Dr. Ron’s Research Review – March 21, 2012

This week’s research review focuses on oral vs. transdermal HRT.

Bypassing hepatic metabolism appears to result in more stable serum estradiol levels without supraphysiologic concentrations in the liver. By avoiding first-pass metabolism, transdermal hormone therapy may have less pronounced effects on hepatic protein synthesis, such as inflammatory markers, markers of coagulation and fibrinolysis, and steroid binding proteins, while oral hormone therapy has more pronounced hyper-coagulant effects and increases synthesis of C-reactive protein and fibrinolytic markers. Both oral and transdermal delivery systems have beneficial effects on high-density lipoprotein cholesterol to low-density lipoprotein cholesterol ratios (oral>transdermal), while the transdermal system has more favorable effects on triglycerides. Incidence of metabolic syndrome and weight gain appears to be slightly lower with a transdermal delivery system. Oral estrogen's significant increase in hepatic sex hormone binding globulin production lowers testosterone availability compared with transdermal delivery, with clinically relevant effects on sexual vigor. (Goodman 2012)

In 2003, the Estrogen and Thromboembolism Risk Study, a French case-control study, showed, for the first time, a differential association of oral and transdermal estrogens on the risk of venous thromboembolism. Contrary to oral estrogens, transdermal estrogens were not associated with an increased risk for venous thromboembolism. (Scarabin, Oger et al. 2003)

The final results of the Estrogen and Thromboembolism Risk (ESTHER) study and the E3N French cohort study confirmed the potential safety of transdermal estrogens with respect to thrombotic risk. (Canonico, Oger et al. 2007) (Canonico, Fournier et al. 2010)

Dr. Ron


Articles

Hormone therapy and venous thromboembolism among postmenopausal women: impact of the route of estrogen administration and progestogens: the ESTHER study

            (Canonico, Oger et al. 2007) Download

BACKGROUND: Oral estrogen therapy increases the risk of venous thromboembolism (VTE) in postmenopausal women. Transdermal estrogen may be safer. However, currently available data have limited the ability to investigate the wide variety of types of progestogen. METHODS AND RESULTS: We performed a multicenter case-control study of VTE among postmenopausal women 45 to 70 years of age between 1999 and 2005 in France. We recruited 271 consecutive cases with a first documented episode of idiopathic VTE (208 hospital cases, 63 outpatient cases) and 610 controls (426 hospital controls, 184 community controls) matched for center, age, and admission date. After adjustment for potential confounding factors, odds ratios (ORs) for VTE in current users of oral and transdermal estrogen compared with nonusers were 4.2 (95% CI, 1.5 to 11.6) and 0.9 (95% CI, 0.4 to 2.1), respectively. There was no significant association of VTE with micronized progesterone and pregnane derivatives (OR, 0.7; 95% CI, 0.3 to 1.9 and OR, 0.9; 95% CI, 0.4 to 2.3, respectively). In contrast, norpregnane derivatives were associated with a 4-fold-increased VTE risk (OR, 3.9; 95% CI, 1.5 to 10.0). CONCLUSIONS: Oral but not transdermal estrogen is associated with an increased VTE risk. In addition, our data suggest that norpregnane derivatives may be thrombogenic, whereas micronized progesterone and pregnane derivatives appear safe with respect to thrombotic risk. If confirmed, these findings could benefit women in the management of their menopausal symptoms with respect to the VTE risk associated with oral estrogen and use of progestogens.

Postmenopausal hormone therapy and risk of idiopathic venous thromboembolism: results from the E3N cohort study

            (Canonico, Fournier et al. 2010) Download

OBJECTIVE: Oral estrogen therapy increases venous thromboembolism risk among postmenopausal women. Although recent data showed transdermal estrogens may be safe with respect to thrombotic risk, the impact of the route of estrogen administration and concomitant progestogens is not fully established. METHODS AND RESULTS: We used data from the E3N French prospective cohort of women born between 1925 and 1950 and biennially followed by questionnaires from 1990. Study population consisted of 80 308 postmenopausal women (average follow-up: 10.1 years) including 549 documented idiopathic first venous thromboembolism. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox proportional models. Compared to never-users, past-users of hormone therapy had no increased thrombotic risk (HR=1.1; 95% CI: 0.8 to 1.5). Oral not transdermal estrogens were associated with increased thrombotic risk (HR=1.7; 95% CI: 1.1 to 2.8 and HR=1.1; 95% CI: 0.8 to 1.8; homogeneity: P=0.01). The thrombotic risk significantly differed by concomitant progestogens type (homogeneity: P<0.01): there was no significant association with progesterone, pregnanes, and nortestosterones (HR=0.9; 95% CI: 0.6 to 1.5, HR=1.3; 95% CI: 0.9 to 2.0 and HR=1.4; 95% CI: 0.7 to 2.4). However, norpregnanes were associated with increased thrombotic risk (HR=1.8; 95% CI: 1.2 to 2.7). CONCLUSIONS: In this large study, we found that route of estrogen administration and concomitant progestogens type are 2 important determinants of thrombotic risk among postmenopausal women using hormone therapy. Transdermal estrogens alone or combined with progesterone might be safe with respect to thrombotic risk.

