Medroxyprogesterone in postmenopausal females with partial upper airway obstruction during sleep.

The aim of the present study was to evaluate the degree and duration of respiratory stimulation caused by medroxyprogesterone acetate (MPA), and compare the effect of MPA to that of nasal continuous positive airway pressure (nCPAP) in sleep-disordered breathing. Ten postmenopausal females with predominantly partial upper airway obstruction during sleep had an overnight sleep study at baseline, on the fourteenth day of treatment with MPA and after a 3-week washout period. Six subjects on nCPAP were also studied 3 months later. At baseline, the overnight mean+/-SD end-tidal pressure of carbon dioxide (Pet,CO2) was 5.5+/-0.4 kPa the arterial oxygen saturation (Sa,O2) 93.0+/-1.2%, Sa,O2 nadir 80.0+/-6.7%, and frequency of oxygen desaturation > or = 4% (ODI4) per hour 2.2+/-1.3. MPA decreased Pet,CO2 by 0.8 kPa (14.5%, p<0.001). After washout, the mean Pet,CO2 remained at 0.5 kPa (9.1%, p<0.001) lower than at baseline. Sa,O2 did not change. Pet,CO2 was lower on MPA than on nCPAP (4.7+/-0.2 kPa versus 5.0+/-0.3 kPa; p=0.037) but Sa,O2 was similar. Apnoea/hypopnoea index tended to be lower on CPAP than on MPA. Medroxyprogesterone acetate at a daily dose of 60 mg improves ventilation in postmenopausal females with partial upper airway obstruction during sleep without compromising sleep. The ventilatory improvement is sustained for at least 3 weeks posttreatment. Medroxyprogesterone acetate was more efficient in decreasing the partial pressure of carbon dioxide but continuous positive airway pressure was superior in decreasing respiratory efforts.