Pharmacokinetics of pentoxifylline after oral administration of a sustained release tablet at two different times of the day

The pharmacokinetics of pentoxifylline (CAS-6493-05-6) was studied in healthy subjects by orally administering a 400 mg sustained release tablet (Trental(R)) at two different times (10:00 or 22:00 h) of the day in a crossover design. Pentoxifylline concentrations in serum samples were estimated by using high performance liquid chromatography. The mean values of C-max (326.38 +/- 39.77 vs 266.35 +/- 36.0 ng/ml, p < 0.01, n = 8), AUC(0-t) (2424 +/- 382 vs 2141 +/- 300 ng/ml/h, p < 0.05, n = 8) were significantly higher and V-ss/f (16537 +/- 2869 vs 20136 +/- 5006 ml/kg), v(d)/f (11807 +/- 2704 vs 15801 +/- 5960 ml/kg) were significantly (p < 0.05, n = 8) lower following morning (10:00 h) administration than in the night (22:00 h). These variations should be considered while designing sustained release dosage forms.