Effect of Chlormadinone Acetate, a Synthetic Progesterone, on Hypoxic Ventilatory Response in Men

Abstract

Ten healthy young males were studied with a double-blind, cross-over trial to determine whether or not chlormadinone acetate (CMA), a potent synthetic progesterone, augments hypoxic chemosensi-tivity. Seven days after CMA administration, inspiratory minute volume (Vi) and tidal volume (FT) significantly increased. PaCo2 decreased by 3.0 ± 2.6 (S.D.) Torr (p<0.05) and plasma bicarbonate decreased by 2.9±1.1 mM (p<0.01). During CMA administration, the atmospheric hypoxic ventilatory response (HVR), assessed by minute ventilatory (ΔVt/ΔSaO2), and occlusion pressure responses (Δp2/ΔsaO2), significantly increased about 1.9 (p<0.05) and 1.6 times (p<0.01) compared to the placebo response, respectively. The calculated normocapnic HVR (ΔVt/ΔSaO2) increased about 2.3 times the placebo run. Hypoxic response evaluated by the withdrawal test, which represents the peripheral chemo-sensitivity without involving the influence due to secondary hypoxic depression, was about 1.7 times the placebo response (p<0.05). We conclude that CMA augments hypoxic respiratory chemosensitivity. © 1987, PHYSIOLOGICAL SOCIETY OF JAPAN. All rights reserved.