Are All Estrogens Created Equal? A Review of Oral vs. Transdermal Therapy

            (Goodman 2012) Download

Abstract Background: To compare oral and transdermal delivery systems in domains of lipid effects; cardiovascular, inflammatory, and thrombotic effects; effect on insulin-like growth factor, insulin resistance, and metabolic syndrome; sexual effects; metabolic effects including weight; and effects on target organs bone, breast, and uterus. Methods: Review of the literature 1990-2010. Studies selected on basis of applicability, quality of data, and relationship to topic. Results: Data applicable to the comparisons of oral versus transdermal delivery systems for postmenopausal estrogen therapy were utilized to perform a review and formulate conclusions. Conclusions: Significant differences appear to exist between oral and transdermal estrogens in terms of hormonal bioavailability and metabolism, with implications for clinical efficacy, potential side effects, and risk profile of different hormone therapy options, but neither results nor study designs are uniform. Bypassing hepatic metabolism appears to result in more stable serum estradiol levels without supraphysiologic concentrations in the liver. By avoiding first-pass metabolism, transdermal hormone therapy may have less pronounced effects on hepatic protein synthesis, such as inflammatory markers, markers of coagulation and fibrinolysis, and steroid binding proteins, while oral hormone therapy has more pronounced hyper-coagulant effects and increases synthesis of C-reactive protein and fibrinolytic markers. Both oral and transdermal delivery systems have beneficial effects on high-density lipoprotein cholesterol to low-density lipoprotein cholesterol ratios (oral>transdermal), while the transdermal system has more favorable effects on triglycerides. Incidence of metabolic syndrome and weight gain appears to be slightly lower with a transdermal delivery system. Oral estrogen's significant increase in hepatic sex hormone binding globulin production lowers testosterone availability compared with transdermal delivery, with clinically relevant effects on sexual vigor.


Differential association of oral and transdermal oestrogen-replacement therapy with venous thromboembolism risk

            (Scarabin, Oger et al. 2003) Download

BACKGROUND: Oral oestrogen-replacement therapy (ERT) activates blood coagulation and increases the risk of venous thromboembolism (VTE) in postmenopausal women. Transdermal ERT has little effect on haemostasis, but data assessing its effect on thrombotic process are scarce. We aimed to examine the effect of the route of oestrogen administration on VTE risk. METHODS: We did a multicentre hospital-based case-control study of postmenopausal women in France. During 1999-2002, we recruited 155 consecutive cases with a first documented episode of idiopathic VTE (92 with pulmonary embolisms and 63 with deep venous thrombosis), and 381 controls matched for centre, age, and time of recruitment. FINDINGS: Overall, 32 (21%) cases and 27 (7%) controls were current users of oral ERT, whereas 30 (19%) cases and 93 (24%) controls were current users of transdermal ERT. After adjustment for potential confounding variables, the odds ratio for VTE in current users of oral and transdermal ERT compared with non-users was 3.5 (95% CI 1.8-6.8) and 0.9 (0.5-1.6), respectively. Estimated risk for VTE in current users of oral ERT compared with transdermal ERT users was 4.0 (1.9-8.3). INTERPRETATION: Oral but not transdermal ERT is associated with risk of VTE in postmenopausal women. These data suggest that transdermal ERT might be safer than oral ERT with respect to thrombotic risk.


References

Canonico, M., A. Fournier, et al. (2010). "Postmenopausal hormone therapy and risk of idiopathic venous thromboembolism: results from the E3N cohort study." Arterioscler Thromb Vasc Biol 30(2): 340-5.

Canonico, M., E. Oger, et al. (2007). "Hormone therapy and venous thromboembolism among postmenopausal women: impact of the route of estrogen administration and progestogens: the ESTHER study." Circulation 115(7): 840-5.

Goodman, M. P. (2012). "Are All Estrogens Created Equal? A Review of Oral vs. Transdermal Therapy." J Womens Health (Larchmt) 21(2): 161-9.

Scarabin, P. Y., E. Oger, et al. (2003). "Differential association of oral and transdermal oestrogen-replacement therapy with venous thromboembolism risk." Lancet 362(9382): 428-32.