Effect of tibolone compared with sequential hormone replacement therapy on carbohydrate metabolism in postmenopausal women

Effects of tibolone or continuous combined oestradiol/norethisterone acetate on glucose and insulin metabolism

OBJECTIVE

To determine the effects of tibolone or oestradiol (E(2) )/norethisterone acetate (NETA) hormone replacement therapy on glucose and insulin metabolism in postmenopausal women.

DESIGN

Single-centre double-blind placebo-controlled randomized clinical trial.

SUBJECTS/METHODS

We randomized 105 healthy postmenopausal women to tibolone 2·5 mg daily, continuous combined oral E(2) 2 mg/NETA 1 mg daily or placebo over a 2-year study. We performed intravenous glucose tolerance tests (IVGTT) with measurements of plasma glucose, insulin and C-peptide concentrations and the IVGTT glucose elimination rate, k. Mathematical modelling was performed to determine measures of insulin sensitivity, S(i) , pancreatic insulin secretion and hepatic and plasma insulin elimination.

RESULTS

Tibolone decreased S(i) to 53-63% and k to 72-79% of baseline values but increased IVGTT phase 2 C-peptide concentrations 1·6-1·8-fold and pancreatic insulin secretion 2·2-2·4-fold, so overall IVGTT glucose concentrations were unaffected. Similar, but for k, significantly smaller changes in insulin and C-peptide secretion were seen with E(2) /NETA, also with no effect on overall IVGTT glucose concentrations.

CONCLUSIONS

Tibolone reduces insulin sensitivity. Healthy postmenopausal women seem able to compensate for this and maintain normal postload glucose concentrations, but it may not be advisable to prescribe tibolone to women with, or at increased risk for, diabetes.

Safety and efficacy of tibolone and menopausal transition: a randomized, double-blind placebo-controlled trial

OBJECTIVE

To evaluate the efficacy, safety and tolerability of Tibolone use during the menopausal transition (MT).

METHODS

Sixty-five healthy women aged 40-55 years (48.5 ± 3.5 years) were recruited for a randomized, double-blind controlled trial. Thirty participants were recruited to receive oral Tibolone 2.5 mg/day - Tibolone Group (TG), and 35 participants were assigned to the Placebo Group (PG), which received one capsule of lactose/day. Both groups were treated for 12 consecutive weeks. The Blatt-Kupperman Menopausal Index (KMI) and the Greene Climacteric Scale (GCS) were used. The glycaemic and lipid profiles, biochemical measures of hepatic function and endometrial thickness were measured for safety. A daily registry of complaints related to the treatment was maintained, and anthropometric measures were obtained to assess tolerability.

RESULTS

A total of 57 women completed the study. After 12 weeks of Tibolone use, the total score and percentage of the KMI and GCS were significantly decreased compared to baseline, which reflected the efficacy of the treatment of climacteric symptoms. The improvement in blood biochemistry, endometrial atrophy and maintenance of the anthropometrical measures reflected the safety of Tibolone use. The absence of serious side effects demonstrated good tolerability for Tibolone use.

CONCLUSIONS

The results showed good efficacy, tolerability and safety of Tibolone use during the MT.

Effects of menopause and tibolone on different cardiovascular biomarkers in healthy women

BACKGROUND AND AIM

The effects of tibolone on cardiovascular risk is not yet fully understood today. We designed this study to assess the effect of the menopausal status and tibolone treatment (2.5 mg/day for 3 months) on different biomarkers of cardiovascular risk in healthy women.

METHODS

Blood arterial pressure were measured, and blood samples collected for glucose, lipid profile (total cholesterol, high density lipoproteins, HDL, low density lipoproteins, and triglycerides), inflammatory (C-reactive protein, Interleukin-6, IL-6, tumor necrosis factor alpha, TNF alpha) and oxidative stress (hydroperoxides and antioxidant capacity) evaluation in 15 premenopausal (mean age: 30 +/- 4 years) and 15 postmenopausal (mean age: 52 +/- 3, mean time from menopause 1.4 +/- 0.4 years) women before and after tibolone treatment.

RESULTS

The menopausal status is associated with increased systolic and diastolic pressure (p<0.05), higher IL-6 (p<0.05) and TNF alpha (p<0.01), and lower antioxidants (p<0.01). However, blood pressure (p<0.05), glucose (p<0.05), TNF alpha (p<0.05) and HDL (p<0.05) fell after tibolone, which did not significantly affect levels of the other biochemical parameters.

