Effect of chlormadinone acetate, a synthetic progesterone, on restoring impaired load compensation in chronic obstructive pulmonary disease.

We examined whether or not progestational agents can improve the pathophysiological conditions by augmenting the respiratory drives in chronic obstructive pulmonary disease (COPD). At first, respiratory drives evaluated by ventilation and occlusion pressure responses to CO2 with and without inspiratory flow-resistive loading were compared between 19 COPD and 21 control subjects. Although there were no significant differences in occlusion pressure responses to CO2 between both groups, the load compensation assessed by the ratio of loaded to unloaded slopes in the occlusion pressure response to CO2 was significantly lower in the COPD patients than in the control subjects. Secondly, 14 COPD patients administered chlormadinone acetate (CMA), a synthetic progesterone, were examined, and it was found that the patients restored the impaired load compensation, particularly significant in the bronchitic type. Thirdly, the ratio of ventilation to occlusion pressure response to CO2 (delta VI/delta P.2) was significantly decreased in the emphysematous type, whereas such was not the case in the bronchitic type. Thus, improvement of load compensation in the bronchitic type was considered to have been accomplished without accompanying an impairment of ventilatory efficiency. We conclude that CMA could be used as a relevant respiratory stimulant.