Endocrine Pharmacology — MCQs

Endocrine Pharmacology Indian Medical PG Practice Questions and MCQs

Question 61: Dapagliflozin is indicated for which of the following conditions?

A. Type 1 diabetes
B. Breast cancer
C. Type 2 diabetes (Correct Answer)
D. Bladder cancer

Explanation: **Explanation:** **Dapagliflozin** is a potent, reversible, and selective inhibitor of the **Sodium-Glucose Co-transporter 2 (SGLT2)**. 1. **Why Type 2 Diabetes (T2DM) is Correct:** SGLT2 is primarily located in the proximal convoluted tubule (PCT) of the kidney and is responsible for ~90% of glucose reabsorption. By inhibiting this transporter, Dapagliflozin reduces the renal threshold for glucose and promotes **glucosuria**. This insulin-independent mechanism effectively lowers blood glucose levels in patients with T2DM. 2. **Why Other Options are Incorrect:** * **Type 1 Diabetes:** SGLT2 inhibitors are not currently FDA-approved for T1DM due to a significantly increased risk of **Euglycemic Diabetic Ketoacidosis (eDKA)**. * **Breast Cancer:** There is no therapeutic indication for Dapagliflozin in breast cancer. * **Bladder Cancer:** This is actually a potential **contraindication/concern**. Early clinical trials suggested a slight numerical increase in bladder cancer cases with Dapagliflozin; therefore, it is generally avoided in patients with active or a history of bladder cancer. 3. **High-Yield Clinical Pearls for NEET-PG:** * **Cardio-Renal Protection:** Beyond glycemic control, SGLT2 inhibitors (Dapagliflozin, Empagliflozin) are now first-line for **Heart Failure (HFrEF)** and **Chronic Kidney Disease (CKD)**, regardless of diabetes status. * **Side Effects:** The most common side effects are **Genital Mycotic Infections** (e.g., Vulvovaginal candidiasis) and Urinary Tract Infections (UTIs) due to the high glucose content in urine. * **Weight Loss:** They promote weight loss (via calorie loss through urine) and a mild reduction in blood pressure (osmotic diuresis). * **Mnemonic:** SGLT2 inhibitors end in the suffix **"-gliflozin"** (think: *Glucose-Flowing-in-Urine*).

Question 62: Which of the following drugs can be safely prescribed in pregnancy?

A. Warfarin
B. ACE inhibitors
C. Heparin (Correct Answer)
D. Beta-blockers

Explanation: **Explanation:** The primary factor determining drug safety in pregnancy is the ability of a drug to cross the placental barrier. **Why Heparin is the Correct Answer:** Heparin (both Unfractionated Heparin and Low Molecular Weight Heparin like Enoxaparin) is a large, polar molecule with a high molecular weight. Due to these properties, it **does not cross the placenta** and therefore lacks teratogenic potential. It is the anticoagulant of choice for treating or preventing thromboembolism during pregnancy. **Why the Other Options are Incorrect:** * **Warfarin (Option A):** It is a small molecule that easily crosses the placenta. It is highly teratogenic, causing **Fetal Warfarin Syndrome** (nasal hypoplasia, stippled epiphyses, and CNS defects), especially when used in the first trimester. * **ACE Inhibitors (Option B):** These are contraindicated, particularly in the 2nd and 3rd trimesters. They cause **fetal renal dysgenesis**, oligohydramnios, and skull hypoplasia. * **Beta-blockers (Option D):** While some (like Labetalol) are used for gestational hypertension, they are generally associated with risks like **fetal growth restriction (IUGR)**, neonatal hypoglycemia, and bradycardia. They are not as "universally safe" as Heparin in the context of systemic drug categories. **High-Yield Clinical Pearls for NEET-PG:** * **LMWH** is preferred over UFH in pregnancy due to a lower risk of Heparin-Induced Thrombocytopenia (HIT) and osteoporosis. * **Safe antihypertensives in pregnancy:** "Better Mother Love Hyper": **B**eta-blockers (Labetalol), **M**ethyldopa (Drug of choice), **L**evamlodipine/Nifedipine, **H**ydralazine. * **Teratogenic mnemonic:** "WACE" (Warfarin, ACEi, Carbamazepine, Ethanol) are high-priority drugs to avoid.

