Endocrine Pharmacology — MCQs

Endocrine Pharmacology Indian Medical PG Practice Questions and MCQs

Question 251: Corticosteroids cause all of the following except:

A. Muscular hypertrophy (Correct Answer)
B. Peptic ulceration
C. Psychosis
D. Suppression of pituitary-adrenal axis

Explanation: **Explanation:** Corticosteroids, specifically glucocorticoids, are primarily **catabolic** in nature regarding peripheral tissues. The correct answer is **Muscular hypertrophy** because steroids actually cause **muscular atrophy (myopathy)**. 1. **Why Muscular Hypertrophy is incorrect:** Glucocorticoids promote the breakdown of muscle proteins into amino acids (proteolysis) to provide substrates for gluconeogenesis in the liver. This leads to muscle wasting and proximal myopathy, characterized by weakness in the shoulder and hip girdles. 2. **Peptic Ulceration:** Steroids increase gastric acid and pepsin secretion while reducing the protective mucosal barrier (by inhibiting prostaglandin synthesis). This increases the risk of peptic ulcers, especially when co-administered with NSAIDs. 3. **Psychosis:** Steroids have significant CNS effects. They can cause a range of psychiatric symptoms, from mild euphoria and insomnia to severe "steroid psychosis," mania, or depression. 4. **Suppression of Pituitary-Adrenal Axis:** Exogenous steroids exert negative feedback on the hypothalamus (CRH) and anterior pituitary (ACTH). Prolonged use leads to atrophy of the adrenal cortex, which can result in acute adrenal insufficiency if the drug is stopped abruptly. **High-Yield Clinical Pearls for NEET-PG:** * **Redistribution of Fat:** Steroids cause "Centripetal Obesity" (Buffalo hump, Moon facies, and potbelly) despite peripheral muscle wasting. * **Bone Health:** They cause osteoporosis by inhibiting osteoblast activity and decreasing calcium absorption. * **Ocular Effects:** Long-term use is a known risk factor for **Glaucoma** and **Posterior Subcapsular Cataracts**. * **Metabolic:** They cause hyperglycemia (Steroid-induced Diabetes) by increasing gluconeogenesis and decreasing peripheral glucose uptake.

Question 252: Insulin zinc suspension (Lente insulin) is classified as which type of insulin based on its action profile?

A. Rapid acting
B. Short acting
C. Intermediate acting (Correct Answer)
D. Long acting

Explanation: ### Explanation **1. Why the Correct Answer is Right (Intermediate Acting):** Insulin Zinc Suspension (Lente insulin) is a mixture of two types of zinc-insulin crystals: **30% Semilente** (amorphous/rapidly absorbed) and **70% Ultralente** (crystalline/slowly absorbed). This specific ratio results in an intermediate duration of action, typically lasting 18–24 hours. The addition of zinc in a buffered acetate solution causes the insulin to precipitate, slowing its absorption from the subcutaneous site compared to soluble insulin. **2. Why the Other Options are Wrong:** * **Rapid-acting (A):** These are insulin analogues like **Lispro, Aspart, and Glulisine**. They have a modified amino acid sequence that prevents hexamer formation, allowing for near-instant absorption. * **Short-acting (B):** This refers to **Regular (Soluble) Insulin**. It is the only form that can be given intravenously. Its action starts within 30 minutes and lasts 6–8 hours. * **Long-acting (D):** This category includes **Ultralente** (in its pure form) and modern analogues like **Glargine, Detemir, and Degludec**. Glargine, for example, precipitates at physiological pH to provide a "peakless" basal coverage for over 24 hours. **3. High-Yield Clinical Pearls for NEET-PG:** * **Lente vs. NPH:** Both are intermediate-acting. However, **NPH (Neutral Protamine Hagedorn)** uses protamine as the retarding agent, whereas **Lente** uses zinc. * **Compatibility:** Lente insulin should **not** be mixed with Regular insulin because the excess zinc in Lente can bind to the regular insulin and delay its onset of action. * **Trend:** Lente insulins are now largely obsolete in clinical practice, having been replaced by NPH and long-acting analogues (Glargine) which have more predictable absorption profiles.

Question 253: Carboprost, used for 2nd-trimester abortion, is an analogue of which prostaglandin?

