of chlormadinone acetate (CMA) sustained-release tablets, a once daily drug for prostatic hypertrophy, were investigated.Chlormadinone acetate and enteric polymer (Eudragit S) were adsorbed on magnesium aluminometasilicate, and the admixtures were crushed to the size of 80-110 μm in diameterThe powder obtained was mixed with low-substituted hydroxypropyl cellulose, CM-cellulose calcium and magnesium stearate, and compressed into tablets.The tablets were coated with enteric polymer (Eudragit LD) (Test tablet D).The dissolution characteristics of CMA from Test tablet D and a com. tablet (Prostal L) were identical.The pharmacokinetics after a single oral administration of Test tablet D and the com. tablet were examined in healthy adult male volunteers.Test tablet D and the com. tablet were mutually bioequivalent.The influence of food on the bioavailability of these sustained-release tablets was observed; the extent of bioavailability of CMA after a meal was larger than that under fasting conditions.Judging from the simulated serum concentrations after multiple administration, Test tablet D is expected to be effective in a once-a-day dosing regimen as well as for immediate-release tablets in a twice-a-day dosing regimen.If a tablet exhibits the same in vitro dissolution profiles, it will exhibit the same in vivo pharmacokinetics.