Endocrine Pharmacology — MCQs
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All of the following agents are tocolytics, EXCEPT?
Which of the following drugs can act as goitrogens?
What is the most common route of administration for insulin?
Which of the following is NOT an adverse effect of glucocorticoids?
Which of the following is not an insulin analogue?
Which of the following is an amylin analogue?
Mifepristone is an antiprogestin agent. All of the following are indications for the use of mifepristone, EXCEPT:
All of the following drugs may cause hirsutism, except?
Which of the following is an androgen receptor blocking drug?
What is true about Cinacalcet?
Endocrine Pharmacology Indian Medical PG Practice Questions and MCQs
Question 571: All of the following agents are tocolytics, EXCEPT?
- A. Ritodrine
- B. Salbutamol
- C. Isoxsuprine
- D. Misoprostol (Correct Answer)
Explanation: **Explanation:** The core concept here is the difference between **Tocolytics** (agents that relax the uterine muscle to delay preterm labor) and **Oxytocics** (agents that stimulate uterine contractions). **Why Misoprostol is the correct answer:** Misoprostol is a **Prostaglandin E1 (PGE1) analogue**. Instead of relaxing the uterus, it stimulates uterine contractions and promotes cervical ripening. Therefore, it is an **Oxytocic** agent used for medical abortion, induction of labor, and management of postpartum hemorrhage (PPH). It is contraindicated when the goal is to stop labor. **Analysis of Incorrect Options (Tocolytics):** * **Ritodrine & Salbutamol (Options A & B):** These are **Beta-2 ($\beta_2$) Adrenergic Agonists**. They increase intracellular cAMP in the myometrium, which leads to smooth muscle relaxation. Ritodrine was historically the only FDA-approved drug specifically for tocolysis. * **Isoxsuprine (Option C):** Another $\beta$-agonist used traditionally as a uterine relaxant, though its use has declined due to cardiovascular side effects like tachycardia and hypotension. **High-Yield Clinical Pearls for NEET-PG:** * **First-line Tocolytics:** Currently, **Nifedipine** (Calcium Channel Blocker) and **Atosiban** (Oxytocin receptor antagonist) are preferred due to better safety profiles compared to $\beta$-agonists. * **Magnesium Sulfate ($MgSO_4$):** Used for neuroprotection in preterm labor (up to 32 weeks) rather than primary tocolysis. * **Indomethacin:** A COX inhibitor used as a tocolytic; however, it must be avoided after 32 weeks of gestation due to the risk of premature closure of the **Ductus Arteriosus**.
Question 572: Which of the following drugs can act as goitrogens?
- A. P.A.S
- B. Thiocyanate
- C. Antithyroid drugs
- D. All of the above (Correct Answer)
Explanation: **Explanation:** A **goitrogen** is any substance that interferes with thyroid hormone synthesis, leading to a compensatory increase in Thyroid Stimulating Hormone (TSH) from the anterior pituitary. Elevated TSH levels cause hyperplasia and hypertrophy of the thyroid gland, resulting in a **goiter**. * **Thiocyanate (Option B):** These are monovalent anions that act as competitive inhibitors of the **Sodium-Iodide Symporter (NIS)**. By blocking the active transport of iodide into the thyroid follicle, they deplete the gland of the raw material needed for hormone synthesis. * **Antithyroid drugs (Option C):** Drugs like Propylthiouracil (PTU) and Methimazole inhibit the enzyme **Thyroid Peroxidase (TPO)**. This prevents the oxidation of iodide and the subsequent organification of iodine into tyrosine residues. * **P.A.S (Para-aminosalicylic acid) (Option D):** This older anti-tubercular drug also inhibits TPO and interferes with iodine coupling, similar to the mechanism of sulfonamides. Since all three substances interfere with the production of $T_3$ and $T_4$, they trigger the feedback loop that increases TSH, making **"All of the above"** the correct answer. **High-Yield Clinical Pearls for NEET-PG:** * **Lithium:** A well-known goitrogen that inhibits the release of thyroid hormones from thyroglobulin. * **Amiodarone:** Can cause both hypothyroidism (Wolff-Chaikoff effect) and hyperthyroidism (Jod-Basedow phenomenon) due to its high iodine content. * **Dietary Goitrogens:** Glucosinolates found in cruciferous vegetables (cabbage, cauliflower) can inhibit iodide uptake. * **Mechanism Tip:** Most goitrogens act by inhibiting either the **Iodide Trap (NIS)** or **Thyroid Peroxidase (TPO)**.
