Venous endothelial function in postmenopausal women after six months of tibolone therapy

Abstract

Study Objective: To test venous endothelial function in long-term climateric therapy with tibolone. Design: Measurement of dorsal hand-vein diameter by venous occlusion plethysmography during infusion of norepinephrine (NE), bradykinin (BK), NG-monomethyl l-arginine ( l-NMMA) and sodium nitroprusside (SNP). Setting: Plethysmography and Menopause Units. University Hospital Valdecilla. Santander. Spain. Patients: Eleven postmenopausal women having continuous treatment with oral tibolone (2.5 mg/day) for 6 months. Interventions: Three plethysmography studies were made: at baseline, and at three and six months of treatment. Main outcome measures: Dorsal hand-vein diameter measured by venous occlusion plethysmography during infusion of NE, BK, l-NMMA and SNP. Results: (a) Baseline study: maximum dilation with BK was 54.2±10.2%. (b) Three-month study: BK dilation of 71.5±11.9%, with a significant increase of 17.3% ( P=0.019) compared with baseline. (c) Six-month study: BK dilation of 77.5±11.9%, with a significant increase 23.3% ( P=0.002) compared with baseline. Maximal vasodilation was reached with SNP in the three studies and l-NMMA infusion has a similar vasoconstrictor response in the three studies. Conclusions: Long-term climateric therapy with tibolone improves vein endothelium-dependent vasodilation suggesting a positive impact of this drug on endothelial function.