Tibolone: A Unique Version of Hormone Replacement Therapy

Tibolone and Breast Cancer

Tibolone, a selective tissue estrogenic activity regulator, is a synthetic steroid with distinct pharmacological and clinical characteristics in contrast to conventional menopausal hormone therapy. Tibolone induces estrogenic activity in the brain, vagina, and bone but remains inactive in the endometrium and breast. In particular, several studies have investigated whether tibolone usage increases the risk of breast cancer. This study aims to determine the effects of tibolone on the breast by focusing on the relation between tibolone use and breast cancer. Our investigation emphasizes recent studies, particularly those based on Asian populations.

Menopausal hormone therapy and the risk of cataracts in postmenopausal women in South Korea

PURPOSE

Postmenopausal women have a higher prevalence of cataracts than men of a similar age. This study aimed to evaluate the effects of menopausal hormone therapy (MHT) on lens opacities in postmenopausal women.

METHODS

This retrospective cohort study analysed population-based health insurance data in South Korea collected from 2002 to 2019. To determine the risk factors associated with cataract, postmenopausal women (N = 2,506,271) were grouped according to post-MHT use. The treatment group was further divided into the following subgroups: tibolone, combined oestrogen plus progestin by manufacturer, oral oestrogen, combined oestrogen plus progestin by physician and topical oestrogen groups. The main outcome measure was the prevalence of cataracts.

RESULTS

The control group comprised 463,151 postmenopausal women who had never used MHT after menopause, while the treatment group included 228,033 postmenopausal women who had used MHT continuously for at least 6 months. The treatment group had a higher incidence of cataracts than the control group based on Cox proportional hazards ratio analysis. Low socioeconomic status and high parity were identified as risk factors for cataracts, and reduced risk of cataracts was associated with living in rural areas and drinking alcohol.

CONCLUSIONS

Women undergoing post-MHT, including tibolone, had a higher incidence of cataracts. Cataract development should be a concern when examining postmenopausal patients using MHT.

Tibolone as Hormonal Therapy and Neuroprotective Agent

Tibolone (TIB), a selective tissue estrogenic activity regulator (STEAR) in clinical use by postmenopausal women, activates hormonal receptors in a tissue-specific manner. Estrogenic activity is present mostly in the brain, vagina, and bone, while the inactive forms predominate in the endometrium and breast. Conflicting literature on TIB's actions has been observed. While it has benefits for vasomotor symptoms, bone demineralization, and sexual health, a higher relative risk of hormone-sensitive cancer has been reported. In the brain, TIB can improve mood and cognition, neuroinflammation, and reactive gliosis. This review aims to discuss the systemic effects of TIB on peri- and post-menopausal women and its role in the brain. We suggest that TIB is a hormonal therapy with promising neuroprotective properties.

Effects of Human Sulfotransferase 2A1 Genetic Polymorphisms 3 on the Sulfation of Tibolone

BACKGROUND AND OBJECTIVES

Previous studies have demonstrated the metabolism of tibolone through sulfation, with the cytosolic sulfotransferase (SULT) SULT2A1 as the major responsible enzyme. The current study aimed to investigate how SULT2A1 genetic polymorphisms may affect the dehydroepiandrosterone (DHEA)- and tibolone-sulfating activity of SULT2A1.

METHODS

Site-directed mutagenesis was employed to generate cDNAs encoding ten different SULT2A1 allozymes. Recombinant SULT2A1 allozymes were expressed in BL21 E. coli cells, and purified using glutathione-sepharose affinity chromatography. An established sulfotransferase assay was used to analyze DHEA- and tibolone-sulfating activity of the purified SULT2A1 allozymes.

RESULTS

The nine human SULT2A1 allozymes plus the wild-type SULT2A1 were found to display differential sulfating activity toward DHEA and tibolone. Kinetic analysis revealed that different SULT2A1 allozymes exhibited differential substrate affinity and catalytic efficiency toward the two substrates tested.

CONCLUSION

The results obtained provided useful information concerning the differential metabolism of tibolone through sulfation in individuals with different SULT2A1 genotypes.

Changes in serum calcium and vitamin D₃ levels after tibolone treatment and their correlations with health-related quality of life

OBJECTIVE

To assess the effects of tibolone on serum calcium and vitamin D3 levels, the effects on health-related quality of life (HRQOL), and the relationship between these variables.

