Endocrine Pharmacology — MCQs

Endocrine Pharmacology Indian Medical PG Practice Questions and MCQs

Question 531: True statements regarding octreotide are all of the following except:

A. Synthetic octapeptide
B. Used in variceal bleeding
C. Contraindicated in acromegaly (Correct Answer)
D. Useful in secretory diarrhea

Explanation: **Explanation:** Octreotide is a synthetic **somatostatin analogue** with a much longer half-life (approx. 1.5 hours) compared to natural somatostatin (approx. 2 minutes). It acts as a potent inhibitor of various physiological functions, particularly the secretion of growth hormone (GH) and various gastrointestinal hormones. **Why Option C is the Correct Answer (The False Statement):** Octreotide is **not contraindicated** in acromegaly; in fact, it is a **first-line medical treatment**. Acromegaly is caused by excessive GH secretion (usually from a pituitary adenoma). Octreotide binds to somatostatin receptors (SSTR-2 and SSTR-5) on the pituitary gland, effectively suppressing GH and IGF-1 levels. **Analysis of Other Options:** * **Option A (Synthetic octapeptide):** This is true. Octreotide consists of 8 amino acids, making it an octapeptide. * **Option B (Used in variceal bleeding):** This is true. It causes splanchnic vasoconstriction and reduces portal venous pressure, making it highly effective in managing acute esophageal variceal hemorrhage. * **Option D (Useful in secretory diarrhea):** This is true. By inhibiting the secretion of serotonin and other GI peptides, it is used to treat diarrhea associated with Carcinoid syndrome, VIPomas, and even refractory AIDS-related diarrhea. **High-Yield Clinical Pearls for NEET-PG:** * **Side Effects:** The most common side effect is **steatorrhea** (due to inhibition of pancreatic enzymes). Long-term use carries a high risk of **cholelithiasis** (gallstones) because it inhibits gallbladder contractility. * **Other Indications:** Used in the management of **Zollinger-Ellison Syndrome**, **Glucagonoma**, and **Insulinoma**. * **Administration:** Available as subcutaneous injections or long-acting release (LAR) formulations.

Question 532: Danazol is used for the following conditions except?

A. Endometriosis
B. Fibroadenosis of the breast
C. Delayed puberty (Correct Answer)
D. Gynaecomastia

Explanation: **Explanation:** **Danazol** is a synthetic ethisterone derivative with weak androgenic and anabolic properties. It acts as a "selective pituitary gonadotropin inhibitor" by suppressing the mid-cycle surge of LH and FSH. **Why "Delayed Puberty" is the Correct Answer:** Danazol is **contraindicated** in delayed puberty. Because it suppresses the hypothalamic-pituitary-gonadal (HPG) axis and inhibits gonadotropin release, it would further delay the onset of puberty. Furthermore, its androgenic nature can cause **premature epiphyseal closure**, leading to stunted height, which is detrimental in pediatric/adolescent populations. **Analysis of Incorrect Options:** * **Endometriosis:** Danazol is a classic (though now second-line) treatment. It creates a "pseudomenopause" by suppressing FSH/LH and directly inhibiting ovarian steroidogenic enzymes, leading to the atrophy of ectopic endometrial tissue. * **Fibroadenosis (Fibrocystic Breast Disease):** By reducing estrogenic stimulation and suppressing gonadotropins, Danazol effectively relieves pain and reduces nodularity in the breast. * **Gynaecomastia:** It is used to treat gynaecomastia by inhibiting the pituitary-testicular axis and reducing testicular estrogen production. **High-Yield Clinical Pearls for NEET-PG:** * **Hereditary Angioedema:** Danazol is a drug of choice for prophylaxis as it increases the hepatic synthesis of the **C1 esterase inhibitor** protein. * **Hematological use:** It is used in refractory Immune Thrombocytopenic Purpura (ITP). * **Side Effects:** Weight gain, acne, hirsutism, and deepening of voice (due to androgenic activity). It is strictly **contraindicated in pregnancy** (teratogenic; causes virilization of female fetuses).

