General Addition of a progestin when a woman has not had a hysterectomy Studies of the addition of a progestin for 10 or more days of a cycle of estrogen administration, or daily with estrogen in a continuous regimen, have reported a lowered incidence of endometrial hyperplasia than would be induced by estrogen treatment alone. Endometrial hyperplasia may be a precursor to endometrial cancer. There are, however, possible risks that may be associated with the use of progestins with estrogens compared to estrogen-alone regimens. These include a possible increased risk of breast cancer, adverse effects on lipoprotein metabolism (e.g., lowering HDL, raising LDL), and impairment of glucose tolerance. Elevated blood pressure In a small number of case reports, substantial increases in blood pressure have been attributed to idiosyncratic reactions to estrogens. In a large, randomized, placebo-controlled clinical trial, a generalized effect of estrogens on blood pressure was not seen. Blood pressure should be monitored at regular intervals with estrogen use. Hypertriglyceridemia In patients with pre-existing hypertriglyceridemia, estrogen therapy may be associated with elevations of plasma triglycerides leading to pancreatitis and other complications. Impaired liver function and past history of cholestatic jaundice Estrogens may be poorly metabolized in patients with impaired liver function. For patients with a history of cholestatic jaundice associated with past estrogen use or with pregnancy, caution should be exercised, and in the case of recurrence, medication should be discontinued. Hypothyroidism Estrogen administration leads to increased thyroid-binding globulin (TBG) levels. Patients with normal thyroid function can compensate for the increased TBG by making more thyroid hormone, thus maintaining free T4 and T3 serum concentrations in the normal range. Patients dependent on thyroid hormone replacement therapy who are also receiving estrogens may require increased doses of their thyroid replacement therapy. These patients should have their thyroid function monitored to maintain their free thyroid hormone levels in an acceptable range. Fluid retention Estrogens may cause some degree of fluid retention. Because of this, patients who have conditions that might be influenced by this factor, such as a cardiac or renal dysfunction, warrant careful observation when estrogens are prescribed. Hypocalcemia Estrogens should be used with caution in individuals with severe hypocalcemia. Ovarian cancer The estrogen-plus-progestin substudy of the WHI reported that after an average follow-up of 5.6 years, the relative risk for ovarian cancer for estrogen-plus-progestin versus placebo was 1.58 (95% nCI, 0.77-3.24), but was not statistically significant. The absolute risk for estrogen-plus-progestin versus placebo was 4.2 versus 2.7 cases per 10,000 women-years. In some epidemiologic studies, the use of estrogen only products in particular for 10 or more years, has been associated with an increased risk of ovarian cancer. Other epidemiologic studies have not found these associations. Exacerbation of endometriosis Endometriosis may be exacerbated with administration of estrogens. Malignant transformation of residual endometrial implants have been reported in women treated posthysterectomy with estrogen-alone therapy. For patients known to have residual endometriosis post-hysterectomy, the addition of progestin should be considered. Exacerbation of other conditions Estrogens may cause an exacerbation of asthma, diabetes mellitus, epilepsy, migraine or porphyria, systemic lupus erythematosus, and hepatic hemangiomas and should be used with caution in women with these conditions. Photosensitivity/Photoallergy The effects of direct sun exposure to Divigel® application sites have not been evaluated in clinical trials. Nonclinical studies in guinea pigs showed no phototoxicity or photosensitivity. In addition, Divigel® has been shown to absorb light primarily at wavelengths below 290 nm. Therefore, Divigel® is not considered to have photosensitizing potential. Sunscreen application Studies conducted using other approved topical estrogen gel products have shown that sunscreens have the potential for changing the systemic exposure of topically applied estrogen gels. The effect of concomitant application of sunscreen and Divigel® to the same application site has not been clinically evaluated. Miscellaneous Alcohol based gels are flammable. Avoid fire, flame, or smoking until the gel has dried. Occlusion of the area where the topical drug product is applied with clothing or other barriers is not recommended until the gel is completely dried. Potential for Estradiol Transfer and Effects of Washing There is a potential for drug transfer from one individual to the other following physical contact of