METHODS

An open-label, prospective, parallel-arm study was conducted at S.C. Das Memorial Medical and Research Center, Kolkata, India, between July 2012, and June 2013. Women aged 34-55 years were eligible when they were experiencing surgical menopause and were symptomatic. Group A comprised patients who chose to receive tibolone (2.5mg daily for 6 months) and group B comprised those who refused treatment. At baseline and 6 months, body mass index (BMI), serum calcium and vitamin D3 levels and HRQOL were assessed.

RESULTS

Of 79 participants, 53 were in group A and 26 in group B. After 6 months, BMI had increased significantly in both groups. The vitamin D3 level had increased significantly from baseline in group A (P=0.02), and was higher than that in group B (P=0.01). HRQOL had also improved significantly from baseline in group A (P=0.001), and was significantly better than that in group B (P<0.001). In group A, a significant correlation was found between HRQOL improvement and vitamin D3 levels (P<0.001).

CONCLUSION

Tibolone significantly increases the serum vitamin D3 level and improves HRQOL in menopausal women. Clinical Trial Registry India: CTRI/2012/06/002752.

Tibolone protects T98G cells from glucose deprivation

The steroidal drug Tibolone is used for the treatment of climacteric symptoms and osteoporosis in post-menopausal women. Although Tibolone has been shown to exert neuroprotective actions after middle cerebral artery occlusion, its specific actions on glial cells have received very little attention. In the present study we have assessed whether Tibolone exerts protective actions in a human astrocyte cell model, the T98G cells, subjected to glucose deprivation. Our findings indicate that Tibolone decreases the effects of glucose deprivation on cell death, nuclear fragmentation, superoxide ion production, mitochondrial membrane potential, cytoplasmic calcium concentration and morphological parameters. These findings suggest that glial cells may participate in the neuroprotective actions of Tibolone in the brain.

Rationale for low-dose systemic hormone replacement therapy and review of estradiol 0.5 mg/NETA 0.1 mg

The menopausal transition is associated with several symptoms, for which both non-pharmacological and pharmacological measures are available to provide relief. However, present knowledge indicates that the former is not highly effective, and that the latter, in terms of systemic oestrogen and progestogen-based hormone replacement therapy (HRT), although being effective (e.g. on vasomotor symptoms, bleeding control, bone mineral density, vaginal atrophy and quality of life), can be associated with some caveats. Amongst these are an increased risk for coronary heart disease, breast cancer, venous thromboembolism and stroke. In recent years, literature has indicated a dose dependency for HRT on some of the caveats, hence authorities (Food and Drug Administration, and the European Medicines Agency) and menopause societies (International Menopause Society and North American Menopause Society) now recommend that women deemed in need of HRT should receive the lowest possible dose without compromising the effect of symptom relief. Estradiol 0.5 mg/norethisterone acetate (NETA) 0.1 mg, despite being a lower dose than conventional hormones, is a compound, among a few other low-dose options, that can be used in such therapy. As a first-line oral option, it has demonstrated its effectiveness (which seems comparable to other compounds), with high tolerability and, apparently, no safety concerns, in a 6-month study. Further long-term clinical trials and observational studies are mandatory in order to capture any potential harm as well as to elucidate this compound's full potential. Following a thorough literature search using PubMed and MEDLINE from the earliest publication dates through to January 2008, including results from various types of clinical trials and statements on HRT, we review the rationale for these recommendations. We also review the effects and safety of a novel 'ultra-low-dose' oral continuous combined HRT tablet, estradiol 0.5 mg/NETA 0.1 mg.

Different effects of tibolone and low-dose EPT in the management of postmenopausal women with primary headaches

OBJECTIVE

The present randomized prospective study aimed to compare the effect of tibolone (T) with conventional low-dose estrogen-progestogen therapy (EPT) administered in a combined continuous regimen on the course of primary headaches in postmenopausal women requesting hormone therapy (HT) for climacteric complaints.