Question 63: Which corticosteroid has the maximum sodium-retaining potential?

A. Dexamethasone
B. Prednisolone
C. Aldosterone (Correct Answer)
D. Betamethasone

Explanation: **Explanation:** The question tests the understanding of the relative mineralocorticoid (sodium-retaining) versus glucocorticoid (anti-inflammatory) potencies of various steroids. **1. Why Aldosterone is Correct:** Aldosterone is the primary endogenous **mineralocorticoid** synthesized in the zona glomerulosa of the adrenal cortex. Its physiological role is to promote sodium and water reabsorption and potassium excretion in the distal convoluted tubule and collecting ducts of the kidney. On a comparative scale, if Cortisol has a sodium-retaining potency of 1, Aldosterone has a potency of **3000**, making it the most potent sodium-retaining steroid among the options. **2. Why the Other Options are Incorrect:** * **Dexamethasone & Betamethasone:** These are long-acting, highly potent **pure glucocorticoids**. They have a sodium-retaining potency of **zero**. This makes them ideal for conditions where fluid retention must be avoided (e.g., cerebral edema). * **Prednisolone:** This is an intermediate-acting glucocorticoid with mild mineralocorticoid activity (potency of **0.8** relative to Cortisol). While it causes some sodium retention, it is significantly weaker than Aldosterone. **3. High-Yield Clinical Pearls for NEET-PG:** * **Fludrocortisone:** This is the most potent *synthetic* mineralocorticoid (potency ~125-250) and is the drug of choice for replacement therapy in Addison’s disease. * **Potency Ratio:** Dexamethasone is the most potent anti-inflammatory steroid (25-30 times more than cortisol) but has no mineralocorticoid effect. * **DOCA (Desoxycorticosterone acetate):** Another pure mineralocorticoid, but unlike Aldosterone, it lacks glucocorticoid activity entirely. * **Rule of Thumb:** As glucocorticoid potency increases in synthetic steroids (Prednisolone → Betamethasone), mineralocorticoid activity typically decreases.

Question 64: Which of the following is an anabolic steroid?

A. Methyltestosterone
B. Fluoxymesterone
C. Nandrolone (Correct Answer)
D. Danazole

Explanation: **Explanation:** **Nandrolone** is the correct answer because it is a synthetic derivative of testosterone specifically designed to have a **high anabolic-to-androgenic ratio**. While all androgens possess both effects, anabolic steroids like Nandrolone (Deca-Durabolin) and Oxandrolone are modified to maximize protein synthesis and muscle growth (anabolic) while minimizing virilizing effects (androgenic). Clinically, Nandrolone is used to treat negative nitrogen balance in catabolic states, severe cachexia, and certain types of anemia (due to erythropoietic stimulation). **Analysis of Incorrect Options:** * **Methyltestosterone & Fluoxymesterone (Options A & B):** These are orally active **androgens**. While they have anabolic properties, they are primarily classified as systemic androgens used for male hypogonadism. They have a higher risk of hepatotoxicity (cholestatic jaundice) due to their 17-α alkylation. * **Danazol (Option D):** This is a synthetic steroid with weak androgenic properties but is primarily used for its **anti-gonadotropic** effects. It suppresses the pituitary-ovarian axis and is the drug of choice for Hereditary Angioedema and is used in endometriosis and fibrocystic breast disease. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Anabolic steroids bind to the same cytoplasmic androgen receptors as testosterone but are often resistant to conversion by 5-α reductase. * **Side Effects:** Hepatic tumors (adenomas), cholestatic jaundice, azoospermia, and premature closure of epiphyses in children. * **Stanozolol:** Another frequently tested anabolic steroid used in hereditary angioedema. * **Abuse:** Often misused by athletes; can lead to "Roid Rage" (psychosis/aggression) and severe acne.

Question 65: Danazol is useful in the treatment of all the following conditions EXCEPT?

