Anastrozole Medication Monograph

Anastrozole is an aromatase inhibitor that blocks the conversion of androgens (such as testosterone) into estrogen in the body. It lowers the level of circulating estradiol

Indications: Breast cancer:First-line treatment of locally-advanced or metastatic breast cancer (hormone receptor-positive or unknown) in postmenopausal women.High estrogen levels due to testosterone therapy (off-label use):used to lower estrogen levels in men on testosterone therapy. Male hypogonadism (off-label use): normalization of testosterone levels in in elderly men with borderline hypogonadism

Dosing (Adults): High estrogen levels due to testosterone therapy (off-label use): Males: Oral: 0.25 mg daily or

0.5 mg every other day.Male hypogonadism (off-label use): Males: Oral: 0.25- 1 mg twice weekly to daily

Dosing (Adults): Varies by indication, dosage form, type and severity of symptoms

Renal Dosing: No dosage adjustment necessary

Hepatic Impairment:Mild to moderate impairment or stable hepatic cirrhosis: No dosage adjustment necessary

Severe hepatic impairment: There are no dosage adjustments provided in the manufacturer’s labeling (has not been studied)Contraindications:Hypersensitivity to anastrozole or any component of the formulation; use in women who are or may become pregnant

Warnings/Precautions:

Decreased bone mineral density: Due to decreased circulating estrogen levels, anastrozole is associated with a reduction in bone mineral density (BMD); decreases (from baseline) in total hip and lumbar spine BMD have been reported. Patients with preexisting osteopenia are at higher risk for developing osteoporosis (Eastell 2008). When initiating anastrozole treatment, follow available guidelines for bone mineral density management; concurrent use of bisphosphonates may be useful in patients at risk for fractures

Hypercholesterolemia: Elevated total cholesterol levels (contributed to by LDL cholesterol increases) have been reported in patients receiving anastrozole; use with caution in patients with hyperlipidemias. Cholesterol levels should be monitored/managed in accordance with current guidelines for patients with LDL elevations

Hepatic impairment: Plasma concentrations in patients with stable hepatic cirrhosis were within the range of concentrations seen in normal subjects across all clinical trials. Has not been studied in patients with severe hepatic impairment

Ischemic disease: Patients with preexisting ischemic cardiac disease have an increased risk for ischemic cardiovascular events

Drug Interactions: : Estrogen Derivatives: May diminish the therapeutic effect of Anastrozole. Methadone: Aromatase Inhibitors may increase the serum concentration of Methadone. Tamoxifen: May decrease the serum concentration of Anastrozole

Please speak with your doctor or pharmacist about other possible drug interactions as this list is not all-inclusive

Adverse Reactions: Vasodilatation, fatigue, mood disorder, headache, upset stomach

Patient Education:

What should I tell my doctor about before taking this medication?

If you have an allergy to anastrozole or any other part of this drug, if you are pregnant or may be pregnant, other medications you take including those that are over-the-counter

When and how do I take this medication?

Anastrozole is usually given daily in females. Anastrozole is usually given daily, every other day, or a few times per week in males. Anastrozole may be administered with or without food

What side effects should I call my doctor about right away?

Signs of an allergic reaction like rash, hives, or itching; signs of liver problems like dark urine, feeling tired, not hungry, upset stomach or stomach pain, light-colored stools, throwing up, or yellow skin or eyes; signs of high blood pressure like very bad headache or dizziness, passing out, or change in eyesight; signs of a urinary tract infection (UTI) like blood in the urine, burning or pain when passing urine, feeling the need to pass urine often or right away, fever, lower stomach pain, or pelvic pain; weakness on 1 side of the body, trouble speaking or thinking, change in balance, drooping on one side of the face, or blurred eyesight; a burning, numbness, or tingling feeling that is not normal; swollen gland; bone pain; shortness of breath; swelling in the arms or legs; mood changes; low mood (depression); change in eyesight; breast pain; vaginal bleeding that is not normal; vaginal itching or discharge; testicular changes

People who have ever had a block in their heart blood vessels (ischemic heart disease) may have more signs of problems with blood flow to the heart