Question 573: What is the most common route of administration for insulin?
- A. Intramuscular
- B. Subcutaneous (Correct Answer)
- C. Intravenous
- D. Intradermal
Explanation: **Explanation:** **Why Subcutaneous (SC) is the correct answer:** The subcutaneous route is the standard and most common route for insulin administration in both clinical and home settings. The subcutaneous tissue provides a **slow and consistent absorption** rate, mimicking the physiological basal secretion of insulin. It is preferred because it is relatively painless, allows for easy self-administration by patients, and carries a lower risk of rapid, life-threatening hypoglycemia compared to the intravenous route. **Analysis of Incorrect Options:** * **Intramuscular (IM):** While insulin can be absorbed via IM injection, it is not preferred because absorption is faster and more unpredictable than SC, leading to greater glycemic variability. It is also more painful for the patient. * **Intravenous (IV):** This route is reserved for **emergencies** such as Diabetic Ketoacidosis (DKA) or Hyperosmolar Hyperglycemic State (HHS). Only **Regular (soluble) insulin** is typically given IV. It is not used for routine maintenance due to its very short half-life and high risk of sudden hypoglycemia. * **Intradermal:** This route is not used for insulin delivery as the absorption is inefficient and the technique is difficult for frequent daily dosing. **High-Yield Clinical Pearls for NEET-PG:** * **Preferred Sites:** The **abdomen** has the fastest and most consistent absorption, followed by the arms, thighs, and buttocks. * **Lipodystrophy:** Patients must rotate injection sites to prevent lipohypertrophy, which can impair insulin absorption. * **Insulin Pumps:** These also utilize the subcutaneous route for Continuous Subcutaneous Insulin Infusion (CSII). * **Inhaled Insulin:** (Afrezza) is an alternative rapid-acting option but is contraindicated in smokers and patients with COPD/Asthma.
Question 574: Which of the following is NOT an adverse effect of glucocorticoids?
- A. Hypoglycemia (Correct Answer)
- B. Cataract
- C. Peptic ulcer
- D. Infections
Explanation: **Explanation:** Glucocorticoids (like Prednisolone and Dexamethasone) are steroid hormones that significantly impact metabolism, immunity, and electrolyte balance. **Why Hypoglycemia is the correct answer:** Glucocorticoids are **diabetogenic**. They increase blood glucose levels by stimulating gluconeogenesis in the liver and decreasing peripheral glucose uptake in muscle and adipose tissue. Therefore, they cause **hyperglycemia**, not hypoglycemia. Steroid-induced diabetes is a well-known clinical complication. **Analysis of Incorrect Options:** * **Cataract:** Long-term use of glucocorticoids is associated with the development of **posterior subcapsular cataracts** and increased intraocular pressure (glaucoma). * **Peptic Ulcer:** Steroids inhibit prostaglandin synthesis (via Phospholipase A2 inhibition), which reduces gastric mucosal protection. When combined with NSAIDs, the risk of peptic ulceration and GI bleeding increases significantly. * **Infections:** Glucocorticoids are potent immunosuppressants. They inhibit T-cell function, decrease cytokine production (IL-1, IL-2), and cause lymphopenia. This predisposes patients to opportunistic infections and can mask signs of inflammation. **High-Yield NEET-PG Clinical Pearls:** * **Mnemonic for Steroid Side Effects:** "CUSHINGOID" (Cataracts, Up [BP], Skin thinning, Hypertension/Hirsutism, Infections, Necrosis [Avascular necrosis of femoral head], Glycosuria, Osteoporosis, Immunosuppression, Diabetes). * **Osteoporosis:** Steroids are the most common cause of drug-induced osteoporosis (they inhibit osteoblasts and decrease calcium absorption). * **Growth Retardation:** A critical concern in pediatric patients due to premature closure of epiphyseal plates. * **Withdrawal:** Abrupt cessation after chronic use can lead to **Acute Adrenal Insufficiency** (Addisonian Crisis) due to HPA-axis suppression. Always taper the dose.
