The pharmacokinetics of nelfinavir tablets (A) and an oral simplified nelfinavir suspension (B) were studied. Twelve healthy volunteers randomly received either five 250-mg nelfinavir tablets or a simplified oral suspension obtained from tablets dissolved in water (nelfinavir 1250 mg in 100 mL of water) in a single dose before being crossed over to the second treatment after a one-week washout period. Blood samples were drawn up to 24 h after drug administration. Nelfinavir concentrations in plasma were analyzed by a specific and validated reverse-phase high-performance liquid chromatography assay (HPLC) with UV detection, and pharmacokinetic values were determined. For the AUC(0-infinity) with means+/-SD of 31.71+/-7.85, 30.88+/-10.28 (microg/L) respectively for treatments B and A, the ratio (F(B/A)) was of 1.1 with a C.I. of 0.90-1.24. For Cmax with means+/-SD of 3.1+/-0.6 (treatment B) and 3.2+/-0.8 mg/mL (treatment A), the ratio was 1.0. with C.I. of 0.92-1.08. The two treatments evidenced no significant differences in AUC(0-inifnity) and Cmax values and the two-one sided t-test showed that the two preparations are bioequivalent. There was no significant difference in Tmax between the liquid and tablets. Nelfinavir suspension might be a option for treating HIV-infected patients with swallowing disturbances or compliance problems.