PH7.1-9 | Endocrine Pharmacology — Glossary

Peripheral enzyme (type 1, liver/kidney) that converts T4 to the active T3; inhibited by PTU, high-dose propranolol, and hydrocortisone.

Enzyme that converts testosterone to the more potent dihydrotestosterone (DHT) in prostate, skin, and scalp; inhibited by finasteride (type 2) and dutasteride (types 1+2).

Life-threatening acute adrenal insufficiency triggered by stress in a patient with suppressed or destroyed adrenal axis; presents with hypotension, vomiting, hyponatraemia; treated with IV hydrocortisone 100 mg stat.

Severe life-threatening neutropenia — rare ADR of thionamides (0.1–0.3%); presents with sore throat and fever; requires immediate drug cessation.

Prostaglandin E1 (PGE1) analogue for erectile dysfunction; administered by intracavernosal injection or intraurethral pellet; effective when NO signalling is impaired.

AMP-activated protein kinase — an energy sensor activated by metformin that reduces hepatic gluconeogenesis and increases peripheral glucose uptake.

Enzyme (CYP19A1) converting androgens to oestrogens; expressed in adipose tissue, ovaries, brain; inhibited by letrozole and anastrozole.

Competitive oxytocin receptor antagonist; parenteral tocolytic; fewer maternal ADRs than β2 agonists; high cost limits use in resource-limited settings.

Stress fracture of the sub-trochanteric/femoral shaft associated with prolonged bisphosphonate use (>5 years); presents with prodromal thigh pain; X-ray shows lateral cortical beaking.

Insulin regimen using a once-daily long-acting insulin for basal needs combined with rapid-acting insulin at each meal; most closely mimics physiological insulin secretion.

Non-steroidal androgen receptor antagonist; used in prostate cancer; causes gynaecomastia due to relative oestrogen excess from AR blockade.

Synthetic analogue of pyrophosphate that binds hydroxyapatite and inhibits farnesyl pyrophosphate synthase in osteoclasts, causing osteoclast apoptosis and reduced bone resorption.

D2 receptor agonist — inhibits prolactin secretion from pituitary lactotrophs; first-line for prolactinoma; superior to bromocriptine in efficacy and tolerability.

Prodrug converted to methimazole in vivo; inhibits TPO; first-line antithyroid agent in non-pregnant adults. Teratogenic in the 1st trimester of pregnancy.

15-methyl-PGF2α — potent uterotonic for refractory PPH; CONTRAINDICATED in asthma (causes bronchoconstriction).

Second messenger generated by guanylyl cyclase in response to NO; causes cavernosal smooth muscle relaxation and penile erection; degraded by PDE5.

Selective oestrogen receptor modulator (SERM) — blocks ER at hypothalamus/pituitary, reducing oestrogen negative feedback, increasing endogenous FSH/LH, and inducing follicular development and ovulation.

Oral contraceptive pill containing ethinyl oestradiol + a progestogen; prevents ovulation (primary), thickens cervical mucus, and alters endometrium.

Non-hormonal intrauterine device; copper ions impair sperm function; >99% effective long-term; also the most effective emergency contraceptive (up to 120 hours post-coitus).

Fully human monoclonal antibody (IgG2) against RANK-L; inhibits osteoclast formation and survival; no renal dose adjustment; rebound fractures occur if stopped abruptly.

Long-acting, high-potency glucocorticoid (GC ~25–30× hydrocortisone); negligible mineralocorticoid activity; preferred for cerebral oedema, anti-emesis, fetal lung maturation, COVID-19.

Active androgen formed from testosterone by 5α-reductase; 5× greater AR affinity than testosterone; drives prostate growth, scalp androgenetic alopecia.

Depot medroxyprogesterone acetate 150 mg IM injection every 3 months; highly effective progestin-only contraceptive; may delay return to fertility up to 12–18 months.

Dipeptidyl peptidase-4 — the enzyme that rapidly degrades endogenous GLP-1 and GIP; DPP-4 inhibitors prolong incretin action.