CONCLUSIONS

As menopause is associated with increased blood pressure, inflammation and oxidative stress, tibolone restores blood pressure and has beneficial effect on inflammation and glycemia without worsening oxidative stress, although it also reduces HDL levels. Such modifications should be taken into account when tailoring menopausal therapies to specific requirements of each woman.

Effect of different preparations of hormone therapy on lipid and glucose metabolism, coagulation factors, and bone mineral density in overweight and obese postmenopausal women

OBJECTIVE

To determine the effects of different preparations of hormone therapy (HT) on lipid and glucose metabolism, coagulation factors, and bone mineral density (BMD) in overweight and obese postmenopausal women.

DESIGN

A randomized, nonblinded, controlled study.

SETTING

Karadeniz Technical University, Department of Obstetrics and Gynecology.

PATIENT(S)

A total of 352 overweight and obese (body mass index >25 kg/m2) postmenopausal women.

INTERVENTION(S)

Ninety women received 2.5 mg of tibolone; 84 received 2 mg of E2 plus 1 mg of norethisterone acetate (E2/NETA); 90 received 0.625 mg of conjugated equine estrogen plus 2.5 mg of medroxyprogesterone acetate (CEE/MPA); and 88 did not receive any menopausal therapy (control).

MAIN OUTCOME MEASURE(S)

At baseline and after 6 months of treatment, we measured total cholesterol, triglyceride, high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), insulin, glucose, factor VII, factor VIII, von Willebrand factor, antithrombin III, protein S, protein C, fibrinogen, and BMD at the lumbar spine L1-L4.

RESULT(S)

There were no statistically significant differences among the groups for any variables at baseline. After 6 months of treatment, the three regimens decreased total cholesterol, triglyceride, LDL, and fibrinogen; E2/NETA and CEE/MPA increased HDL, and tibolone decreased HDL; higher insulin concentrations were found in the control and tibolone groups. Body mass index, HDL, fibrinogen levels, and L1-L4 BMD were independent factors in the prediction of HT use.

CONCLUSION(S)

Body mass index, HDL, fibrinogen levels and L1-L4 BMD were independent factors in the prediction of HT use. Treatment with tibolone, E2/NETA, and CEE/MPA resulted in minimal improvement in lumbar spine BMD but had a beneficial effect on the procoagulation system, with minimal changes in glucose metabolism after 6 months of therapy.

Conjugated estrogen/progestagen versus tibolone hormone replacement therapy in postmenopausal women: Effects on carbohydrate metabolism and serum sex hormone-binding globulin

OBJECTIVE

To study the effects of different types of continuous hormone replacement therapy on carbohydrate metabolism.

METHOD

Postmenopausal women were treated with conjugated estrogens, 0.625 mg/medroxyprogesterone acetate, 2.5 or 5 mg (CEE/MPA) or tibolone 2.5 mg daily for 13 28-day cycles. Serum glucose and insulin were measured before and during a 75 g oral glucose tolerance test (OGTT) at baseline and after 3, 6 and 13 cycles and areas under the curve (AUC) were calculated. Sex hormone-binding globulin (SHBG) was measured as an additional marker of nutritional and insulin status.

RESULTS

Neither CEE/MPA 2.5mg nor tibolone had any effects on carbohydrate metabolism while AUC(insulin), AUC(glucose) and also body mass index (BMI) increased after 13 cycles of treatment in the CEE/MPA 5 mg group. SHBG increased significantly during CEE/MPA treatment and decreased significantly during treatment with tibolone. The effects on SHBG were less pronounced in the CEE/MPA 5mg group. Pretreatment SHBG showed significant negative correlations to BMI and to variables that may reflect a certain degree of insulin resistance, the most pronounced being fasting glucose. Changes in SHBG during treatment with tibolone were negatively correlated to pretreatment SHBG and positively to BMI, AUC(insulin) and fasting insulin resistance index, while no such correlations were found in the CEE/MPA groups. There were no correlations between changes in AUC(insulin) and AUC(glucose) on one hand and basal variables or treatment SHBG on the other in the CEE/MPA groups.