A. Hirsutism (Correct Answer)
B. Endometriosis
C. Dysfunctional uterine bleeding (DUB)
D. Leiomyoma

Explanation: **Explanation** Danazol is a synthetic steroid and a derivative of ethisterone. Its mechanism of action involves the suppression of the pituitary-ovarian axis by inhibiting the mid-cycle surge of LH and FSH. It also directly inhibits several enzymes involved in steroidogenesis and possesses weak androgenic properties. **Why Hirsutism is the correct answer:** Danazol is **not** used to treat hirsutism; in fact, it **causes** hirsutism as a side effect [1]. Because Danazol has inherent androgenic activity, it leads to virilizing side effects such as acne, weight gain, deepening of the voice, and increased facial hair (hirsutism) [1]. For treating hirsutism, anti-androgens like Spironolactone or Cyproterone acetate are preferred [2]. **Analysis of other options:** * **Endometriosis:** Danazol was historically the "gold standard" for endometriosis [1]. It creates a "pseudomenopause" by suppressing estrogen, leading to the atrophy of ectopic endometrial tissue. * **Dysfunctional Uterine Bleeding (DUB):** By inducing endometrial atrophy and inhibiting gonadotropins, Danazol effectively reduces menstrual blood loss. * **Leiomyoma (Uterine Fibroids):** Danazol can reduce the size of fibroids by creating a hypoestrogenic environment, although GnRH agonists are now more commonly used for this purpose. **High-Yield Clinical Pearls for NEET-PG:** * **Hematological Use:** Danazol is a drug of choice for **Hereditary Angioneurotic Edema** (it increases the synthesis of the C1 esterase inhibitor) [1]. * **Other Uses:** It is used in **Fibrocystic breast disease** (breast dysplasia) [1] and **Immune Thrombocytopenic Purpura (ITP)**. * **Contraindication:** It is strictly contraindicated in pregnancy due to the risk of virilization of a female fetus [3]. **Note on consolidation:** Although Reference [2] and [3] are from the same book, they are from different chapter segments (719 vs 707) representing distinct thematic units in the source material, so they are cited individually.

Question 66: Which of the following anti-thyroid drugs is considered safe in pregnancy?

A. Carbimazole
B. Iodine
C. Propylthiouracil (Correct Answer)
D. Methimazole

Explanation: **Explanation:** The management of hyperthyroidism (Graves' disease) in pregnancy requires careful selection of anti-thyroid drugs (ATDs) to balance maternal health and fetal safety. **Why Propylthiouracil (PTU) is the correct answer:** PTU is the drug of choice during the **first trimester** of pregnancy. The primary reason is its high protein-binding capacity and lower lipid solubility compared to other ATDs, which results in **less placental transfer**. More importantly, PTU is not associated with the specific congenital malformations (embryopathy) linked to Methimazole. **Analysis of Incorrect Options:** * **Methimazole (Option D):** While more potent, it is avoided in the first trimester because it is a known teratogen. It is associated with **Methimazole Embryopathy**, which includes **Aplasia Cutis** (congenital skin defects on the scalp), choanal atresia, and esophageal atresia. * **Carbimazole (Option A):** This is a prodrug that is rapidly converted to Methimazole in the body. Therefore, it carries the same teratogenic risks as Methimazole. * **Iodine (Option B):** Radioactive iodine (I-131) is strictly **contraindicated** in pregnancy as it crosses the placenta and can destroy the fetal thyroid gland, leading to permanent hypothyroidism. **High-Yield Clinical Pearls for NEET-PG:** 1. **Trimester Switch:** Current guidelines recommend **PTU for the 1st trimester** (to avoid organogenesis defects) and switching to **Methimazole for the 2nd and 3rd trimesters** (to avoid PTU-induced maternal hepatotoxicity). 2. **Mechanism:** Both drugs inhibit *Thyroid Peroxidase*, but PTU has the additional advantage of inhibiting the peripheral conversion of T4 to T3. 3. **Breastfeeding:** Both PTU and Methimazole are considered safe during lactation in moderate doses.

Question 67: A patient with severe shoulder pain resulting from inflammation is not responding to treatment with naproxen. Treatment with oral dexamethasone was initiated. What is the basis for the glucocorticoid being more effective as an anti-inflammatory agent?

