9.5 Sex Hormones & Contraceptives
Sex hormone pharmacology includes estrogens, progestins, and androgens for hormone replacement, contraception, and treatment of hormone-sensitive conditions.
Estrogens
Forms:
- • Ethinyl estradiol: Oral contraceptives (synthetic, potent)
- • Conjugated estrogens: Hormone replacement (Premarin)
- • Estradiol: Transdermal patches, vaginal creams
Uses:
- • Oral contraception (with progestin)
- • Hormone replacement therapy (HRT) in menopause
- • Hypogonadism, Turner syndrome
⚠️ Adverse Effects:
- • Thromboembolism: DVT, PE, stroke (↑ coagulation factors)
- • Endometrial cancer (unopposed estrogen)
- • Breast cancer risk (long-term HRT)
- • Nausea, breast tenderness, headache
- • Cholestasis, gallstones
- Contraindicated: History of VTE, breast cancer, pregnancy
Progestins
Forms:
- • Medroxyprogesterone: HRT, contraception (Depo-Provera)
- • Norethindrone, levonorgestrel: Oral contraceptives
- • Etonogestrel: Implant (Nexplanon)
Uses:
- • Oral contraception (combined or progestin-only)
- • HRT (protect endometrium from estrogen)
- • Abnormal uterine bleeding
- • Endometriosis
Adverse Effects:
- • Weight gain, bloating
- • Irregular bleeding
- • Mood changes, depression
- • Bone loss (high-dose medroxyprogesterone)
Oral Contraceptives
Combined (Estrogen + Progestin)
Suppress ovulation (↓ LH/FSH), thicken cervical mucus, thin endometrium. >99% effective with perfect use.
- • Monophasic, biphasic, triphasic formulations
- • Benefits: Regulate menses, ↓ ovarian/endometrial cancer, ↓ acne
- ⚠️ Avoid in: Smoking + age >35, VTE history, migraine with aura
Progestin-Only ("Mini-Pill")
Thicken cervical mucus (primary), suppress ovulation (inconsistent). Safe in breastfeeding, smokers, VTE risk.
- • Norethindrone, desogestrel
- • Must take at same time daily (strict timing)
- • Irregular bleeding common
Androgens & Antiandrogens
Testosterone
Forms:
- • IM injections (testosterone cypionate, enanthate)
- • Transdermal gels, patches
- • Buccal, nasal formulations
Uses:
- • Male hypogonadism
- • Delayed puberty
- • Gender-affirming therapy (FTM)
Adverse Effects:
- • Polycythemia (↑ erythropoiesis; monitor Hct)
- • Acne, oily skin
- • Gynecomastia (aromatization to estrogen)
- • Testicular atrophy, ↓ sperm count
- • Hepatotoxicity (oral 17α-alkylated forms)
- • Sleep apnea exacerbation
- ⚠️ Contraindicated: Prostate cancer, male breast cancer
Antiandrogens
Finasteride & Dutasteride
- • 5α-reductase inhibitors (block DHT formation)
- • Benign prostatic hyperplasia (BPH)
- • Male pattern baldness (finasteride 1 mg)
- ⚠️ Sexual dysfunction, ↓ libido, gynecomastia
Flutamide, Bicalutamide
- • Nonsteroidal androgen receptor antagonists
- • Prostate cancer (with GnRH agonist)
- • Hepatotoxicity (monitor LFTs)
Spironolactone
- • Aldosterone antagonist with antiandrogen effects
- • Hirsutism, acne (PCOS)
- • Gender-affirming therapy (MTF)
Selective Estrogen Receptor Modulators (SERMs)
Tamoxifen
- • Breast: Antagonist (treats ER+ breast cancer)
- • Uterus: Agonist (↑ endometrial cancer risk)
- • Bone: Partial agonist (maintains density)
- ⚠️ Hot flashes, VTE, endometrial cancer
Raloxifene
- • Breast: Antagonist (prevents breast cancer)
- • Uterus: Antagonist (no endometrial cancer risk)
- • Bone: Agonist (treats osteoporosis)
- • Lower VTE risk than tamoxifen