Reproductive & OB

Prevents/controls eclamptic seizures in preeclampsia. High-alert: monitor reflexes; antidote is calcium gluconate.

Drugs used to quiet preterm contractions for a short window — two to seven days — so antenatal corticosteroids can be given and the mother transferred. No medication is FDA-approved for tocolysis; all are used off-label. Terbutaline, a β2 agonist, carries a boxed warning against prolonged tocolysis; nifedipine and indomethacin are the most common agents in their classes.

Induces/augments labor and controls postpartum bleeding. High-alert: titrate to contractions, watch for tachysystole.

The uterine drugs beyond oxytocin: methylergonovine (an ergot) and carboprost (a prostaglandin F2α analog) contract the uterus to control postpartum bleeding; dinoprostone (prostaglandin E2) ripens the cervix before induction. Misoprostol is labeled only to protect the stomach from NSAIDs — and its boxed warning is about pregnancy.

Estrogen + progestin prevent ovulation; progestin-only methods (pill, implant, injection, IUS) rely on the progestin, and emergency contraception (levonorgestrel, ulipristal) is taken after unprotected sex. Boxed warnings: smoking after 35 → serious cardiovascular events with combined methods; bone-density loss with the medroxyprogesterone injection; complications of improper implant insertion. Estrogen drives VTE risk.

Estrogen treats hot flashes and vaginal atrophy after menopause, but in a woman with a uterus it must be paired with a progestin (or bazedoxifene) to protect the endometrium. Boxed warnings on most of these labels: endometrial cancer, stroke and clots, breast cancer and probable dementia. Also here: progesterone and oral medroxyprogesterone, mifepristone for medical termination of pregnancy (REMS), and fezolinetant, a non-hormonal hot-flash drug with a liver boxed warning.

SERMs bind the estrogen receptor but act as estrogen in some tissues and block it in others. Tamoxifen blocks estrogen in breast tissue (breast cancer treatment and risk reduction) but acts like estrogen in the uterus and on clotting — its boxed warning is uterine cancer, stroke and pulmonary embolism. Clomiphene blocks estrogen feedback in the brain to trigger ovulation; toremifene treats metastatic breast cancer with a QT boxed warning; ospemifene treats painful intercourse after menopause with an endometrial-cancer and cardiovascular boxed warning.

Anastrozole, letrozole and exemestane block aromatase, the enzyme that turns androgens into estrogens. After menopause that conversion in peripheral tissues is the main estrogen source, so these drugs treat hormone receptor-positive breast cancer in postmenopausal women — at the cost of bone loss, joint pain and higher cholesterol.

These drugs shut down the pituitary’s signal to the gonads. GnRH agonists (leuprolide, goserelin, triptorelin, nafarelin) first stimulate, then — given continuously — suppress LH and FSH, so testosterone and estrogen fall; the early surge can cause a tumor flare in prostate cancer. GnRH antagonists (degarelix, relugolix, elagolix, cetrorelix, ganirelix) block the receptor at once, with no flare. Uses: prostate cancer, endometriosis, fibroids, central precocious puberty and preventing a premature LH surge in fertility treatment.

Testosterone replaces what the testes no longer make in primary or hypogonadotropic hypogonadism, given as a gel, an injection or an oral capsule. Its risks follow its actions: more red cells, higher blood pressure, a larger prostate, suppressed sperm production — and virilization of anyone else it reaches. Danazol, a synthetic steroid with weak androgenic activity, suppresses the pituitary-ovarian axis to treat endometriosis and prevents attacks of hereditary angioedema.

These drugs block androgen action at three points. 5α-reductase inhibitors (finasteride, dutasteride) stop testosterone from becoming DHT, shrinking an enlarged prostate or treating male pattern hair loss; they lower PSA by about half and must not be handled by pregnant women. Androgen receptor inhibitors (flutamide, bicalutamide, nilutamide; enzalutamide, apalutamide, darolutamide) block the receptor in prostate cancer. Abiraterone blocks androgen synthesis (CYP17), can cause mineralocorticoid excess, and is labeled for use with a corticosteroid.

Sildenafil, tadalafil, vardenafil and avanafil block phosphodiesterase type 5, the enzyme that breaks down cGMP in the corpus cavernosum, so an erection triggered by sexual stimulation is stronger and lasts. They treat erectile dysfunction, and tadalafil also treats BPH. Because they are vasodilators, they are never combined with nitrates or riociguat, and are started cautiously with α-blockers.