Metoprolol and Hydrochlorothiazide Extended-Release Tablets and Tamoxifen Citrate

• Generic Name: hydrochlorothiazide / metoprolol
• Dosage Forms: n.a.
• Other Brand Names: Dutoprol, Lopressor HCT

• It is used to treat high blood pressure.

• Generic Name: tamoxifen
• Dosage Forms: n.a.
• Other Brand Names: Soltamox, Nolvadex

An adjuvant to surgery and radiation therapy for the treatment of breast cancer in women with negative or positive axillary lymph nodes. Also reduces the occurrence of contralateral breast cancer in these women.

Palliative treatment of metastatic breast cancer in women. An alternative to ovarian ablative therapy (oophorectomy or radiation) in premenopausal women. Patients with estrogen receptor-positive tumors are more likely to respond.

Reduction of risk of invasive breast cancer in patients with DCIS following surgery and radiation therapy. Base decision regarding use on an individualized assessment of potential benefits and risks of therapy.

Reduction in the incidence of breast cancer in women at high risk for developing the disease. Base decision regarding use on an individualized assessment of potential benefits and risks of preventive therapy.

ASCO considers tamoxifen an option in premenopausal or postmenopausal women ≥35 years of age with either a 5-year projected risk for developing breast cancer of ≥1.67% (based on Gail risk model) or a history of lobular carcinoma in situ (LCIS).

Data regarding effect on breast cancer incidence in women with inherited mutations (e.g., BRCA1, BRCA2) are insufficient to support recommendations regarding tamoxifen use.

Palliative treatment of metastatic breast cancer in men.

Adjunct to surgery in the treatment of breast cancer in men with positive axillary lymph nodes; used alone or in conjunction with combination chemotherapy.

The high frequency of hormone receptors in tumors of men may explain the high response rate of male breast carcinoma to endocrine therapy. Treatment to date has been similar to that for women with breast cancer; however, experience in men is very limited.

Variations in genes responsible for tamoxifen metabolism may affect treatment decision (e.g., alternative drug or dosage requirement).

Exposure to endoxifen (major active metabolite of tamoxifen) is strongly associated with CYP2D6 metabolizer phenotype, and low endoxifen concentrations are associated with increased risk for disease recurrence in women receiving adjuvant tamoxifen therapy for breast cancer; however, the validity of CYP2D6 metabolizer phenotype as a predictor of the outcome of tamoxifen therapy is controversial.

Although some experts do not recommend use of CYP2D6 genotyping to guide treatment decisions in patients with hormone receptor-positive breast cancer based on available evidence, the Clinical Pharmacogenetics Implementation Consortium (CPIC) and other experts recommend that women with CYP2D6 poor-, intermediate-, or normal/intermediate-metabolizer phenotypes (activity scores of 0–1) receive adjuvant endocrine therapy with an alternative agent (e.g., aromatase inhibitor in postmenopausal women; aromatase inhibitor plus ovarian suppression in premenopausal women). If an aromatase inhibitor is contraindicated, CPIC and these experts state that an increased tamoxifen dosage of 40 mg daily may be considered, but endoxifen concentrations may still be suboptimal in those with a CYP2D6 poor-metabolizer phenotype.

Has been used to reduce the frequency of vaginal bleeding episodes and to reduce the rate of increase in bone age in girls with Albright syndrome (also known as McCune-Albright syndrome) and precocious puberty.

Long-term effects beyond one year not established. (See Pediatric Use under Cautions.)