Fetal vascular shunt between pulmonary artery and aorta kept patent by PGE2; indomethacin (NSAID) can cause premature closure — restricted to <32 weeks gestation.

Estimated glomerular filtration rate — used to assess renal function and guide antidiabetic drug dosing and contraindication thresholds.

Ergot alkaloid causing tetanic uterine contraction; used for PPH post-delivery; contraindicated for labour induction and in hypertension/pre-eclampsia.

Subdermal progestogen implant (Nexplanon); releases etonogestrel for 3 years; most effective reversible contraceptive; suppresses ovulation.

Diabetic ketoacidosis occurring with near-normal blood glucose levels; a recognised adverse effect of SGLT2 inhibitors, particularly perioperatively.

Type-2 5α-reductase inhibitor; 5 mg for BPH (reduces prostate volume, reduces PSA ~50%); 1 mg for androgenetic alopecia; ADRs: sexual dysfunction.

Potent synthetic mineralocorticoid (MC ~125–150× hydrocortisone); used for replacement in Addison's disease and CAH; causes sodium retention and potassium excretion.

Fracture Risk Assessment Tool — calculates 10-year probability of major osteoporotic fracture using clinical risk factors with or without BMD; guides treatment decisions in osteopenic range.

Glucose-dependent insulinotropic polypeptide — an incretin hormone from K-cells; synergises with GLP-1 in the dual agonist tirzepatide.

Glucagon-like peptide-1 — an incretin hormone secreted by intestinal L-cells that stimulates insulin release and suppresses glucagon in a glucose-dependent manner.

Cytoplasmic nuclear receptor that, when bound by glucocorticoid, translocates to the nucleus to transactivate anti-inflammatory genes and transrepress pro-inflammatory transcription factors (NF-κB, AP-1).

Bone loss caused by prolonged glucocorticoid therapy; rapid in the first 3–6 months; prevented by concurrent bisphosphonate + calcium + vitamin D from day one of prescription.

Hypothalamic decapeptide released in pulses; stimulates pituitary gonadotrophs to release LH and FSH. Receptor is a GPCR — continuously stimulated receptors downregulate.

Glycated haemoglobin — reflects mean plasma glucose over 2–3 months; target <7% for most T2DM adults.

LH-like glycoprotein hormone — used as the LH surge trigger in ART when dominant follicle ≥18 mm; stimulates Leydig cells in males (used in male hypogonadotropic infertility).

Heart failure with reduced ejection fraction — defined as LVEF <40%; SGLT2 inhibitors have proven outcome benefit in this condition.

Hospitalisation for heart failure — a key secondary endpoint in SGLT2i and DPP-4i cardiovascular outcome trials.

Hypothalamic-pituitary-adrenal axis — CRH stimulates ACTH, which drives cortisol synthesis; suppressed by long-term exogenous glucocorticoids, causing adrenal atrophy.

Infertility caused by insufficient FSH/LH from the pituitary (hypothalamic or pituitary failure) — treated with gonadotropins or pulsatile GnRH.

Somatomedin C — produced by liver in response to GH; mediates GH's anabolic/growth effects; stable plasma level makes it the preferred biomarker for acromegaly monitoring.

High-concentration testosterone produced locally by Leydig cells under LH stimulation; required for spermatogenesis in Sertoli cells; suppressed by exogenous testosterone via HPG negative feedback.

ATP-sensitive potassium channel on pancreatic β-cells; closure by sulfonylureas or elevated ATP triggers insulin secretion.

Aromatase inhibitor — reduces peripheral oestrogen synthesis → relieves FSH negative feedback centrally → follicular development. Preferred first-line for PCOS ovulation induction (PCOSACT trial, NEJM 2014).

Long-acting GnRH agonist analogue; continuous administration downregulates pituitary GnRH receptors → LH/FSH suppression (chemical castration); pulsatile pump delivery stimulates gonadotropins.

Levonorgestrel 1.5 mg taken within 72 hours (up to 120 hours) post-coitus — emergency contraceptive; delays/prevents ovulation; NOT abortifacient.

