Comparison of brachial artery vascular responses among postmenopausal women receiving different doses of tibolone

Abstract Objective To compare the effects of low and conventional doses of tibolone in brachial artery flux parameters among postmenopausal women. Methods Between March 2011 and September 2012, 24 postmenopausal women attending Gynecology and Obstetrics Hospital Luis Castelazo Ayala, Mexico City, for hormone replacement therapy were consecutively recruited. The women were alternately assigned to receive a daily dose of either 2.5 mg (n = 11) or 1.25 mg (n = 13) of oral tibolone. Before and after treatment, all women underwent a brachial artery Doppler ultrasound. The arterial diameter was measured, and the pulsatility index (PI) and the resistance index (RI) were calculated. A hyperemic stimulus was then induced and these parameters were measured again. Results Among the 24 women, the time since menopause ranged from 16 to 24 months, and the median treatment duration was 3 months. Both groups showed a significant increase in arterial diameter after treatment. There was no significant difference between the groups in arterial diameter, PI, and RI. The arterial diameter after hyperemic stimulus was significantly lower after treatment than before treatment in both groups. Conclusion Low and conventional doses of tibolone induced similar changes in brachial artery flux parameters among postmenopausal women.