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conjugated estrogens (Premarin, Enjuvia, Cenestin)

Premarin: equine source, Enjuvia: plant-derived synthetic. Indications: 1) hot flashes associated with menopause 2) osteoporosis 3) atrophic vaginitis, atrophy of vulva 4) vaginal bleeding 5) prostate cancer 5) hypogonadism & primary ovarian failure - ovariectomy Contraindications: 1) history of thromboembolism 2) NOT currently indicated for prevention or treatment of Alzheimer's disease or other dementias [2] 3) estrogen receptor-positive breast cancer 4) treatment with tamoxifen Dosage: 1) abnormal uterine bleeding: a) 25 mg IV/IM every 6 hours until bleeding stops b) 2.5-5 mg PO QD for 7-10 days c) 1.25 mg/day for 2 weeks 2) hypogonadism: a) 2.5-7.5 mg/day for 20 days b) stop for 10 days c) repeat until menses occur 3) menopause & osteoporosis: a) 0.625-1.25 mg for 1st 3 weeks of month b) 0.3 mg QD effective [5] 4) postpartum breast engorgement: a) 3.75 mg PO every 4 hours for 5 doses b) 1.25 mg every 4 hours for 5 days Tabs: 0.3, 0.45, 0.625, 0.9, 1.25, 2.5 mg. Transdermal: - NO increased risk of thrombosis? (no 1st pass metabolism) [5] Vaginal cream: apply QD (0.625 mg/g), also useful for epistaxis [10] Pharmacokinetics: - metabolized in the liver Pregnancy category X, Safety in lactation: no Adverse effects: 1) common (> 10%) - nausea, peripheral edema, enlargement of breasts, breast tenderness*, anorexia, bloating, pain at injection site 2) less common (1-10%) - vomiting, diarrhea, increased libido, headache 3) uncommon (< 1%) - intolerance to contact lenses, breast tumors, endometrial abnormalities, including breakthrough bleeding, amenorrhea, hypertension, venous thromboembolism, stroke, myocardial infarction, edema, depression, dizziness, anxiety, chloasma, melasma, rash, glucose intolerance, GI distress, increased triglycerides, increased LDL, cholestatic jaundice, increased susceptibilty to Candida infection 4) other - endometrial abnormalities, including breakthrough bleeding - breast cancer - increased risk of urinary incontinence [6] * breast tenderness minimal with dose of 0.3 mg QD [5] Drug interactions: 1) increased therapeutic effects & toxicity of antidepressants, beta-blockers, corticosteroids, theophylline 2) antibiotics, barbiturates, phenytoin, rifampin decrease effectiveness of premarin 3) premarin decreases effectiveness of thyroxine (synthroid) by increasing thyroxine-binding globulin & decreasing free thyroxine levels Mechanism of action: estrogen

Interactions

drug adverse effects of estrogens

General

estrogen

References

  1. The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
  2. Yaffe et al JAMA 279:688-695 1998
  3. Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998
  4. Kaiser Permanente Northern California Regional Drug Formulary, 1998
  5. Geriatrics Review Syllabus, American Geriatrics Society, 5th edition, 2002-2004
  6. Prescriber's Letter 10(6):33 2003
  7. Prescriber's Letter 12(2): 2005 New Drugs Approved by the FDA in 2004 Detail-Document#: 210216 (subscription needed) http://www.prescribersletter.com
  8. Department of Veterans Affairs, VA National Formulary
  9. Prescriber's Letter 13(5): 2006 Estrogen-containing hormone replacement products for postmenopausal women Detail-Document#: 220602 (subscription needed) http://www.prescribersletter.com
  10. Prescriber's Letter 13(10): 2006 Alternative or 'Off-label' Routes of Drug Administration Detail-Document#: 221012 (subscription needed) http://www.prescribersletter.com
  11. Deprecated Reference

Component-of

bazedoxifene/conjugated estrogens (Duavee) conjugated estrogens (Premarin)/methyltestosterone Estratest conjugated estrogens/medroxyprogesterone (Prempro, Premphase) conjugated estrogens (Premarin)/methyltestosterone Estratest