A. PGE2
B. PGF2α (Correct Answer)
C. PGI2
D. PGD2

Explanation: Explanation: **Carboprost (15-methyl PGF2α)** is a synthetic analogue of naturally occurring **Prostaglandin F2α** [1]. The addition of a methyl group at the C-15 position increases its metabolic stability and duration of action by resisting rapid degradation by the enzyme 15-OH prostaglandin dehydrogenase [1]. **Why PGF2α is correct:** Prostaglandins of the F series are potent stimulators of uterine smooth muscle (myometrium) throughout pregnancy. Carboprost induces forceful uterine contractions and cervical ripening, making it highly effective for: 1. **Second-trimester abortions** (13–20 weeks) [1]. 2. **Postpartum Hemorrhage (PPH):** It is a second-line agent used when oxytocin fails, as it causes powerful uterine contraction to control bleeding [1]. **Analysis of Incorrect Options:** * **PGE2 (Dinoprostone):** While also used for cervical ripening and abortion, Carboprost specifically belongs to the F2α class [1]. PGE2 is primarily used for induction of labor at term [1]. * **PGI2 (Prostacyclin):** Analogues like Epoprostenol or Iloprost are used as vasodilators and inhibitors of platelet aggregation, primarily in pulmonary hypertension. * **PGD2:** This prostaglandin is involved in allergic responses and sleep regulation; it has no clinical application in obstetrics. **High-Yield NEET-PG Pearls:** * **Side Effects:** Carboprost frequently causes diarrhea and vomiting (due to GI smooth muscle stimulation) and can cause **bronchoconstriction** [1]. * **Contraindication:** It is strictly contraindicated in patients with **Asthma** [1]. * **Other PG Analogues:** * **Misoprostol:** PGE1 analogue (used for medical abortion with Mifepristone) [1]. * **Alprostadil:** PGE1 analogue (used to keep ductus arteriosus patent). * **Latanoprost:** PGF2α analogue (used in Glaucoma).

Question 254: A teenage girl complains of increased facial hair growth. Her menstrual cycle is regular and she has normal body weight. Which of the following may be used in the treatment of hirsutism, EXCEPT?

A. Spironolactone
B. Flutamide
C. Cyproterone
D. Mifepristone (Correct Answer)

Explanation: **Explanation:** The clinical presentation describes **hirsutism** (excessive terminal hair growth in a male-pattern distribution). Treatment for hirsutism focuses on reducing androgen production or blocking androgen receptors. **Why Mifepristone is the Correct Answer:** **Mifepristone (RU-486)** is a potent **progesterone and glucocorticoid receptor antagonist**. It is primarily used for medical termination of pregnancy (up to 7 weeks) and in the management of Cushing’s syndrome (to control hyperglycemia). It has **no significant anti-androgenic activity**; therefore, it is ineffective in treating hirsutism. **Analysis of Incorrect Options:** * **Spironolactone (A):** An aldosterone antagonist that also possesses significant anti-androgenic properties. It works by blocking androgen receptors and inhibiting 5-alpha reductase. It is a first-line pharmacological treatment for hirsutism. * **Flutamide (B):** A pure non-steroidal anti-androgen that competes with testosterone and dihydrotestosterone (DHT) for binding to androgen receptors. While effective for hirsutism, its use is often limited by potential hepatotoxicity. * **Cyproterone Acetate (C):** A synthetic progestin with potent anti-androgenic activity. It blocks androgen receptors and suppresses LH/FSH, reducing ovarian androgen production. It is frequently used in combination with ethinylestradiol (as a COCP) for hirsutism. **NEET-PG High-Yield Pearls:** * **Finasteride:** Another option for hirsutism; it acts by inhibiting **Type II 5-alpha reductase**, preventing the conversion of testosterone to the more potent DHT. * **Eflornithine:** A topical cream used for hirsutism that inhibits the enzyme **ornithine decarboxylase** in hair follicles. * **First-line treatment:** Combined Oral Contraceptive Pills (COCPs) are generally the initial choice for hirsutism in women not seeking pregnancy.

Question 255: What is the primary mechanism of action of brimonidine in glaucoma?