Question 533: Oral contraceptives primarily act by which mechanism?

A. Increasing Luteinizing Hormone (LH)
B. Increasing Follicle-Stimulating Hormone (FSH)
C. Decreasing Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH) (Correct Answer)
D. Decreasing Adrenocorticotropic Hormone (ACTH) and Somatotropic Releasing Factor (SRF)

Explanation: **Explanation:** The primary mechanism of action of Combined Oral Contraceptive Pills (COCPs) is the **suppression of ovulation** through a negative feedback loop on the Hypothalamic-Pituitary-Ovarian (HPO) axis. 1. **Mechanism of the Correct Answer:** COCPs contain synthetic estrogen (usually Ethinylestradiol) and progestin. * **Estrogen** suppresses the release of **FSH** (Follicle-Stimulating Hormone) from the anterior pituitary, which prevents the recruitment and maturation of a dominant ovarian follicle. * **Progestin** suppresses the mid-cycle surge of **LH** (Luteinizing Hormone), which is essential for ovulation. By decreasing both FSH and LH, the pills prevent the physiological triggers required for the release of an egg. 2. **Why Incorrect Options are Wrong:** * **Options A & B:** Increasing LH or FSH would stimulate follicular development and trigger ovulation, which is the opposite of the desired contraceptive effect (this occurs with drugs like Clomiphene). * **Option D:** ACTH and SRF (Growth Hormone Releasing Factor) are involved in adrenal and growth functions, respectively. They have no direct role in the primary contraceptive mechanism of OCPs. **High-Yield Clinical Pearls for NEET-PG:** * **Secondary Mechanisms:** Progestins also cause thickening of the cervical mucus (preventing sperm penetration) and make the endometrium atrophic (preventing implantation). * **Progestin-Only Pills (POPs):** Their primary mechanism is thickening cervical mucus; they do not consistently suppress ovulation. * **Non-Contraceptive Benefits:** OCPs reduce the risk of **Ovarian and Endometrial cancers**, but may slightly increase the risk of Breast and Cervical cancers. * **Contraindication:** Absolute contraindication in smokers >35 years due to the risk of thromboembolism.

Question 534: Glucocorticoids have proved useful in the treatment of which of the following conditions?

A. Chemotherapy-induced vomiting (Correct Answer)
B. Hyperprolactinemia
C. Parkinson's disease
D. Type II diabetes

Explanation: **Explanation:** **Glucocorticoids (e.g., Dexamethasone)** are highly effective in managing **chemotherapy-induced nausea and vomiting (CINV)**. While the exact mechanism is not fully understood, it is believed they act by inhibiting prostaglandin synthesis in the hypothalamus, reducing peritumoral edema, and modulating serotonin (5-HT3) receptors. Dexamethasone is often used in combination with 5-HT3 antagonists (like Ondansetron) and NK1 receptor antagonists (like Aprepitant) to enhance their antiemetic efficacy, especially in highly emetogenic chemotherapy regimens. **Analysis of Incorrect Options:** * **B. Hyperprolactinemia:** This condition is treated with **Dopamine agonists** (e.g., Cabergoline, Bromocriptine) because dopamine naturally inhibits prolactin release. Glucocorticoids have no role here. * **C. Parkinson’s Disease:** This is a neurodegenerative disorder caused by dopamine deficiency. Treatment involves increasing dopamine levels (e.g., **Levodopa-Carbidopa**) or using dopamine agonists. Glucocorticoids do not cross the blood-brain barrier to affect the basal ganglia in this manner. * **D. Type II Diabetes:** Glucocorticoids are actually **contraindicated** or must be used with extreme caution in diabetes. They promote gluconeogenesis and decrease peripheral glucose uptake, leading to **hyperglycemia** and worsening of glycemic control. **High-Yield Clinical Pearls for NEET-PG:** * **Dexamethasone** is the preferred steroid for CINV due to its high potency and minimal mineralocorticoid activity. * Glucocorticoids are also used in **Cerebral Edema** (specifically vasogenic edema associated with tumors) and **Adrenal Insufficiency** (Addison’s disease). * **Side Effects:** Chronic use leads to Cushingoid features, osteoporosis, and increased susceptibility to infections.