A. Glucocorticoids inhibit both prostaglandin production and inflammatory cells. (Correct Answer)
B. Glucocorticoids inhibit the biosynthesis of both COX-1 and COX-2.
C. Glucocorticoids will reduce the edema in the inflamed area.
D. Glucocorticoids are more potent inhibitors of cyclooxygenase than naproxen.

Explanation: ### Explanation **1. Why Option A is Correct:** Glucocorticoids (like dexamethasone) are superior to NSAIDs (like naproxen) because they act at multiple levels of the inflammatory cascade. While NSAIDs only inhibit the cyclooxygenase (COX) enzymes to reduce prostaglandin synthesis, glucocorticoids: * **Inhibit Phospholipase A2:** By inducing **Annexin-1 (Lipocortin-1)**, they block the release of arachidonic acid, thereby inhibiting both the **Prostaglandin (COX)** and **Leukotriene (LOX)** pathways. * **Inhibit Inflammatory Cells:** They suppress the recruitment and activation of neutrophils, macrophages, and T-lymphocytes. * **Genomic Effects:** They downregulate the expression of pro-inflammatory cytokines (IL-1, IL-6, TNF-α) and adhesion molecules. **2. Why Other Options are Incorrect:** * **Option B:** Glucocorticoids do not primarily work by inhibiting the "biosynthesis" of COX-1; their main action on COX is the **repression of COX-2 gene expression**. * **Option C:** While glucocorticoids do reduce edema (by decreasing capillary permeability), this is a *result* of their anti-inflammatory action, not the comprehensive *basis* for why they are more effective than NSAIDs. * **Option D:** Glucocorticoids do not bind to or inhibit the cyclooxygenase enzyme directly; they work upstream (Phospholipase A2) and at the genetic level. **3. NEET-PG High-Yield Pearls:** * **Mechanism:** Glucocorticoids bind to cytosolic receptors, translocate to the nucleus, and bind to **Glucocorticoid Response Elements (GRE)**. * **Hematological Effects:** Glucocorticoids cause **"Steroid-induced Leukocytosis"** (increase in Neutrophils due to decreased margination) but **decrease** Lymphocytes, Eosinophils, Monocytes, and Basophils (mnemonic: **"LEMB"** goes down). * **Potency:** Dexamethasone is a long-acting steroid with high anti-inflammatory potency and **zero** mineralocorticoid activity, making it ideal for inflammatory conditions without causing fluid retention.

Question 68: Which antithyroid drug is contraindicated in pregnancy?

A. Propylthiouracil
B. Radioactive Iodine (131I) (Correct Answer)
C. Methimazole
D. Carbimazole

Explanation: **Explanation:** **1. Why Radioactive Iodine (131I) is the Correct Answer:** Radioactive Iodine (131I) is **absolutely contraindicated** in pregnancy (FDA Category X). Iodine-131 crosses the placenta and is concentrated by the fetal thyroid gland after the 10th–12th week of gestation. This leads to permanent **fetal thyroid ablation**, resulting in congenital hypothyroidism, mental retardation, and an increased risk of childhood malignancies. A pregnancy test is mandatory before administering 131I to any woman of reproductive age. **2. Analysis of Incorrect Options:** * **Propylthiouracil (PTU):** This is the **drug of choice in the 1st trimester**. It is preferred because it is more highly protein-bound than Methimazole, leading to less placental transfer. It also avoids the specific teratogenic risks associated with Methimazole. * **Methimazole (MMI):** While generally avoided in the 1st trimester due to risks of **Aplasia Cutis** (congenital skin defects) and **Choanal/Esophageal atresia**, it is the **preferred drug in the 2nd and 3rd trimesters** because PTU carries a higher risk of maternal hepatotoxicity. * **Carbimazole:** This is a prodrug of Methimazole. It carries the same teratogenic profile as Methimazole and is avoided in early pregnancy. **3. NEET-PG High-Yield Pearls:** * **1st Trimester Choice:** Propylthiouracil (PTU). * **2nd/3rd Trimester Choice:** Methimazole (MMI). * **Mechanism of PTU:** Inhibits Thyroid Peroxidase (TPO) AND peripheral conversion of T4 to T3 (MMI does not inhibit peripheral conversion). * **Breastfeeding:** Both PTU and MMI are considered safe in moderate doses, though MMI is often preferred here to avoid maternal liver issues. * **Thyroid Storm:** PTU is preferred due to its dual action (inhibiting synthesis and peripheral conversion).