A. Decreased aqueous humor secretion (Correct Answer)
B. Increased trabecular outflow
C. Increased uveoscleral outflow
D. Reduced vitreous humor volume

Explanation: **Explanation:** **Brimonidine** is a highly selective **alpha-2 ($\alpha_2$) adrenergic agonist** used in the management of open-angle glaucoma and ocular hypertension. **1. Why Option A is Correct:** The primary mechanism of brimonidine is the **reduction of aqueous humor production**. It acts on $\alpha_2$ receptors located on the ciliary body epithelium. Stimulation of these G-protein coupled receptors leads to a decrease in intracellular cAMP, which in turn inhibits the active secretion of aqueous humor by the ciliary processes. **2. Analysis of Other Options:** * **Option B (Increased trabecular outflow):** This is the primary mechanism of **Miotics** (e.g., Pilocarpine), which contract the ciliary muscle to open the trabecular meshwork. * **Option C (Increased uveoscleral outflow):** While brimonidine has a secondary, delayed effect of increasing uveoscleral outflow (via prostaglandin release), its **primary** and immediate action is the suppression of aqueous production. Note: **Prostaglandin analogs** (e.g., Latanoprost) act exclusively via this pathway. * **Option D (Reduced vitreous humor volume):** This is the mechanism of **Hyperosmotic agents** like IV Mannitol or oral Glycerol, used for rapid reduction of intraocular pressure in acute angle-closure glaucoma. **Clinical Pearls for NEET-PG:** * **Dual Action:** Brimonidine is unique because it both decreases production and increases uveoscleral outflow (though production decrease is the primary effect). * **Blood-Brain Barrier:** Unlike Apraclonidine, Brimonidine is more lipid-soluble and can cross the BBB, potentially causing **central CNS depression and apnea in children**. It is strictly **contraindicated in infants and children under 2 years**. * **Side Effects:** Can cause follicular conjunctivitis and "apraclonidine-like" lid retraction.

Question 256: Prostaglandin derivatives are used in the following conditions, except:

A. Cervical ripening
B. Abortion
C. Abortion
D. Abortion (Correct Answer)

Explanation: **Explanation:** Prostaglandin (PG) derivatives are widely used in obstetrics and gynecology due to their ability to cause cervical softening and uterine contractions. However, the question as presented contains a typographical error in the options. In the context of NEET-PG, this question typically tests the **contraindications** or **limitations** of PG use. **Understanding the Correct Answer:** Prostaglandins (like **Misoprostol/PGE1** and **Dinoprostone/PGE2**) are standard treatments for **Cervical Ripening** and **Abortion** (both medical and missed). If the "Except" option is meant to be a condition where they are avoided, it usually refers to **Previous Cesarean Section** (due to risk of uterine rupture) or **Glaucoma** (specifically for PGF2α, though Latanoprost is used topically). *Note: Given the repetitive options provided, the intended "Except" answer in standard exams is often "To maintain patency of Ductus Arteriosus" (which uses PGE1) vs "To close it" (which uses NSAIDs).* **Analysis of Options:** * **Cervical Ripening:** PGE2 (Dinoprostone) gel or inserts are the gold standard for ripening the cervix before induction of labor. * **Abortion:** Misoprostol (PGE1) is used in combination with Mifepristone for medical termination of pregnancy (MTP) up to 9-11 weeks and for second-trimester abortions. * **Postpartum Hemorrhage (PPH):** Carboprost (PGF2α) and Misoprostol are used to control bleeding by causing uterine contraction. **High-Yield NEET-PG Pearls:** 1. **Alprostadil (PGE1):** Used to keep the Ductus Arteriosus open in cyanotic heart disease. 2. **Latanoprost (PGF2α):** First-line for Open-Angle Glaucoma (increases uveoscleral outflow). 3. **Epoprostenol (PGI2):** Used in Pulmonary Hypertension. 4. **Misoprostol Side Effect:** Most common side effect is diarrhea. It is also used for NSAID-induced peptic ulcers.