Question 535: What is the half-life of intravenous oxytocin?

A. 1 minute
B. 3 minutes (Correct Answer)
C. 7 minutes
D. 9 minutes

Explanation: **Explanation:** **Correct Option: B (3 minutes)** Oxytocin is a peptide hormone synthesized in the hypothalamus and released by the posterior pituitary. When administered intravenously, it has a very **short half-life, typically ranging from 3 to 5 minutes**. This rapid clearance occurs because oxytocin is quickly degraded by the liver, kidneys, and the enzyme **oxytocinase** (aminopeptidase), which increases in concentration during pregnancy. This short half-life is clinically significant as it allows for precise titration during labor induction; if uterine hyperstimulation occurs, stopping the infusion leads to a rapid decline in plasma levels and cessation of effect. **Incorrect Options:** * **A (1 minute):** This is too short. While the onset of action is almost immediate, the metabolic degradation takes slightly longer. * **C & D (7 and 9 minutes):** These durations exceed the standard physiological and pharmacological half-life of oxytocin. By 7–9 minutes, several half-lives would have passed, and the plasma concentration would be significantly depleted. **High-Yield NEET-PG Pearls:** * **Mechanism:** Acts via G-protein coupled receptors (Gq) to increase intracellular calcium in uterine smooth muscle. * **Clinical Use:** Drug of choice for **Induction of Labor** and **Postpartum Hemorrhage (PPH)**. * **Side Effects:** At high doses, oxytocin has an **antidiuretic effect** (due to structural similarity to ADH), which can lead to water intoxication, hyponatremia, and seizures. * **Bolus Warning:** Rapid IV bolus can cause transient **hypotension** and reflex tachycardia. Always administer as a dilute infusion.

Question 536: Which of the following conditions is NOT an indication for bromocriptine?

A. Parkinsonism
B. Galactorrhea
C. Acromegaly
D. Hypothyroidism (Correct Answer)

Explanation: **Mechanism of Action:** Bromocriptine is a potent **Dopamine D2 receptor agonist** and a partial D1 antagonist. It acts by mimicking the inhibitory effects of dopamine in the brain and pituitary gland. **Explanation of the Correct Answer:** * **D. Hypothyroidism:** This is the correct answer because Bromocriptine has no role in treating thyroid deficiency. Hypothyroidism is managed with **Levothyroxine** (T4). In fact, dopamine agonists can suppress TSH secretion, which would be counterproductive in treating primary hypothyroidism. **Explanation of Incorrect Options:** * **A. Parkinsonism:** Bromocriptine is a first-generation ergot derivative used to treat Parkinson’s disease. By stimulating D2 receptors in the striatum, it compensates for the lack of endogenous dopamine. * **B. Galactorrhea:** Dopamine is the primary **Prolactin Inhibiting Factor (PIF)**. Bromocriptine inhibits prolactin release from the anterior pituitary, making it a first-line treatment for hyperprolactinemia, galactorrhea, and prolactinomas. * **C. Acromegaly:** While dopamine stimulates Growth Hormone (GH) in healthy individuals, it paradoxically **inhibits GH release** in patients with acromegaly. Although somatostatin analogues (Octreotide) are more effective, Bromocriptine is an adjuvant treatment option. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** While Bromocriptine is classic, **Cabergoline** is now preferred for hyperprolactinemia due to its higher efficacy, longer half-life (twice weekly dosing), and better side-effect profile. * **Other Indications:** Bromocriptine is also FDA-approved for **Type 2 Diabetes Mellitus** (quick-release formulation) to improve glycemic control via hypothalamic modulation. * **Side Effects:** Nausea, dizziness, and orthostatic hypotension. Long-term use of ergot derivatives is associated with **pulmonary/cardiac fibrosis**.