Divigel® application sites. In a study to evaluate transferability to males from their female contacts, there was some elevation of estradiol levels over baseline in the male subjects, however, the degree of transferability in this study was inconclusive. Patients are advised to avoid skin contact with other subjects until the gel is completely dried. The site of application should be covered (clothed) after drying. Washing the application site with soap and water 1 hour after application resulted in a 30 to 38% decrease in the mean total 24-hour exposure to estradiol. Therefore, patients should refrain from washing the application site for at least one hour after application. Information for Patients Physicians and pharmacists are advised to discuss the PATIENT INFORMATION leaflet with patients for whom they prescribe or dispense Divigel®. Laboratory Tests Estrogen administration should be initiated at the lowest dose approved for the treatment of moderate-to-severe vasomotor symptoms associated with menopause and then guided by clinical response rather than by serum hormone levels (e.g., estradiol, FSH). Carcinogenesis, Mutagenesis, Impairment of Fertility See BOXED WARNINGS, WARNINGS and PRECAUTIONS. Long-term continuous administration of natural and synthetic estrogens in certain animal species increases the frequency of carcinomas of the breast, uterus, cervix, vagina, testis and liver. Pregnancy Estrogen products, including Divigel®, should not be used in pregnancy. (See CONTRAINDICATIONS.) Nursing Mothers Estrogen administration to nursing mothers has been shown to decrease the quantity and quality of the milk. Detectable amounts of estrogens have been identified in the milk of mothers receiving estrogen therapy. Caution should be exercised when estrogen products, including Divigel®, are administered to a nursing woman. Pediatric Use Safety and efficacy of Divigel® in pediatric patients has not been established. Geriatric Use There have not been sufficient numbers of geriatric patients involved in studies utilizing Divigel® to determine whether those over 65 years of age differ from younger subjects in their response to Divigel®. Of the total number of subjects in the estrogen-alone substudy of the Women's Health Initiative (WHI), 46% (n=4,943) were 65 years and older, while 7.1% (n=767) were 75 years and older. There was a higher relative risk (CE versus placebo) of stroke in women less than 75 years of age compared to women 75 years and older. In the estrogen-alone substudy of the Women's Health Initiative Memory Study (WHIMS), a substudy of WHI, a population of 2,947 hysterectomized women, aged 65 to 79 years, was randomized to CE (0.625 mg per day) or placebo. After an average follow-up of 5.2 years, the relative risk (CE versus placebo) of probable dementia was 1.49 (95% CI, 0.83-2.66). The absolute risk of developing probable dementia with estrogen alone was 37 vs. 25 cases per 10,000 women-years with placebo. Of the total number of subjects in the estrogen-plus-progestin substudy of the WHI, 44% (n=7,320) were 65 years and older, while 6.6% (n=1,095) were 75 years and older. There was a higher relative risk (CE/MPA versus placebo) of stroke and invasive breast cancer in women 75 and older compared to women less than 75 years of age. In women greater than 75, the increased risk of non-fatal stroke and invasive breast cancer observed in the estrogenplus- progestin combination group compared to the placebo group was 75 vs. 24 per 10,000 women-years and 52 vs. 12 per 10,000 women years, respectively. In the estrogen-plus-progestin substudy of WHIMS, a population of 4,532 postmenopausal women, aged 65 to 79 years, was randomized to CE/MPA (CE 0.625 mg/2.5 mg daily) or placebo. In the estrogen-plus-progestin group, after an average follow-up of 4 years, the relative risk (CE/MPA versus placebo) of probable dementia was 2.05 (95% CI, 1.21-3.48). The absolute risk of developing probable dementia with CE/MPA was 45 vs. 22 cases per 10,000 women-years with placebo. Seventy-nine percent of the cases of probable dementia occurred in women that were older than 70 for the CE group, and 82 percent of the cases of probable dementia occurred in women who were older than 70 in the CE/MPA group. The most common classification of probable dementia in both the treatment groups and placebo groups was Alzheimer's disease. When data from the two populations were pooled as planned in the WHIMS protocol, the reported overall risk of probable dementia was 1.76 (95% CI, 1.19-2.60). Since both substudies were conducted in women aged 65 to 79 years, it is unknown whether these findings apply to younger postmenopausal women. (See BOXED WARNINGS, and WARNINGS, Dementia.) Last reviewed on RxList: 6/6/2012
This monograph has been modified to include the generic and brand name in many instances.