Question 257: Mifepristone is a:

A. Progesterone antagonist (Correct Answer)
B. Oestrogen antagonist
C. Both
D. None

Explanation: **Explanation:** **Mifepristone (RU-486)** is a synthetic steroid that acts primarily as a **competitive progesterone receptor antagonist**. In the presence of progesterone, it binds to the progesterone receptors (PR-A and PR-B) with high affinity, preventing the hormone from exerting its effects. Since progesterone is essential for the maintenance of the decidua and the stability of the pregnancy, Mifepristone leads to decidual breakdown, uterine contractions, and cervical softening. **Analysis of Options:** * **Option A (Correct):** Mifepristone blocks progesterone receptors. It is used clinically for medical termination of pregnancy (MTP) up to 7 weeks (49 days) or 9 weeks (63 days) depending on guidelines, usually followed by a prostaglandin like Misoprostol. * **Option B (Incorrect):** Mifepristone does not have significant estrogen antagonist activity. Drugs that block estrogen receptors are called Selective Estrogen Receptor Modulators (SERMs) like Tamoxifen or Clomiphene. * **Option C & D (Incorrect):** As it is specifically a progesterone (and glucocorticoid) antagonist, these options are invalid. **NEET-PG High-Yield Pearls:** 1. **Glucocorticoid Antagonism:** At higher doses, Mifepristone also acts as a potent **Glucocorticoid Receptor (GR) antagonist**. It is FDA-approved for treating hyperglycemia in patients with **Cushing’s Syndrome** (specifically those with endogenous ACTH production or adrenal carcinoma). 2. **MTP Protocol:** The standard regimen involves 200 mg of Mifepristone orally, followed 36–48 hours later by 400–800 mcg of Misoprostol (PGE1 analogue). 3. **Emergency Contraception:** Mifepristone can be used as an emergency contraceptive (10–25 mg) by delaying ovulation. 4. **Other Uses:** It is also investigated for use in uterine fibroids and endometriosis due to its anti-progestogenic effects.

Question 258: Mifepristone is most useful for the treatment of which condition?

A. Fibroids
B. Ectopic pregnancy
C. Threatened abortion
D. Molar pregnancy (Correct Answer)

Explanation: **Explanation:** **Mifepristone** is a potent competitive antagonist at both progesterone and glucocorticoid receptors. In the context of **Molar Pregnancy** (Hydatidiform mole), mifepristone is used as a medical adjunct for cervical ripening and uterine evacuation. It blocks progesterone receptors in the decidua, leading to trophoblastic separation and increased uterine sensitivity to prostaglandins, which facilitates the expulsion of the molar tissue. **Analysis of Options:** * **A. Fibroids:** While mifepristone can reduce the size of leiomyomas by inhibiting progesterone-dependent growth, it is not the "most useful" or primary treatment compared to GnRH analogues or surgical options. * **B. Ectopic Pregnancy:** Mifepristone is **ineffective** here because progesterone receptors are often absent or poorly developed in the fallopian tubes. The medical treatment of choice for ectopic pregnancy is **Methotrexate**. * **C. Threatened Abortion:** Mifepristone is contraindicated. Since it is an anti-progestin, it would induce or complete an abortion rather than treat a "threatened" one, where the goal is to maintain the pregnancy. * **D. Molar Pregnancy:** It is highly effective for cervical priming before suction evacuation, reducing the induction-to-evacuation interval and minimizing blood loss. **High-Yield NEET-PG Pearls:** 1. **Mechanism:** Competitive Progesterone Antagonist (also blocks Glucocorticoid receptors at high doses). 2. **Medical Abortion Regimen:** 200 mg Mifepristone (oral) followed by 800 mcg Misoprostol (vaginal/buccal) 24–48 hours later (effective up to 9–10 weeks). 3. **Cushing’s Syndrome:** Mifepristone is FDA-approved for hyperglycemia secondary to endogenous Cushing’s (due to its anti-glucocorticoid action). 4. **Emergency Contraception:** Can be used as a single dose (10–25 mg) within 72 hours of intercourse.

Question 259: Sulfonylurea drugs produce hypoglycemia due to all the following mechanisms except?