Question 537: Why are sulfonylureas shifted to insulin in pregnant patients?

A. Sulfonylureas cause pregnancy-induced hypertension.
B. Increased metabolic demands during pregnancy cannot be met by sulfonylureas alone.
C. Insulin does not cross the placenta. (Correct Answer)
D. Sulfonylureas deplete insulin from fetal pancreatic beta cells.

Explanation: **Explanation:** The primary goal in managing Gestational Diabetes Mellitus (GDM) or pre-existing diabetes in pregnancy is to maintain strict glycemic control while ensuring fetal safety. **Why Option C is Correct:** Insulin is a large protein molecule (molecular weight ~5800 Da). Due to its high molecular weight, it **does not cross the placental barrier**. This allows for precise control of maternal blood glucose without directly affecting fetal glucose metabolism or causing fetal hyperinsulinemia. Consequently, insulin is considered the "Gold Standard" for diabetes in pregnancy. **Analysis of Incorrect Options:** * **Option A:** Sulfonylureas are not a recognized cause of pregnancy-induced hypertension (PIH). PIH is primarily related to placental vascular dysfunction. * **Option B:** While metabolic demands increase during pregnancy, the shift is primarily due to **safety and teratogenicity concerns**, not just potency. Many oral hypoglycemic agents (OHAs) are avoided because they cross the placenta. * **Option D:** While first-generation sulfonylureas (like Chlorpropamide) were avoided due to risks of fetal hypoglycemia, they do not "deplete" fetal insulin. However, the risk of stimulating the fetal pancreas and causing neonatal hypoglycemia is a reason they are avoided. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Insulin is the first-line treatment for diabetes in pregnancy. * **Oral Hypoglycemics:** While **Metformin** and **Glibenclamide** (Glyburide) are sometimes used in specific clinical settings (Category B), they are generally second-line to insulin because they cross the placenta to varying degrees. * **Teratogenicity:** Most OHAs are avoided in the first trimester due to potential (though debated) teratogenic risks and the risk of prolonged neonatal hypoglycemia. * **Insulin Types:** Human insulin and rapid-acting analogs (Lispro, Aspart) are safe and commonly used in pregnancy.

Question 538: Which of the following statements is true about octreotide?

A. It stimulates growth hormone secretion.
B. It is useful in controlling secretory diarrhea. (Correct Answer)
C. It is active orally.
D. Its use is contraindicated in acromegaly.

Explanation: **Explanation:** Octreotide is a long-acting synthetic analog of **Somatostatin** (Growth Hormone Inhibiting Hormone). [1] It mimics the natural hormone but has a significantly longer half-life (approx. 1.5 hours vs. 2 minutes). [2] **Why Option B is correct:** Octreotide is highly effective in controlling **secretory diarrhea** associated with VIPomas, carcinoid syndrome, and HIV-related malabsorption. [2] It works by inhibiting the secretion of various gastrointestinal hormones (like VIP, serotonin, and gastrin), decreasing intestinal fluid/electrolyte secretion, and slowing gastrointestinal motility. [2] **Analysis of Incorrect Options:** * **Option A:** Octreotide **inhibits** (not stimulates) the secretion of Growth Hormone (GH), glucagon, insulin, and TSH. [1] * **Option C:** Octreotide is a peptide and is degraded by gastric enzymes; therefore, it is **not orally active**. It must be administered parenterally (Subcutaneous or Intravenous). [1], [2] * **Option D:** Acromegaly is a primary **indication** for octreotide, not a contraindication. [1], [3] It is used to reduce GH and IGF-1 levels when surgery or radiotherapy is insufficient. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice (DOC):** Octreotide is the DOC for the management of **acute variceal bleeding** (it causes splanchnic vasoconstriction) [3] and **acromegaly** (medical management). [1] * **Adverse Effects:** The most common side effect is **steatorrhea** (due to inhibition of pancreatic enzymes). [1] Long-term use carries a high risk of **gallstones (cholelithiasis)** because it inhibits cholecystokinin (CCK) release and gallbladder contraction. [1], [3] * **Other Uses:** It is used to treat dumping syndrome and "Zollinger-Ellison Syndrome" (refractory cases).