Question 575: Which of the following is not an insulin analogue?
- A. Insulin glargine
- B. Insulin lispro
- C. Actrapid (Correct Answer)
- D. Insulin aspart
Explanation: **Explanation:** The distinction between **Insulin Analogues** and **Human Insulin** is a high-yield topic for NEET-PG. Insulin analogues are developed by modifying the amino acid sequence of human insulin using recombinant DNA technology to alter its pharmacokinetic profile (onset and duration). **Why Actrapid is the correct answer:** **Actrapid** is a brand name for **Regular (Neutral) Human Insulin**. It is not an analogue; rather, it is identical in structure to the native human insulin molecule. It is classified as "Short-acting" insulin. Because it forms hexamers at the injection site, its absorption is delayed, leading to a peak effect in 2–3 hours. **Analysis of incorrect options (Analogues):** * **Insulin Lispro & Insulin Aspart:** These are **Rapid-acting analogues**. Lispro is created by switching Lysine and Proline at positions B28 and B29. Aspart involves replacing Proline with Aspartic acid at B28. These modifications prevent hexamer formation, allowing for faster absorption and "prandial" (mealtime) coverage. * **Insulin Glargine:** This is a **Long-acting (Basal) analogue**. It is modified to be soluble at acidic pH but precipitates at physiological pH in subcutaneous tissue. This results in a slow, "peakless" release lasting 24 hours. **High-Yield Clinical Pearls for NEET-PG:** * **Ultra-short acting:** Lispro, Aspart, Glulisine (Mnemonic: **L**ive **A**s **G**old). * **Ultra-long acting:** Degludec (longest half-life, >40 hours), Glargine, Detemir. * **Inhaled Insulin:** Afrezza (Rapid-acting powder). * **Drug of choice in DKA:** Intravenous Regular Insulin (Actrapid). * **Safe in pregnancy:** Regular insulin, Aspart, and Lispro are commonly used; Glargine is also now considered safe.
Question 576: Which of the following is an amylin analogue?
- A. Exenatide
- B. Sitagliptin
- C. Pramlintide (Correct Answer)
- D. Glucomannan
Explanation: **Explanation:** **Pramlintide** is a synthetic analogue of **amylin**, a peptide hormone co-secreted with insulin by pancreatic beta cells. Amylin plays a crucial role in postprandial glucose regulation by slowing gastric emptying, suppressing glucagon secretion, and promoting satiety. In patients with diabetes (both Type 1 and Type 2), amylin is deficient. Pramlintide is the only amylin analogue currently used clinically; it is administered subcutaneously before meals to control postprandial glucose spikes. **Analysis of Incorrect Options:** * **Exenatide (Option A):** This is a **GLP-1 receptor agonist** (Incretin mimetic). While it also slows gastric emptying and suppresses glucagon, its mechanism involves mimicking Glucagon-Like Peptide-1, not amylin. * **Sitagliptin (Option B):** This is a **DPP-4 inhibitor**. It works by preventing the breakdown of endogenous GLP-1 and GIP, thereby increasing insulin secretion and decreasing glucagon levels. * **Glucomannan (Option D):** This is a water-soluble **dietary fiber** derived from the konjac root. It is used as a bulk-forming laxative and sometimes as a weight-loss supplement, but it has no hormonal analogue activity. **High-Yield Clinical Pearls for NEET-PG:** * **Indication:** Pramlintide is unique because it is the only non-insulin drug approved for **Type 1 Diabetes** (in addition to Type 2). * **Side Effects:** The most common side effect is **nausea**. * **Black Box Warning:** It can cause severe **hypoglycemia** when used with insulin; therefore, the pre-prandial insulin dose must be reduced by 50% when starting Pramlintide. * **Administration:** It must be injected separately from insulin (cannot be mixed in the same syringe) because the pH difference causes precipitation.
