Pindolol drug elimination

Cimetidine not only reduces the metabolism of beta-blockers such as propranolol, it is also known to act as an inhibitor of tubular secretion of a number of organic cations. Therefore it is not surprising to see that the renal clearance of pindolol is substantially and stereoselectively reduced by coadministration of this drug [59]. The administration of 400 mg cimetidine twice a day for 2 days before and 2 days after pindolol administration resulted in 26% and 34% reductions in the renal clearances of S(—)- and R(-t-)-pindolol, respectively. Therefore the plasma concentrations of the R(-l-) enantiomer increased more drastically (47%) than those of the S(—) enantiomer (38%) in the presence of cimetidine [59]. Because renal clearance accounts for only 50% of pindolol elimination, the significant increases in the plasma concentrations of pindolol enantiomers as a result of cimetidine coadministration cannot be explained from the inhibition of its renal clearance only. Apparently, cimetidine also reduces the metabolism of pindolol. 

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