CONCLUSION

The effects of tibolone and CEE/MPA on carbohydrate metabolism were considered to have clinical significance only for CEE/MPA 5mg, indicating a less favourable role of the higher progestagen dose. The results further support the important role of metabolic and insulin status in the physiological regulation of SHBG and also indicate that the suppressive effect of tibolone on circulating SHBG is mainly depends on pretreatment SHBG levels. SHBG does not reflect changes in carbohydrate metabolism during CEE/MPA treatment.

Serum androgen levels and insulin resistance in postmenopausal women: association with hormone therapy, tibolone and raloxifene

OBJECTIVE

To assess endogenous androgen and insulin resistance status in postmenopausal women receiving continuous combined hormone therapy (HT), tibolone, raloxifene or no therapy.

METHODS

A total of 427 postmenopausal women aged 42-71 years were studied in a cross-sectional design. Among them 84 were taking HT (46 women conjugated equine estrogens 0.625 mg; medroxyprogesterone acetate, 5 mg, CEE/MPA; and 38 women 17beta-estradiol 2 mg; norethisterone acetate 1 mg, E2/NETA); 83 were taking tibolone 2.5 mg; 50 were taking raloxifene HCl 60 mg; and 210 women were not receiving any therapy. Main outcome measures were FSH, LH, estradiol, total testosterone, SHBG, free androgen index (FAI), Delta4-Androstendione (Delta4-A), Dehydroepiandrosterone sulphate (DHEAS) and HOMA insulin resistance index (HOMA-IR).

RESULTS

In women not on hormone therapy smoking and older age was associated with lower DHEAS levels. FAI values increased linearly with increasing BMI. Age and BMI were positive determinants of HOMA-IR, while no association was identified between endogenous sex steroids and insulin resistance. CEE/MPA therapy was associated with higher SHBG, lower FAI and lower HOMA-IR values compared to women not on therapy (age and BMI-adjusted SHBG: CEE/MPA 148.8 nmol/l, controls 58.7 nmol/l, p < 0.01; age-adjusted FAI: CEE/MPA 0.8, controls 3.2, p < 0.05; age-adjusted HOMA-IR: CEE/MPA 1.3, controls 2.6, p < 0.05). On the contrary, E2/NETA treatment had no effect on these parameters. Women on tibolone had lower SHBG, higher FAI and similar HOMA-IR values compared to controls (age and BMI-adjusted SHBG: 24.1 nmol/l, p < 0.01; FAI: 6.0, p < 0.05; HOMA-IR: 2.3, p = NS). Raloxifene users did not exhibit any difference with respect to sex steroids and HOMA-IR levels.

CONCLUSIONS

CEE/MPA users had lower free testosterone and improved insulin sensitivity. Tibolone on the other hand associated with higher free testosterone, while raloxifene did not relate to any of these parameters.

Administration of tibolone decreases 24h heart rate but not blood pressure of post-menopausal women

OBJECTIVE

Elevation of blood pressure and heart rate increase the risk of cardiovascular disease. Administration of estrogens does not affect heart rate but may decrease 24 h blood pressure. In this study, we tested the effect of the estro-progestogenic compound tibolone.

METHODS

Thirty healthy, post-menopausal women were randomized to receive placebo (n = 15) or tibolone, at the commonly prescribed dose of 2.5 mg per day (n = 15). Before and after 6 months of treatment, in each woman blood pressure and heart rate were monitored every 30 min for 41 h by an ambulatory device. Valuable readings were those collected from 8:00 a.m. of the second day to 8:00 a.m. of third day. Analyses were performed of 24 h, day-time (7:00 a.m.-11:00 p.m.) and night-time (11:00 p.m.-7:00 a.m.) values. Day to night difference was also calculated.

RESULTS

Placebo did not modify 24h, day-time, and night-time blood pressure or heart rate values. Day-night differences were also not affected by placebo. Similarly to placebo, tibolone administration did not modify any of the blood pressure parameters taken into consideration. By contrast, a significant decline of 24 h heart rate (73.2 +/- 2.3 beats/min versus 69.3 +/- 1.7 beats/min; P < 0.0008) was observed. The effect was significant both at day (76.6 +/- 2.4 beats/min versus 72.1 +/- 1.9 beats/min; P < 0.0001) and night (65.8 +/ 2.6 beats/min versus 62.4 +/- 1.9 beats/min; P < 0.05). Day-night blood pressure and heart rate differences were not affected by tibolone.