Question 577: Mifepristone is an antiprogestin agent. All of the following are indications for the use of mifepristone, EXCEPT:
- A. Abortion
- B. Cushing's syndrome
- C. Postpartum hemorrhage (PPH) (Correct Answer)
- D. Cervical ripening
Explanation: **Explanation:** Mifepristone is a potent **progesterone receptor antagonist** (and at higher doses, a glucocorticoid receptor antagonist). Understanding its mechanism is key to identifying its clinical applications. **Why Postpartum Hemorrhage (PPH) is the correct answer:** Mifepristone is **not** used in PPH; in fact, it would be counterproductive. Management of PPH requires **uterotonics** (like Oxytocin, Misoprostol, or Carboprost) to cause uterine contraction and stop bleeding. Mifepristone, by blocking progesterone, increases uterine sensitivity to prostaglandins but does not provide the acute, powerful contractions needed to manage active hemorrhage. **Analysis of Incorrect Options:** * **Abortion:** Mifepristone is the drug of choice for medical termination of pregnancy (MTP) up to 7 weeks (often used up to 9-10 weeks). It causes decidual breakdown and sensitizes the myometrium to prostaglandins. * **Cushing’s Syndrome:** At high doses, Mifepristone acts as a **glucocorticoid receptor antagonist**. It is FDA-approved for controlling hyperglycemia in patients with endogenous Cushing’s syndrome (specifically those with Type 2 Diabetes who are not surgical candidates). * **Cervical Ripening:** By blocking progesterone, Mifepristone promotes cervical softening and ripening, making it useful for induction of labor in specific clinical scenarios (e.g., intrauterine fetal death). **High-Yield Clinical Pearls for NEET-PG:** * **MTP Regimen:** Usually 200 mg Mifepristone (oral) followed 36–48 hours later by 400–800 µg Misoprostol (vaginal/oral). * **Emergency Contraception:** A single dose of Mifepristone (10–25 mg) can be used as emergency contraception. * **Other Uses:** It is also investigated for use in endometriosis and uterine fibroids due to its anti-proliferative effects on the endometrium.
Question 578: All of the following drugs may cause hirsutism, except?
- A. Danazol
- B. Phenytoin
- C. Norethisterone
- D. Flutamide (Correct Answer)
Explanation: **Explanation:** The correct answer is **Flutamide**. **1. Why Flutamide is the correct answer:** Hirsutism is defined as the excessive growth of terminal hair in females in a male-pattern distribution, primarily driven by excess androgens. **Flutamide** is a **pure non-steroidal anti-androgen** that acts by competitively inhibiting androgen receptors. Because it blocks the action of dihydrotestosterone (DHT) at the hair follicle, it is actually used as a **treatment** for hirsutism, rather than being a cause of it. **2. Analysis of incorrect options:** * **Danazol:** A synthetic steroid with weak androgenic properties used in endometriosis. It frequently causes androgenic side effects, including hirsutism, acne, and weight gain. * **Phenytoin:** This antiepileptic drug is a well-known cause of "non-androgenic" hirsutism (often more accurately termed hypertrichosis), likely due to its effect on hair follicle cycles. * **Norethisterone:** A first/second-generation progestin derived from 19-nortestosterone. It retains significant androgenic activity, which can lead to hirsutism and oily skin. **3. Clinical Pearls for NEET-PG:** * **Androgenic Hirsutism Causes:** Danazol, Norethisterone, Anabolic steroids, Metyrapone. * **Non-Androgenic Hirsutism/Hypertrichosis Causes:** Phenytoin, Cyclosporine, Minoxidil, Diazoxide (Mnemonic: **P**olice **C**an **M**ake **D**og). * **Anti-androgens used to treat Hirsutism:** Spironolactone (blocks receptors + inhibits synthesis), Finasteride (5-alpha reductase inhibitor), and Flutamide. * **Drug of Choice:** Combined Oral Contraceptive Pills (OCPs) are generally the first-line medical treatment for hirsutism in PCOS.
Question 579: Which of the following is an androgen receptor blocking drug?
