Action of several -adrenoceptor blocking drugs in the pregnant sheep and foetus.

1. The effect of several beta-adrenoceptor blocking drugs on the pregnant ewe and foetus were studied. Bunolol, butidrine, oxprenolol, propranolol and USVP65-24 all crossed the ovine placenta and produced a beta-adrenoceptor blockade in the ovine foetus. AH3474, AY21011 and sotalol did not cross the ovine placenta as assessed by the absence of a beta-blockade in the foetus when these compounds were administered to the pregnant ewe.2. Of the beta-blocking compounds tested, only propranolol and oxprenolol produced a prolonged blockade in the foetus. The beta-blockade with propranolol was of 3 h duration in the ewe and 10 h duration in the foetus. Oxprenolol produced a beta-blockade of 3 h duration in the ewe and 8 h in the foetus.3. The beta-blocking drugs which did cross the ovine placenta were more soluble in organic solvents (ether, chloroform, corn oil and olive oil) than those which did not cross the ovine placenta.