Synthetic T4 prohormone; standard replacement for hypothyroidism; taken fasting; dose 1.6 mcg/kg/day; start low in elderly/cardiac patients.

Synthetic T3 — active, fast-onset; used in myxoedema coma and specialist T4+T3 combination therapy.

Anti-inflammatory protein upregulated by glucocorticoids; inhibits phospholipase A2, blocking arachidonic acid release and the prostaglandin/leukotriene cascade.

Progesterone supplementation after ovulation (vaginal or IM) in ART cycles to support endometrial decidualisation and early embryo implantation.

Major adverse cardiovascular events — composite endpoint of CV death, non-fatal MI, and non-fatal stroke used in CV outcome trials.

Tocolytic and fetal neuroprotective agent (<32 weeks); Mg²⁺ competes with Ca²⁺ and blocks NMDA receptors; antidote = calcium gluconate IV.

Antiprogestogen — used in medical termination of pregnancy (with misoprostol); NOT an emergency contraceptive in standard use.

Synthetic PGE1 analogue; thermostable; used for cervical ripening, induction (no prior scar), and PPH; oral/SL/vaginal/rectal routes.

Severe hypothyroid emergency — hypothermia, bradycardia, altered sensorium; treated with IV liothyronine, IV hydrocortisone, rewarming, and ventilatory support.

Calcium channel blocker (dihydropyridine); blocks L-type Ca²⁺ channels in myometrium; first-line oral tocolytic.

Somatostatin analogue (SSTR2/5 agonist); inhibits GH secretion; used in acromegaly, carcinoid syndrome, VIPoma; available in LAR (monthly depot) formulation.

Decoy receptor secreted by osteoblasts that sequesters RANK-L, blocking osteoclast activation; mimicked pharmacologically by denosumab.

Rare serious ADR of bisphosphonates and denosumab — avascular bone death in the jaw triggered by dental procedures; more common with high-dose IV use in oncology.

Complication of gonadotropin (and clomiphene) therapy — excessive follicular development → high VEGF → vascular permeability → ascites, pleural effusion, thromboembolism in severe cases.

Posterior pituitary nonapeptide; stimulates OTR (Gq-coupled) → Ca²⁺ release → myometrial contraction; used IV for labour induction and IM/IV for PPH.

Randomised controlled trial (NEJM 2014) comparing letrozole vs clomiphene for ovulation induction in PCOS — letrozole achieved significantly higher live birth rate (27.5% vs 19.1%) with fewer multiple gestations.

Enzyme in cavernosal smooth muscle that hydrolyses cGMP, terminating the erectile signal; inhibited by sildenafil, tadalafil, vardenafil.

Number of pregnancies per 100 woman-years of contraceptive use; lower = more effective.

GH receptor antagonist — modified GH molecule that binds but does not activate the GH receptor; lowers IGF-1 in refractory acromegaly; GH levels may rise (expected).

Peroxisome proliferator-activated receptor gamma — nuclear receptor activated by thiazolidinediones (pioglitazone) to improve insulin sensitivity in adipose, muscle, and liver.

Blood loss >500 mL within 24 hours of delivery; most commonly due to uterine atony; treated with stepwise uterotonic therapy.

Most widely used synthetic glucocorticoid for chronic inflammatory disease; GC potency 4× hydrocortisone, low MC activity; oral bioavailability high; active form (prednisone is the prodrug).

Most common functioning pituitary adenoma; secretes excess prolactin causing galactorrhoea, amenorrhoea, and infertility; treated first-line with dopamine agonists.

Antithyroid thionamide; inhibits TPO AND peripheral T4→T3 conversion; preferred in 1st trimester pregnancy and thyroid storm; hepatotoxicity risk limits long-term use.

Subcutaneous programmable pump delivering GnRH in physiological pulses (every 60–90 minutes) — used for ovulation induction in hypogonadotropic hypogonadism; mimics hypothalamic pulsatile GnRH release.