- A. Tamoxifen
- B. Cyproterone acetate (Correct Answer)
- C. Mifepristone
- D. Nalondrone
Explanation: **Explanation:** **Cyproterone acetate** is a potent synthetic steroid that acts as a competitive antagonist at the **androgen receptor**. By blocking the binding of dihydrotestosterone (DHT) and testosterone to their receptors, it inhibits androgenic effects in target tissues. Additionally, it has progestational activity which suppresses the secretion of gonadotropins (LH and FSH), further reducing testosterone production. It is clinically used in the management of hirsutism in females, precocious puberty in boys, and as palliative treatment for prostatic carcinoma. **Analysis of Incorrect Options:** * **Tamoxifen (Option A):** A Selective Estrogen Receptor Modulator (SERM). It acts as an estrogen antagonist in the breast (used in breast cancer) but as an agonist in the bone and endometrium. * **Mifepristone (Option C):** A potent **progesterone receptor antagonist** (used for medical abortion) and a glucocorticoid receptor antagonist (used in Cushing’s syndrome). * **Nalondrone (Option D):** Likely a distractor or misspelling of **Nandrolone**, which is an **anabolic steroid** (androgen agonist), not a blocker. **High-Yield Clinical Pearls for NEET-PG:** * **Other Androgen Receptor Blockers:** Flutamide, Bicalutamide (non-steroidal, used in prostate cancer), and Spironolactone (also blocks aldosterone receptors). * **5-alpha Reductase Inhibitors:** Finasteride and Dutasteride (prevent conversion of Testosterone to DHT; used in BPH and male pattern baldness). * **GnRH Analogues:** Leuprolide and Goserelin (cause medical castration via pituitary desensitization). * **Side Effect:** A common side effect of androgen blockers in males is **gynecomastia**.
Question 580: What is true about Cinacalcet?
- A. Calcimimetic (Correct Answer)
- B. Calciuric
- C. Decreases calcium absorption
- D. Calcitonin
Explanation: **Explanation:** **Cinacalcet** is a first-in-class **calcimimetic** drug. It works by increasing the sensitivity of the calcium-sensing receptors (CaSR) located on the chief cells of the parathyroid gland to extracellular calcium [1]. By mimicking the action of calcium, it suppresses the secretion of Parathyroid Hormone (PTH) without increasing serum calcium levels [1]. * **Why Option A is Correct:** As a calcimimetic, Cinacalcet "tricks" the parathyroid gland into sensing higher levels of calcium than actually exist, thereby inhibiting PTH release [1]. It is primarily used in the management of **Secondary Hyperparathyroidism** (in Chronic Kidney Disease) and **Parathyroid Carcinoma** [1]. * **Why Option B is Incorrect:** While Cinacalcet lowers serum calcium, it is not primarily classified as a "calciuric" (a drug whose main action is increasing urinary calcium excretion, like loop diuretics). * **Why Option C is Incorrect:** Cinacalcet does not directly inhibit the intestinal absorption of calcium; its primary site of action is the parathyroid gland. * **Why Option D is Incorrect:** Calcitonin is a hormone secreted by the parafollicular (C-cells) of the thyroid gland that lowers blood calcium. Cinacalcet is a synthetic small molecule, not a form of calcitonin. **High-Yield Clinical Pearls for NEET-PG:** * **Indication:** Secondary hyperparathyroidism in patients on dialysis and primary hyperparathyroidism in those unable to undergo surgery [1]. * **Side Effect:** The most common side effect is **hypocalcemia** (monitor serum calcium closely) [1]. * **Etelcalcetide:** A newer, intravenous calcimimetic used for similar indications. * **Contraindication:** Do not start treatment if the initial serum calcium is below the lower limit of the normal range.
Practice by Chapter
Hypothalamic and Pituitary Hormones
Practice Questions
Thyroid Drugs and Antithyroid Agents
Practice Questions
Insulin and Oral Hypoglycemic Agents
Practice Questions
Adrenocorticosteroids
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Sex Hormones: Estrogens and Progestins
Practice Questions
Androgens and Anabolic Steroids
Practice Questions
Hormonal Contraceptives
Practice Questions
Drugs Affecting Calcium Metabolism
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Drugs for Osteoporosis
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Pharmacological Management of Obesity
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