A. Increases release of insulin from islet tissue
B. Increases biosynthesis of insulin in islet tissues (Correct Answer)
C. Increases number of insulin receptors
D. Sensitization of cells of islets to glucose

Explanation: **Explanation:** Sulfonylureas (SUs) are oral hypoglycemic agents that primarily act as **insulin secretagogues**. Their mechanism of action is centered on the release of pre-formed insulin rather than the production of new insulin. **1. Why Option B is the correct answer:** Sulfonylureas do **not** increase the biosynthesis (synthesis) of insulin. They act by binding to the **SUR1 subunit** of the ATP-sensitive $K^+$ channels on the pancreatic $\beta$-cell membrane. This leads to channel closure, membrane depolarization, $Ca^{2+}$ influx, and the subsequent exocytosis of **pre-stored insulin granules**. Since they trigger the release of what is already made, they do not stimulate the genetic or ribosomal machinery to synthesize more insulin. **2. Analysis of incorrect options:** * **Option A:** This is the primary mechanism. By closing $K_{ATP}$ channels, SUs directly trigger the release of insulin. * **Option C:** Chronic administration of SUs is known to have "extrapancreatic effects," which include increasing the number of insulin receptors on target tissues (like muscle and fat) and improving insulin sensitivity. * **Option D:** SUs "prime" the $\beta$-cells, making them more responsive to the natural glycemic stimulus (glucose), thereby enhancing glucose-mediated insulin secretion. **Clinical Pearls for NEET-PG:** * **First Generation SUs:** Tolbutamide, Chlorpropamide (associated with Disulfiram-like reactions and SIADH). * **Second Generation SUs:** Glibenclamide, Glipizide, Glimepiride (more potent). * **Side Effects:** Hypoglycemia (most common) and weight gain. * **Safety:** Glipizide is preferred in patients with mild renal impairment as it is primarily metabolized in the liver.

Question 260: Arrange the following insulins in order of their duration of action, from shortest to longest?

A. Degludec < NPH < Detemir < Glargine
B. NPH < Detemir < Glargine < Degludec (Correct Answer)
C. Glargine < NPH < Degludec < Detemir
D. Detemir < Degludec < NPH < Glargine

Explanation: **Explanation:** The duration of action of insulin preparations is determined by their chemical modifications, which affect their absorption from the subcutaneous site into the systemic circulation [1]. **1. Why Option B is Correct:** The correct sequence from shortest to longest duration is: **NPH < Detemir < Glargine < Degludec.** * **NPH (Neutral Protamine Hagedorn):** An intermediate-acting insulin. It is complexed with protamine and zinc, resulting in a duration of **12–18 hours** [2]. * **Detemir:** A long-acting analog with a fatty acid chain that promotes albumin binding. Its duration is dose-dependent, typically lasting **18–20 hours** [2]. * **Glargine (U-100):** Forms microprecipitates at physiological pH, providing a "peakless" profile for approximately **24 hours** [1]. * **Degludec:** An ultra-long-acting analog that forms multi-hexamers in subcutaneous tissue. It has a half-life of 25 hours and a duration of action exceeding **42 hours**. **2. Why Other Options are Incorrect:** * **Option A & C:** Incorrectly place NPH after long-acting analogs. NPH always has a shorter duration than the "basal" analogs (Glargine/Detemir). * **Option D:** Incorrectly suggests Detemir is shorter than NPH and Glargine is longer than Degludec. Degludec is currently the longest-acting insulin available. **3. High-Yield Clinical Pearls for NEET-PG:** * **Rapid-acting (Shortest duration):** Lispro, Aspart, Glulisine (Duration: 3–5 hours) [2]. * **Peakless Insulins:** Glargine and Degludec are preferred for basal coverage because they lack a distinct peak, significantly reducing the risk of **nocturnal hypoglycemia**. * **Mixing:** NPH can be mixed with regular insulin, but **Glargine/Detemir should not be mixed** in the same syringe with other insulins due to their acidic pH [1]. * **Degludec Advantage:** It offers the lowest intra-patient variability and a flexible dosing schedule.

Practice by Chapter

Hypothalamic and Pituitary Hormones

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Thyroid Drugs and Antithyroid Agents

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Insulin and Oral Hypoglycemic Agents

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Adrenocorticosteroids

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Sex Hormones: Estrogens and Progestins

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Androgens and Anabolic Steroids

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Hormonal Contraceptives

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Drugs Affecting Calcium Metabolism

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Drugs for Osteoporosis

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Pharmacological Management of Obesity

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