Objective: To evaluate the absorption, placental transfer, receptor occupancy, and acute hemodynamic effects of a single peroral dose of pindolol in healthy term pregnancy. Methods: Ten pregnant healthy women admitted for cesarean section at term after uneventful pregnancy received each 5 mg of pindolol perorally before operation. The acute hemodynamic responses were measured, and maternal and fetal circulations were assessed with color Doppler ultrasonography. Pindolol concentrations were measured with a sensitive radioreceptor binding assay, and the corresponding beta2-receptor occupancy was determined. Results: Mean maternal concentration of pindolol 1 h after ingestion was 9.4 ng/ml, and it rose to 14.6 ng/ml at the time of cesarean section; respective beta2-receptor occupancies were 91.8% and 98.8%. In the umbilical artery, pindolol concentration was 50% of the maternal concentration. A plasma concentration of 2.5 ng/ml yielded 90% beta2-receptor occupancy, which reflects the high potency of pindolol. Conclusion: Despite almost total blockade of beta2-receptors, no changes in maternal-or fetal hemodynamics or Doppler flow velocity waveforms were observed.