DESIGN

Forty women presenting for clinical evaluation of headache (migraine without aura and episodic tension-type headache) were enrolled. The observational period lasted 7 months during which women kept a diary of the clinical characteristics of headache attacks and analgesic use. Climacteric symptoms and both anxiety and depression were also measured. After a 1-month run-in period, women received two different HT regimens: 1 mg 17beta-estradiol + 0.5 mg norethisterone acetate (EPT) or 2.5 mg T. Follow-up evaluations were planned after 3 and 6 months of treatment.

RESULTS

Although T did not affect the number of days with migraine without aura, it significantly reduced the number of hours during which pain intensity prohibited daily activities (P < 0.001) and the number of analgesics (P < 0.001) after 3 months. Conventional low-dose EPT administered in a combined continuous regimen was confirmed to have a mild, but negative, effect on the course of migraine without aura by increasing the number of days with head pain (P < 0.001) and the number of analgesics (P < 0.001). Interestingly, both treatments were effective in the management of episodic tension-type headache, significantly reducing the number of days with head pain, severity, and analgesic consumption.

CONCLUSIONS

In postmenopausal headache sufferers, analgesics are more effective in alleviating severe head pain when women are treated with T in comparison with low-dose EPT for climacteric complaints.

Biological options to enhance periprosthetic bone mass

There is a potential for the use of pharmacological agents to enhance the quality of bone around a total hip or knee prosthesis, reducing the risk of implant failure or periprosthetic fracture. Bisphosphonates are currently used for the management of postmenopausal osteoporosis and recent investigations also suggest a potential role for the management of postoperative periprosthetic bone loss. Current evidence suggests that the short-term gains may not be sustained in the long term. Teriparatide and parathyroid hormone 1-84 have been licensed to treat postmenopausal osteoporosis and may also be investigated for the potential to enhance periprosthetic bone mass. In addition, other agents such as calcitonin and strontium ranelate, non-anabolic agents such as doxycycline, and recombinant OPG adeno-associated virus (rAAV) gene therapy, may in the future provide solutions for enhancing periprosthetic bone mass.

Vasomotor symptoms in menopause: physiologic condition and central nervous system approaches to treatment

OBJECTIVE

The decline in concentrations of gonadal hormones during menopause gives rise to a range of physiologic and psychologic changes that may impact a woman's health and quality of life significantly. Most notable among these are vasomotor symptoms (hot flashes and night sweats) and mood and sleep disturbances.

STUDY DESIGN

This article reviews the physiologic condition underlying menopausal vasomotor symptoms and centrally active, nonhormonal therapies that have demonstrated efficacy for their treatment.

RESULTS

Despite the emergence of a range of nonhormonal treatments for vasomotor symptoms, a need still exists for safe and effective therapeutic options that directly target the underlying thermoregulatory mechanisms for women who want treatment but prefer to avoid hormone therapy or for whom hormone therapy is contraindicated.

CONCLUSION

The availability of centrally active therapies for menopausal vasomotor symptoms with risks and benefits clearly defined by results from well-designed clinical trials has the potential to allay safety concerns that are associated with the treatment of these common symptoms.

Breast cancer and sex steroids: critical review of epidemiological, experimental and clinical investigations on etiopathogenesis, chemoprevention and endocrine treatment of breast cancer

There is strong epidemiological, experimental and clinical evidence that the etiology of breast cancer is closely related to long-term exposure of breast epithelium to sex steroid hormones. Estrogens can enhance the development of breast cancer by stimulating cell proliferation rate and thereby increasing the number of errors occurring during DNA replication, as well as by causing DNA damage via their genotoxic metabolites produced during oxidation reactions. Anti-estrogenic drugs, including tamoxifen, raloxifene and anastrozole, have been tested with promising results in the chemoprevention of breast cancer in high-risk women. As for the use of exogenous sex-steroids in the gynecological practice, data about breast cancer risk associated with oral contraception are reassuring, and available data on oral hormone replacement therapy (HRT) use for not more than 5 years have failed to detect a significant increase in the risk of developing a breast cancer. Long-term HRT administration increases the incidence of this tumor slightly, with a relative risk ranging from 1 to 2 depending on hormone preparation. Estrogens alone, even if taken for long periods of time, seem to be safer than estrogen/progestin combinations. New administration routes and novel hormone regimens are currently under evaluation, and these new HRT modalities could have different impact on breast cancer risk because of their metabolic and pharmacodynamic effects.