Oral radioiodine concentrated in thyroid; beta radiation destroys follicular cells; definitive treatment for Graves' disease, toxic nodule; contraindicated in pregnancy.

Selective oestrogen receptor modulator (SERM) — oestrogen agonist in bone, antagonist in breast/uterus; reduces vertebral but NOT hip fractures; increases DVT risk.

Receptor activator of NF-κB ligand — secreted by osteoblasts; binds RANK on osteoclast precursors to activate osteoclastogenesis and bone resorption.

Anti-sclerostin monoclonal antibody; dual anabolic (increases bone formation) and anti-resorptive; 12-month treatment; contraindicated within 12 months of MI or stroke.

Protein secreted by osteocytes that inhibits Wnt/β-catenin signalling in osteoblasts, suppressing bone formation; targeted by romosozumab.

Sodium-glucose cotransporter 2 — responsible for reabsorbing ~90% of filtered glucose in the proximal renal tubule; inhibited by empagliflozin, dapagliflozin, canagliflozin.

First PDE5 inhibitor — amplifies NO/cGMP in cavernosal smooth muscle during sexual stimulation; duration 4–6 hours; contraindicated with nitrates.

Hypothalamic hormone (and GI hormone) that inhibits GH release from pituitary somatotrophs; pharmacological analogues (octreotide, lanreotide) mimic its action.

Patient identification document stating the patient is on corticosteroid therapy — essential in emergencies to trigger stress dosing and prevent adrenal crisis from drug withholding.

Standard deviations from mean BMD of a healthy young adult reference population by DEXA; T-score ≤ –2.5 = osteoporosis; –1.0 to –2.5 = osteopenia.

PDE5 inhibitor with the longest half-life (17–36 hours); available as daily low-dose (5 mg) for continuous ED treatment; also approved for BPH+ED; contraindicated with nitrates.

Recombinant PTH(1-34) — given as daily SC injection; intermittent PTH stimulates osteoblast proliferation and new bone formation; lifetime maximum 24 months.

Androgen replacement for symptomatic hypogonadism; available as IM esters, transdermal gel, or oral undecanoate; monitor testosterone, haematocrit, PSA.

Synthetic ACTH(1-24); used in the short Synacthen test for adrenal insufficiency diagnosis; also used to treat infantile spasms (West syndrome).

Enzyme that catalyses iodide oxidation and organification steps in thyroid hormone synthesis; inhibited by both carbimazole/methimazole and PTU.

Life-threatening decompensated thyrotoxicosis — high fever, tachycardia, altered sensorium; treated with PTU + Lugol's (after PTU) + propranolol + hydrocortisone.

A dual GIP/GLP-1 receptor agonist approved for T2DM and obesity; distinct from selective GLP-1 RAs (liraglutide, semaglutide) in its dual receptor activity and greater weight-loss efficacy.

Drug that inhibits uterine contractions in preterm labour; goal is 24–48 hours delay for fetal corticosteroid lung maturation.

GR-mediated upregulation of anti-inflammatory genes (e.g. lipocortin/annexin A1) in the nucleus — one arm of glucocorticoid anti-inflammatory action.

GR-mediated blocking of pro-inflammatory transcription factors (NF-κB, AP-1) in the nucleus — prevents transcription of IL-1, IL-6, TNF-α, COX-2.

Selective progesterone receptor modulator (SPRM) — 30 mg single dose; emergency contraceptive effective up to 120 hours; more effective than levonorgestrel at 72–120 hours.

Drug that stimulates uterine (myometrial) contractions; classified as oxytocin, ergot alkaloids, or prostaglandins.

Deep vein thrombosis or pulmonary embolism — risk increased 3–4× with combined OCP (oestrogen induces clotting factors); not significantly increased with progestin-only methods.

World Health Organization Medical Eligibility Criteria — categorises safety of contraceptive methods for specific medical conditions (1=always use, 4=do not use).

Paradoxical inhibition of thyroid organification by high-dose iodide — the basis for Lugol's iodine use in thyroid storm and pre-operative preparation; transient (escape occurs after 1–2 weeks).