Question 539: Hyperprolactinemia is a side effect of which of the following medications?

A. Bromocriptine
B. Levodopa
C. Amantadine
D. Metoclopramide (Correct Answer)

Explanation: **Explanation:** The regulation of prolactin secretion is primarily under the **tonic inhibitory control of Dopamine** (also known as Prolactin Inhibiting Factor) acting on **D2 receptors** in the anterior pituitary. Any drug that blocks these D2 receptors or decreases dopamine levels will result in **Hyperprolactinemia**. **Why Metoclopramide is correct:** Metoclopramide is a potent **central D2 receptor antagonist** used as a prokinetic and antiemetic. By blocking D2 receptors in the pituitary, it removes the inhibitory influence of dopamine on lactotrophs, leading to increased prolactin secretion. This can clinically manifest as galactorrhea, amenorrhea, or gynecomastia. **Why the other options are incorrect:** * **Bromocriptine:** This is a **D2 receptor agonist**. It mimics dopamine and is actually the treatment of choice for hyperprolactinemia and prolactinomas. * **Levodopa:** A precursor to dopamine, it increases dopamine levels in the brain and systemic circulation, thereby **decreasing** prolactin levels. * **Amantadine:** This drug increases dopamine release and inhibits its reuptake. Like other dopaminergic agents, it tends to suppress rather than elevate prolactin. **High-Yield Clinical Pearls for NEET-PG:** * **Antipsychotics** (especially typicals like Haloperidol and atypicals like Risperidone) are the most common pharmacological cause of hyperprolactinemia. * **Tuberoinfundibular Pathway:** This is the specific dopaminergic pathway responsible for prolactin regulation. * **Other causes:** Methyldopa (depletes dopamine), Reserpine, and Verapamil (mechanism unclear but high-yield). * **Management:** If drug-induced, the offending agent should be stopped; if pathological (prolactinoma), **Cabergoline** is preferred over Bromocriptine due to higher efficacy and better tolerability.

Question 540: Which of the following is an oral incretin analogue?

A. Semaglutide (Correct Answer)
B. Dulaglutide
C. Exenatide
D. Liraglutide

Explanation: **Explanation:** Incretin analogues, specifically **GLP-1 (Glucagon-Like Peptide-1) receptor agonists**, are agents that mimic the action of endogenous incretins to stimulate insulin secretion, inhibit glucagon release, and delay gastric emptying. **Correct Answer: A. Semaglutide** Traditionally, GLP-1 analogues were exclusively injectable due to their peptide nature, which leads to degradation by gastric acid. However, **Semaglutide** is the first and only GLP-1 analogue available in an **oral formulation**. This was achieved by co-formulating the drug with an absorption enhancer called **SNAC** (Sodium N-salcaprozate), which protects it from proteolytic degradation in the stomach and facilitates transcellular absorption. **Incorrect Options:** * **B. Dulaglutide:** A long-acting GLP-1 analogue administered as a **once-weekly subcutaneous injection**. * **C. Exenatide:** The first GLP-1 analogue (derived from Gila monster saliva). It is available as a **twice-daily or once-weekly subcutaneous injection**. * **D. Liraglutide:** A long-acting GLP-1 analogue administered as a **once-daily subcutaneous injection**. It is also FDA-approved for weight management. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism of Action:** Glucose-dependent insulin secretion (low risk of hypoglycemia). * **Weight Effect:** Significant **weight loss** (useful in obese Type 2 Diabetics). * **Cardiovascular Benefit:** Liraglutide, Semaglutide, and Dulaglutide reduce the risk of major adverse cardiovascular events (MACE). * **Side Effects:** Nausea/vomiting (most common) and a theoretical risk of **Medullary Thyroid Carcinoma** and **Pancreatitis**. * **Contraindication:** Personal or family history of Multiple Endocrine Neoplasia (MEN) type 2.

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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