Renal, biliary and intestinal clearance of sotalol enantiomers in rat model: evidence of intestinal exsorption.

Biliary clearance (Clb) of sotalol (STL) enantiomers was assessed in anaesthetized Sprague-Dawley rats (419 +/- 9 g, mean +/- SEM, n = 4) following administration of a 10 mg kg-1 i.v. dose of the racemate. Clb for S- and R-STL (0.0675 +/- 0.0090 and 0.0662 +/- 0.0089 mL min-1 kg-1, respectively) represented approximately 0.3% of systemic clearance (Cls) values for S- and R-STL (20.4 +/- 2.2 and 20.7 +/- 2.0 mL min-1 kg-1, respectively). Bile:plasma concentration ratios at 1, 2, and 3 h post-dose were approximately 1.4, 1.3, and 1.2 for both STL enantiomers. Renal clearance (Clr) and intestinal clearance (Cli) of STL enantiomers were assessed in conscious Sprague-Dawley rats (325 g, n = 4) following administration of a 10 mg kg-1 i.v. dose of the racemate. STL enantiomers were predominantly eliminated intact in the urine: Clr for S- and R-STL (26.3 +/- 3.2 and 28.7 +/- 4.2 mL min-1 kg-1 respectively) accounted for approximately 96% of Cls for S- and R-STL (27.5 +/- 3.3 and 29.9 +/- 4.2 mL min-1 kg-1, respectively). Approximately 4% of the dose was recovered in the faeces, corresponding to Cli values of 1.16 +/- 0.17 and 1.26 +/- 0.19 mL min-1 kg-1 for S- and R-STL, respectively. Total recovery of the administered dose in urine and faeces was 99.7 +/- 0.2 and 99.8 +/- 0.5% for S- and R-STL, respectively. It is concluded from these results in the rat model that (i) STL enantiomers are predominantly eliminated intact in urine; (ii) STL enantiomers are excreted intact in bile, and to a much larger extent in the faeces, thus suggesting the presence of intestinal exsorption of STL; (iii) STL does not appear to be metabolized; and (iv) Cls, Clr, Clb, and Cli are negligibly stereoselective.