CONCLUSIONS

In post-menopausal women, administration of tibolone does not influence 24 h blood pressure but reduces heart rate.

Effects of low and high dose oestradiol and dydrogesterone therapy on insulin and lipoprotein metabolism in healthy postmenopausal women

OBJECTIVE

Menopause diminishes insulin secretion and elimination, increases risk of diabetes and adversely affects lipoprotein metabolism. This study was undertaken to establish whether oral oestradiol plus dydrogesterone postmenopausal hormone therapy can modify these changes.

DESIGN

Randomized prospective trial of postmenopausal women taking low dose therapy (1 mg/day oestradiol-17 beta with 5 or 10 mg/day dydrogesterone for days 17-28 of each cycle, n = 15) or high dose therapy (2 mg/day oestradiol-17 beta with 10 or 20 mg/day orally administered dydrogesterone, n = 9).

MEASUREMENTS

Patients underwent measurement of glucose, insulin and C-peptide in the fasting state and during an intravenous glucose tolerance test (IVGTT) at baseline and after 12 and 24 cycles of treatment. Modelling analysis was used to derive measures of insulin secretion, elimination and sensitivity. Fasting serum lipids, lipoproteins and apolipoproteins were also measured.

RESULTS

In both groups there were significant reductions in fasting glucose, insulin and C-peptide. Pancreatic insulin secretion during the IVGTT was increased by treatment (ranging from 45% to 92%, P < 0.01). Insulin elimination was increased at both the peripheral (16% to 43%, P < 0.05) and hepatic (18% to 31%, P < 0.05) levels. Insulin sensitivity was unaffected. Low density lipoprotein (LDL) cholesterol was reduced and high density lipoprotein (HDL) cholesterol increased with treatment.

CONCLUSIONS

Postmenopausal hormone therapy with oestradiol plus dydrogesterone can favourably affect lipoprotein concentrations and can reverse menopause-associated changes in insulin secretion and elimination.

Effects of tibolone and conjugated equine estrogens with or without medroxyprogesterone acetate on body composition and fasting carbohydrate measures in surgically postmenopausal monkeys

The effects of tibolone on body weight, body composition, and fasting carbohydrate measures in surgically postmenopausal cynomolgus monkeys were compared to those of conjugated equine estrogens (CEE) with and without medroxyprogesterone acetate (MPA). Monkeys were fed a moderately atherogenic diet with either no hormones (control n = 29), CEE (0.042 mg/kg, n = 27), CEE + MPA (0.167 mg/kg, n = 29), low-dose tibolone (LoTib, 0.05 mg/kg, n = 30), or high-dose tibolone (HiTib, 0.20 mg/kg, n = 31) daily for 2 years. Body weight (BW) was measured throughout the study, and dual-energy x-ray absorptiometry (DEXA) scans of the abdominal region (lumbar vertebrae 1 through 5) were performed at the end of the trial to assess abdominal body composition. Fasting carbohydrate measures (glucose, insulin, C-peptide, and fructosamine) were determined at baseline and after 2 years of treatment. Compared to controls, BW significantly increased and abdominal soft tissue mass was greater (analysis of variance [ANOVA], P <.001, P = 0.003, respectively) in all but the CEE-treated group (P =.78, P =.94, respectively). HiTib-treated monkeys had greater abdominal lean mass compared to controls (P =.008), while there was no significant treatment effect on abdominal fat mass (analysis of covariance [ANCOVA], P =.29). Fasting insulin concentrations and fasting insulin/glucose ratios were greater in CEE + MPA- (P =.002, P =.03, respectively) and HiTib-treated monkeys (P =.03, P =.02, respectively) compared to controls. There was a strong trend for a treatment effect on fasting blood glucose concentration (ANCOVA, P =.06) with CEE + MPA-treated animals having the greatest values, despite no difference in fructosamine concentration (ANCOVA, P =.57). Using these fasting measures, the homeostasis model assessment (HOMA-IR) revealed significant insulin resistance with CEE + MPA treatment compared to controls (P =.008), while the quantitative insulin sensitivity check index (QUICKI) showed significantly impaired insulin sensitivity in all hormone replacement therapy (HRT) groups (all P values <.03), except CEE (P =.12). In conclusion, HRT with CEE + MPA or tibolone results in greater BW, abdominal soft tissue, and insulin resistance (CEE + MPA and HiTib) compared to control-treated monkeys.