Overview
DESCRIPTION CombiPatch ® (estradiol/norethindrone acetate transdermal system) is an adhesive-based matrix transdermal patch designed to release both estradiol, an estrogen, and norethindrone acetate (NETA), a progestational agent, continuously upon application to intact skin. Two systems are available, providing the following in vivo delivery rates of estradiol and NETA.
Mechanism of Action
CLINICAL PHARMACOLOGY Endogenous estrogens are largely responsible for the development and maintenance of the female reproductive system and secondary sexual characteristics. Although circulating estrogens exist in a dynamic equilibrium of metabolic interconversions, estradiol is the principal intracellular human estrogen and is substantially more potent than its metabolites, estrone and estriol at the receptor level. The primary source of estrogen in normally cycling adult women is the ovarian follicle, which secretes 70 to 500 mcg of estradiol daily, depending on the phase of the menstrual cycle. After menopause, most endogenous estrogen is produced by conversion of androstenedione, secreted by the adrenal cortex, to estrone in the peripheral tissues.
Indications
- INDICATIONS AND USAGE CombiPatch is indicated in a woman with a uterus for: Treatment of moderate to severe vasomotor symptoms due to menopause. Treatment of moderate to severe symptoms of vulvar and vaginal atrophy due to menopause. When prescribing solely for the treatment of symptoms of vulvar and vaginal atrophy, topical vaginal products should be considered. Treatment of hypoestrogenism due to hypogonadism, castration, or primary ovarian failure.
Common Doses
- 0.05 mg
- 0.14 mg
- 0.25 mg
Dosage
DOSAGE AND ADMINISTRATION Generally, when estrogen therapy is prescribed for a postmenopausal woman with a uterus, a progestin should be considered to reduce the risk of endometrial cancer. A woman without a uterus generally does not need a progestin. In some cases, however, hysterectomized women with a history of endometriosis may need a progestin. Use of estrogen-alone or in combination with a progestin, should be with the lowest effective dose and for the shortest duration consistent with treatment goals and risks for the individual woman.
Black Box Warning
WARNING: CARDIOVASCULAR DISORDERS, BREAST CANCER, ENDOMETRIAL CANCER, AND PROBABLE DEMENTIA Estrogen Plus Progestin Therapy Cardiovascular Disorders and Probable Dementia Estrogen plus progestin therapy should not be used for the prevention of cardiovascular disease or dementia. (See CLINICAL STUDIES and WARNINGS , Cardiovascular Disorders and Probable Dementia ). The Women’s Health Initiative (WHI) estrogen plus progestin substudy reported an increased risk of deep vein thrombosis (DVT), pulmonary embolism (PE), stroke and myocardial infarction (MI) in postmenopausal women (50 to 79 years of...
Contraindications
- CONTRAINDICATIONS CombiPatch is contraindicated in women with any of the following conditions: Undiagnosed abnormal genital bleeding. Known, suspected, or history of breast cancer. Known or suspected estrogen-dependent neoplasia. Active DVT, PE, or history of these conditions. Active arterial thromboembolic disease (for example, stroke and MI), or a history of these conditions. Known anaphylactic reaction or angioedema or hypersensitivity with CombiPatch. Known liver impairment or disease. Known protein C, protein S, or antithrombin deficiency, or other known thrombophilic disorders.
Side Effects
- ADVERSE REACTIONS See BOXED WARNING , WARNINGS , and PRECAUTIONS . Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Table 9. All Adverse Reactions Regardless of Relationship Reported at a Frequency of Greater than or Equal to 5 percent with CombiPatch VASOMOTOR SYMPTOM STUDIES CombiPatch 0.05/0.14 mg per day† CombiPatch 0.05/0.
Interactions
- Drug Interactions No drug interaction studies have been conducted with CombiPatch. In vitro and in vivo studies have shown that estrogens are metabolized partially by cytochrome P450 3A4 (CYP3A4). Therefore, inducers or inhibitors of CYP3A4 may affect estrogen drug metabolism. Inducers of CYP3A4 such as St. John’s wort ( Hypericum perforatum ) preparations, anticonvulsants (e.g., phenobarbital, phenytoin and carbamazepine), phenylbutazone, and anti-infectives (e.g.