Pindolol: disposition and metabolism in rhesus monkeys after chronic treatment

1. The absorption, distribution, excretion and metabolism of pindolol were studied in rhesus monkeys after a single oral dose of 2.5 mg/kg or 25 mg/kg and after a chronic treatment of 5 years at the same daily dosage. 2. The pharmacokinetic parameters were the same for animals which received pindolol for the first time, and animals which underwent the 5 years' chronic treatment. An elimination half-life of 1.5 to 1.9 h was estimated in plasma for unchanged pindolol. 3. The distribution pattern of unchanged pindolol determined fluorimetrically, as well as total 14C in the tissues, following administration of [14C]pindolol showed no difference between a single dose and 5 years of chronic treatment. No accumulation of pindolol or metabolites was detected in the tissues of chronically treated animals. A mean elimination half-life of 10h was evaluated in 21 organs. 4. Acutely dosed and chronically treated rhesus monkeys showed the same metabolic pattern in urine. There was no evidence for induction or inhibition of the metabolism of pindolol.