Tamoxifen

Administration

  • Type: SERM
  • Dosage Forms: Tab 10mg, 20mg
  • Routes of Administration: Oral
  • Common Trade Names: Soltamox

Adult Dosing

Breast Cancer

  • 20 mg PO daily

Mastalgia

  • 10 mg PO daily x4 months

Pediatric Dosing

Precocious Puberty

  • For 2-10 yo
    • 20 mg PO daily

Special Populations

Pregnancy Rating

  • Category D: avoid use during pregnancy
  • Risk of teratogenicity and fetal death

Lactation risk

  • Avoid use while breastfeeding
  • Decreased milk production

Renal Dosing

  • Adult: Not defined
  • Pediatric: Not defined

Hepatic Dosing

  • Adult: Not defined
  • Pediatric: Not defined

Contraindications

  • Allergy to class/drug
  • Pregnancy
  • Breastfeeding
  • Undiagnosed vaginal bleeding
  • H/o thromboembolism
  • Warfarin anticoagulation

Adverse Reactions

Serious

Common

Pharmacology

  • Half-life: 5-7 days; active metabolite 14 days
  • Metabolism: Liver; CYP450: 2C9, 2D6, 3A4
  • Excretion: Feces primarily

Mechanism of Action

  • Selectively binds to estrogen receptors, producing estrogenic and anti-estrogenic effects
  • Estrogen antagonist in breast cancer cells
  • Estrogen antagonist in hypothalamus of premenopausal women
  • Unknown mechanism in McCune-Albright syndrome

Comments

See Also

References

Epocrates, UpToDate