Endocrine Pharmacology
Endocrine pharmacology covers the drugs that replace, mimic or block hormones - insulin and oral antidiabetics, thyroid drugs, corticosteroids, and sex hormones. These notes summarise each group with its key drugs, uses and adverse effects, followed by a 20-question practice set as you requested.
Insulin and Antidiabetic Drugs
- Insulin is used in type 1 diabetes and severe type 2; the main risk is hypoglycaemia.
- Insulin types by onset/duration: rapid (lispro, aspart), short (regular), intermediate (NPH), long (glargine, detemir).
- Metformin (a biguanide) is first-line in type 2 diabetes; it reduces hepatic glucose output and does not cause hypoglycaemia alone.
- Sulfonylureas (glibenclamide, glimepiride) stimulate insulin release and can cause hypoglycaemia and weight gain.
Thyroid and Antithyroid Drugs
- Hypothyroidism is treated with levothyroxine (T4), the synthetic thyroid hormone.
- Hyperthyroidism is treated with antithyroid drugs - carbimazole and propylthiouracil (PTU) - which block hormone synthesis.
- PTU also blocks peripheral conversion of T4 to T3 and is preferred in the first trimester of pregnancy.
- Radioactive iodine (I-131) and beta-blockers (for symptom control) are also used.
Corticosteroids
Glucocorticoids (e.g. hydrocortisone, prednisolone, dexamethasone) are powerful anti-inflammatory and immunosuppressant drugs.
- Uses: inflammation, allergy, autoimmune disease, asthma, and replacement in Addison's disease.
- Adverse effects (long-term): Cushingoid features, osteoporosis, hyperglycaemia, peptic ulcer, infection risk.
- Never stop long-term steroids abruptly - taper to avoid adrenal insufficiency.
Sex Hormones and Others
- Oral contraceptives combine an oestrogen and a progestin to prevent ovulation.
- Oxytocin contracts the uterus and is used to induce labour; it is a posterior pituitary hormone.
- Bisphosphonates and calcium/vitamin D are used in osteoporosis rather than hormones alone.
Key Terms
- Hypoglycaemia
- Abnormally low blood glucose - the main adverse effect of insulin and sulfonylureas.
- Levothyroxine
- Synthetic T4 used as replacement therapy in hypothyroidism.
- Glucocorticoid
- A corticosteroid such as prednisolone with anti-inflammatory and immunosuppressant actions.
Practice Quiz — 20 Questions
-
The most important adverse effect of insulin therapy is:
- A.Hypertension
- B.Hypoglycaemia
- C.Constipation
- D.Hair loss
B. Hypoglycaemia — Excess insulin lowers blood glucose too far, causing hypoglycaemia. -
First-line drug for type 2 diabetes in most guidelines is:
- A.Insulin
- B.Metformin
- C.Glibenclamide
- D.Pioglitazone
B. Metformin — Metformin is first-line and does not cause hypoglycaemia on its own. -
Metformin belongs to which class?
- A.Sulfonylurea
- B.Biguanide
- C.DPP-4 inhibitor
- D.SGLT2 inhibitor
B. Biguanide — Metformin is a biguanide. -
Which drug class stimulates insulin secretion from the pancreas?
- A.Biguanides
- B.Sulfonylureas
- C.Alpha-glucosidase inhibitors
- D.Statins
B. Sulfonylureas — Sulfonylureas (e.g. glimepiride) stimulate insulin release. -
Which is a long-acting insulin analogue?
- A.Lispro
- B.Regular insulin
- C.Glargine
- D.Aspart
C. Glargine — Glargine provides a long, flat basal action. -
Hypothyroidism is treated with:
- A.Carbimazole
- B.Levothyroxine
- C.Propylthiouracil
- D.Radioiodine
B. Levothyroxine — Levothyroxine (T4) replaces the deficient hormone. -
Which drug is used for hyperthyroidism?
- A.Levothyroxine
- B.Carbimazole
- C.Metformin
- D.Insulin
B. Carbimazole — Carbimazole blocks thyroid hormone synthesis. -
The antithyroid drug preferred in the first trimester of pregnancy is:
- A.Carbimazole
- B.Propylthiouracil
- C.Radioiodine
- D.Levothyroxine
B. Propylthiouracil — PTU is generally preferred early in pregnancy. -
Radioactive iodine used to treat hyperthyroidism is:
- A.I-125
- B.I-131
- C.I-123
- D.I-127
B. I-131 — I-131 is used therapeutically to ablate thyroid tissue. -
Which is a glucocorticoid?
- A.Prednisolone
- B.Metformin
- C.Levothyroxine
- D.Oxytocin
A. Prednisolone — Prednisolone is a synthetic glucocorticoid. -
A long-term adverse effect of glucocorticoids is:
- A.Weight loss
- B.Osteoporosis
- C.Hypoglycaemia
- D.Bradycardia
B. Osteoporosis — Chronic steroids cause osteoporosis, among other effects. -
Long-term corticosteroids should be stopped by:
- A.Sudden withdrawal
- B.Gradual tapering
- C.Doubling the dose first
- D.Switching to insulin
B. Gradual tapering — Tapering avoids acute adrenal insufficiency. -
Corticosteroid replacement is essential in:
- A.Cushing's syndrome
- B.Addison's disease
- C.Type 1 diabetes
- D.Hyperthyroidism
B. Addison's disease — Addison's disease is adrenal insufficiency needing steroid replacement. -
Combined oral contraceptives usually contain:
- A.Oestrogen and progestin
- B.Insulin and glucagon
- C.T3 and T4
- D.Cortisol and aldosterone
A. Oestrogen and progestin — They combine an oestrogen with a progestin to block ovulation. -
Oxytocin is mainly used to:
- A.Lower blood sugar
- B.Induce labour
- C.Treat hypothyroidism
- D.Reduce inflammation
B. Induce labour — Oxytocin contracts the uterus and induces or augments labour. -
Which hormone is released by the posterior pituitary?
- A.Insulin
- B.Oxytocin
- C.Thyroxine
- D.Cortisol
B. Oxytocin — Oxytocin and ADH are released from the posterior pituitary. -
Which drug does NOT typically cause hypoglycaemia when used alone?
- A.Regular insulin
- B.Glibenclamide
- C.Metformin
- D.Glimepiride
C. Metformin — Metformin alone does not usually cause hypoglycaemia. -
Dexamethasone is primarily a:
- A.Mineralocorticoid
- B.Glucocorticoid
- C.Sex hormone
- D.Thyroid hormone
B. Glucocorticoid — Dexamethasone is a potent glucocorticoid with little mineralocorticoid effect. -
A patient on long-term steroids is at increased risk of:
- A.Infections
- B.Weight loss
- C.Low blood pressure
- D.Bradycardia
A. Infections — Immunosuppression from steroids raises infection risk. -
Propylthiouracil (PTU) reduces thyroid activity by:
- A.Replacing T4
- B.Blocking hormone synthesis (and T4 to T3 conversion)
- C.Stimulating the thyroid
- D.Removing the thyroid
B. Blocking hormone synthesis (and T4 to T3 conversion) — PTU blocks synthesis and peripheral conversion of T4 to T3.
References
- Katzung, Basic & Clinical Pharmacology (standard reference)
- Rang & Dale's Pharmacology - Endocrine system