Question 69: All of the following statements regarding T3 (Tri-iodothyronine) are true EXCEPT?

A. Half-life of T3 is only a few hours.
B. Only 20% of the total T3 is produced by the thyroid.
C. T3 is usually given as 100 mg once daily. (Correct Answer)
D. T3 is the active form of the hormone and is produced in the periphery by conversion from T4.

Explanation: **Explanation:** The correct answer is **C** because it contains two significant pharmacological errors: the **dosage unit** and the **frequency**. T3 (Liothyronine) is highly potent; the standard replacement dose is measured in **micrograms (mcg)**, not milligrams (mg). Furthermore, due to its short half-life, it requires **multiple daily dosing** (2–3 times a day) rather than once-daily administration to maintain stable plasma levels. **Analysis of other options:** * **Option A (True):** T3 has a very short half-life of approximately **18–24 hours** (compared to 7 days for T4). This necessitates frequent dosing and makes it less ideal for routine maintenance therapy. * **Option B (True):** The thyroid gland primarily secretes T4. Only about **20%** of circulating T3 is secreted directly by the thyroid; the remaining **80%** is generated via peripheral deiodination. * **Option D (True):** T3 is the **physiologically active** form. It has a 3–5 times higher affinity for nuclear thyroid receptors than T4. T4 acts largely as a pro-hormone that undergoes peripheral conversion by the enzyme **5'-deiodinase**. **High-Yield NEET-PG Pearls:** * **Drug of Choice:** Levothyroxine (T4) is the drug of choice for hypothyroidism due to its long half-life, low cost, and stable serum levels. * **Myxedema Coma:** While IV Levothyroxine is standard, **IV Liothyronine (T3)** is preferred in some protocols for faster onset of action in life-threatening cases. * **Deiodination Inhibitors:** Drugs like **Propylthiouracil (PTU), Propranolol, and Glucocorticoids** inhibit the peripheral conversion of T4 to T3, which is why they are used in managing Thyroid Storm.

Question 70: Which drug is used for the treatment of bleeding gastrointestinal varices?

A. Demeclocycline
B. Desmopressin
C. Terlipressin (Correct Answer)
D. Leuprolide

Explanation: **Explanation:** **Terlipressin** is the drug of choice for the management of acute bleeding esophageal varices. It is a synthetic analogue of Vasopressin (ADH) with a longer duration of action and a better safety profile. **Mechanism of Action:** Terlipressin acts primarily on **V1 receptors** located on vascular smooth muscle. Stimulation of these receptors causes potent **splanchnic vasoconstriction**. This reduces portal venous blood flow and lowers portal pressure, thereby allowing the variceal bleed to stop and facilitating endoscopic intervention. **Analysis of Incorrect Options:** * **A. Demeclocycline:** A tetracycline derivative that acts as an ADH antagonist at the V2 receptor. It is used in the treatment of SIADH, not for vasoconstriction. * **B. Desmopressin (dDAVP):** A selective **V2 receptor agonist**. It is used for Central Diabetes Insipidus, von Willebrand disease, and nocturnal enuresis. It lacks significant V1 activity and therefore does not cause the vasoconstriction required to treat varices. * **C. Leuprolide:** A GnRH agonist used in the treatment of prostate cancer, endometriosis, and precocious puberty. It has no effect on the vascular system or portal pressure. **High-Yield NEET-PG Pearls:** * **Drug of Choice:** Terlipressin is preferred over Vasopressin because it causes less systemic vasoconstriction (fewer cardiac side effects). * **Octreotide:** A somatostatin analogue often used as an alternative; it reduces portal pressure by inhibiting the release of vasodilator hormones like glucagon. * **Prophylaxis:** While Terlipressin treats *acute* bleeds, **Non-selective beta-blockers** (e.g., Propranolol, Nadolol) are used for the *primary prevention* of variceal bleeding.

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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