In: Respiratory3 Sep 2014
Our results in women with chronic respiratory failure provide evidence that a significant proportion of the improvement of gas exchange achieved with the 14-day MPA therapy is maintained beyond 3 weeks after cessation of the hormone therapy. This high-dose of MPA was also well tolerated by postmenopausal women. These results warrant further studies into the efficacy of MPA pulse therapy compared with continuous administration. As far as BP responses are concerned, our preliminary observations suggest that periodic MPA therapy might have some benefits over continuous administration.
The time course of the respiratory stimulation effect of MPA has previously been studied in healthy men. The initial effect of 60 mg MPA per day appears at 48 h and maximal stimulation is achieved in 7 days. After MPA therapy for 2 weeks, the ventilatory effects subside within 14 days. These findings are contradictory to ours, inasmuch as we found a marked residual respiratory stimulation even after 3 weeks of cessation of MPA. This could be explained by several factors. First, our subjects were not healthy but suffered from severe pulmonary disease with chronic or episodic respiratory failure. Click Here
The duration of the MPA effect has not directly been addressed in pulmonary patients, but some studies provide evidence for a prolonged effect of MPA. Delaunois et al administered MPA 75 mg/d to 15 men with stable COPD for 7 days and observed that in four subjects the PaC02 continued to decrease 1 week after cessation of MPA. They suggested that those subjects might have had temporary worsening of their condition during MPA with spontaneous improvement coinciding with the checkpoint at 1 week after cessation. This could not have been the case in our study, in which the condition of all patients remained stable and their spirometric values did not change during the study period. Lyons and Huang used IM progesterone in eight patients (two men and six women) with severe obesity hypoventilation and followed up the PaC02 in five of them after 18 to 30 days of hormone therapy. The therapeutic effect achieved with progesterone was maintained in three subjects (two men and one woman) for 1 to 4 months, before returning to chronic hypercapnia. We previously studied eight postmenopausal women who presented with nocturnal CO2 retention that was related to partial upper airway obstruction during sleep. Also in those women we were able to demonstrate sustained improvement of end-tidal CO2 during sleep, measured 3 weeks after cessation of MPA.
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