Evaluation of tibolone effect on arterial resistance in postmenopausal women

The aim of this study was to evaluate the effect of tibolone on peripheral vascular resistance in postmenopausal women, by determination of the pulsatility index (PI) of the common carotid, radial and popliteal arteries using Doppler ultrasonography.

Twenty-nine patients were studied in a longitudinal, prospective, before and after study, for 7 months. The patients did not suffer from cardiovascular disease or any other conditions that would interfere with vascular resistance, and had no contraindications for hormone replacement therapy (HRT). Tibolone was used in a dose of 2.5 mg, orally, continuously for 6 months. Color duplex Doppler ultrasonography of the right and left common carotid, radial and popliteal arteries was carried out to determine PI, using the average value found in both sides at baseline (before administration of the drug), 3 and 6 months after initiating medication and 1 month after discontinuation of the drug. PI was determined by means of spectral analysis of the best arterial blood flow waveform, and pretreatment values (baseline) were used as control.

In the common carotid artery, no significant differences in PI were observed at 3 and 6 months, in comparison with baseline. A significant decrease in PI was noted in the radial artery at 6 months as compared with baseline (decrease of 51.5%). PI in the popliteal artery also presented a significant decrease at 6 months in relation to baseline (decrease of 28.6%). The results were statistically assessed by ANOVA (analysis of variance).

There was no significant variance in PI in the common carotid artery; however, in the radial and popliteal arteries there was significant variance, and their resistance decreased after use of tibolone for 6 months but returned to the pretreatment values 1 month after discontinuation of the drug.