Premarin

Prem·a·rin (prm-rn)

A trademark for a drug preparation of conjugated estrogens.

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estrogens, conjugated Warning - Hazardous drug!

C.E.S. (CA), Congest (CA), Premarin, Premarin Intravenous

Pharmacologic class: Estrogen

Therapeutic class: Replacement hormone, antineoplastic, antiosteoporotic

Pregnancy risk category X

FDA Boxed Warning

• Drug increases endometrial cancer risk in postmenopausal women.
• Drug may increase risk of cardiovascular disease, breast cancer, and dementia.
• Drug shouldn't be used during pregnancy.
• Warnings may vary somewhat among specific brands. See package insert for complete warning information.

Action

Bind to nuclear receptors in responsive tissues (such as female genital organs, breasts, and pituitary gland), enhancing DNA, RNA, and protein synthesis. In androgen-dependent prostate cancer, compete for androgen receptor sites, inhibiting androgen activity. Also decrease pituitary release of follicle-stimulating and luteinizing hormones.

Availability

Powder for injection: 25 mg/5 ml

Tablets: 0.3 mg, 0.625 mg, 0.9 mg, 1.25 mg

Vaginal cream: 0.625 mg/g

⊘Indications and dosages

➣ Ovariectomy; primary ovarian failure

Adults: 1.25 mg P.O. daily continuously or in cycles of 3 weeks on and 1 week off

➣ Osteoporosis and menopausal symptoms

Adults: 0.3 to 1.25 mg P.O. daily continuously or in cycles of 3 weeks on and 1 week off

➣ Female hypogonadism

Adults: 0.3 to 0.625 mg P.O. daily, given in cycles of 3 weeks on and 1 week off

➣ Inoperable breast cancer in men and postmenopausal women

Adults: 10 mg P.O. t.i.d. for 3 months or more

➣ Inoperable prostate carcinoma

Adults: 1.25 to 2.5 mg P.O. t.i.d.

➣ Uterine bleeding caused by hormonal imbalance

Adults: 25 mg I.M. or I.V., repeated in 6 to 12 hours if necessary

➣ Atrophic vaginitis

Adults: 0.5 to 2 g (vaginal cream) intravaginally daily in cycles of 3 weeks on and 1 week off

Contraindications

• Hypersensitivity to drug or its components
• Thromboembolic disease (current or previous)
• Undiagnosed vaginal bleeding
• Breast or reproductive system cancer (except metastatic disease)
• Estrogen-dependent neoplasms
• Pregnancy

Precautions

Use cautiously in:
• cardiovascular disease, severe hepatic or renal disease, asthma, bone disease, migraine, seizures, breast disease
• family history of breast or genital tract cancer
• breastfeeding patients.

Administration

• Know that drug is compatible with dextrose 5% in water and normal saline solution.

Route	Onset	Peak	Duration
P.O., I.M.	Unknown	Unknown	6-12 hr
I.V.	Rapid	Unknown	6-12 hr
Intravaginal	Unknown	Unknown	Unknown

Adverse reactions

CNS: headache, dizziness, lethargy, depression, asthenia, paresthesia, syncope, cerebrovascular accident (CVA), seizures

CV: hypertension, chest pain, myocardial infarction (MI), thromboembolism

EENT: contact lens intolerance, worsening of myopia or astigmatism, otitis media, sinusitis, rhinitis, pharyngitis

GI: nausea, vomiting, diarrhea, abdominal cramps, bloating, enlarged abdomen, dyspepsia, flatulence, gastritis, gastroenteritis, hemorrhoids, colitis, gallbladder disease, anorexia, pancreatitis

GU: urinary incontinence, dysuria, urinary tract infection, amenorrhea, dysmenorrhea, endometrial hyperplasia, vaginal candidiasis, leukorrhea, vaginal hemorrhage, genital eruptions, gynecomastia, breast tenderness, breast enlargement or secretion, reduced libido, erectile dysfunction, testicular atrophy, increased risk of breast cancer, endometrial cancer, hemolytic uremic syndrome

Hepatic: cholestatic jaundice, hepatic adenoma

Metabolic: hyperglycemia, hypercalcemia, sodium and fluid retention, reduced carbohydrate tolerance

Musculoskeletal: leg cramps, back pain, skeletal pain

Respiratory: upper respiratory tract infection, bronchitis, pulmonary embolism

Skin: acne, oily skin, pigmentation changes, urticaria, pruritus, erythema nodosum, hemorrhagic eruption, skin hypertrophy, hirsutism, alopecia, erythema multiforme

Other: edema, weight changes, increased appetite, hypersensitivity reaction

Interactions

Drug-drug. Corticosteroids: enhanced corticosteroid effects

CYP450 inducers (such as barbiturates, rifampin): decreased estrogen efficacy

Hypoglycemics, warfarin: altered requirement for these drugs

Phenytoin: loss of seizure control

Tamoxifen: interference with tamoxifen effects

Tricyclic antidepressants: reduced antidepressant effects

Drug-diagnostic tests. Antithrombin III, folate, low-density lipoproteins, pyridoxine, total cholesterol, urine pregnanediol: decreased values

Cortisol; factors VII, VIII, IX, and X; glucose; high-density lipoproteins; phospholipids; prolactin; prothrombin; sodium; triglycerides: increased values

Metyrapone test: false decrease

Thyroid function tests: false interpretation

Drug-food. Caffeine: increased caffeine blood level

Drug-herbs. Black cohosh: increased risk of adverse reactions

Red clover: interference with estrogen effects

Saw palmetto: antiestrogenic effects

St. John's wort: decreased drug blood level and effects

Drug-behaviors. Smoking: increased risk of adverse cardiovascular reactions

Patient monitoring

• Monitor liver function test results and assess abdomen for enlarged liver.
• Evaluate patient for breast tenderness and swelling. As needed, give analgesics and apply cool compresses.
• Monitor fluid intake and output, and weigh patient daily.
☞ Know that drug increases risk of thromboembolism, CVA, and MI.
• Check serum phosphatase level in patients with prostate cancer.
• Monitor calcium, glucose, and folic acid levels.
• Evaluate bone density annually.

Patient teaching

☞ Teach patient to recognize and report signs and symptoms of thromboembolism.
☞ Caution patient not to take drug if she is or plans to become pregnant.
• Tell patient to report breakthrough vaginal bleeding.
• Recommend that patient have routine breast examinations.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, foods, herbs, and behaviors mentioned above.