Endocrine Pharmacology Practice Questions

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

NPH < Detemir < Glargine < Degludec. **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.

Q: Which of the following is NOT true regarding GnRH analogues?

First-line management of menorrhagia. The correct answer is **D (First-line management of menorrhagia)**. While GnRH analogues (e.g., Leuprolide, Goserelin, Nafarelin) are effective in reducing menstrual blood flow by inducing a hypoestrogenic state, they are **not** first-line treatments. First-line management for menorrhagia typically includes NSAIDs, Tranexamic acid, or hormonal contraceptives (OCPs/LNG-IUS). GnRH analogues are reserved for short-term use (usually <6 months) or as a bridge to surgery due to their significant side-effect profile [2]. **Analysis of other options:** * **A. Precocious Puberty:** Continuous administration of GnRH analogues desensitizes the pituitary GnRH receptors (downregulation), suppressing the pituitary-gonadal axis [1], [2]. This makes them the **gold standard** for treating central precocious puberty. * **B. Osteoporosis:** Chronic use leads to a "pseudomenopause" state. Low estrogen levels increase osteoclast activity, leading to decreased bone mineral density and osteoporosis. This is why "add-back therapy" (low-dose estrogen/progestin) is often used. * **C. IVF:** In controlled ovarian hyperstimulation, GnRH analogues are used to suppress the endogenous LH surge, preventing premature ovulation before oocyte retrieval. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Pulsatile GnRH stimulates FSH/LH; **Continuous** GnRH inhibits FSH/LH (Downregulation) [1], [2]. * **Flare Phenomenon:** Initial administration causes a transient rise in gonadotropins [2]. In prostate cancer patients, this can cause a "bone pain flare," often prevented by co-administering Flutamide. * **Other Indications:** Endometriosis, uterine fibroids (to shrink size pre-operatively), and advanced prostate cancer [2].

Q: Insulin acts on which type of receptor?

Tyrosine kinase receptor. **Explanation:** **1. Why Tyrosine Kinase Receptor is Correct:** Insulin acts via a specific type of **Enzyme-linked receptor** known as the **Receptor Tyrosine Kinase (RTK)**. The insulin receptor is a heterotetramer consisting of two extracellular alpha subunits (binding site) and two transmembrane beta subunits. Upon insulin binding, the beta subunits undergo **autophosphorylation**, which activates the intrinsic tyrosine kinase activity. This triggers a signaling cascade involving **Insulin Receptor Substrates (IRS 1-4)** and the **PI3K/Akt pathway**, leading to the translocation of **GLUT-4** transporters to the cell membrane, facilitating glucose uptake. **2. Why Other Options are Incorrect:** * **Gs receptor (G-protein coupled):** These act via the Adenylyl Cyclase-cAMP pathway. Examples include Glucagon and Beta-adrenergic receptors. Insulin does not use G-proteins. * **Nuclear receptor:** These are intracellular receptors for lipid-soluble hormones like Steroids, Thyroid hormones, and Vitamin D. Insulin is a peptide hormone and cannot cross the lipid bilayer; it must act on surface receptors. * **Ligand-gated receptor:** These are ion channels that open in response to a neurotransmitter (e.g., Nicotinic ACh receptors). Insulin signaling involves enzymatic phosphorylation, not direct ion flux. **Clinical Pearls for NEET-PG:** * **GLUT-4** is the only insulin-dependent glucose transporter, found primarily in **skeletal muscle and adipose tissue**. * The **MAP Kinase pathway** is the other major pathway activated by insulin, responsible for its **growth-promoting and mitogenic effects**. * **Downregulation** of these receptors or defects in the IRS signaling leads to **Insulin Resistance** (Type 2 Diabetes). * Other hormones using Tyrosine Kinase: **IGF-1, EGF, and PDGF.**

Q: Ergometrine is not used for the initiation of labour because:

It causes fetal hypoxia.. **Explanation:** The primary goal during the initiation of labor is to mimic natural uterine contractions, which are rhythmic and followed by periods of relaxation. These relaxation phases are crucial for maintaining uteroplacental blood flow and fetal oxygenation. **Why Option B is Correct:** Ergometrine (an ergot alkaloid) induces **tetanic or sustained uterine contractions** with high basal tone. Unlike oxytocin, it does not allow for adequate uterine relaxation between contractions. This continuous compression of the intramyometrial blood vessels severely compromises blood flow to the placenta, leading to **fetal hypoxia and distress**. Therefore, its use is strictly contraindicated before the delivery of the fetus. **Analysis of Incorrect Options:** * **Option A:** Ergometrine actually has a rapid onset of action (1–5 minutes depending on the route), making it effective for emergency management of postpartum hemorrhage (PPH). * **Option C:** While ergometrine can cause vasoconstriction and increase blood pressure (making it contraindicated in pre-eclampsia/eclampsia), this is a maternal side effect and not the primary reason it is avoided for labor induction. * **Option D:** Ergometrine does have partial agonist activity at D2 receptors in the CTZ, causing nausea and vomiting, but this is a manageable side effect and not a contraindication for labor initiation. **High-Yield NEET-PG Pearls:** * **Drug of Choice (DOC) for Induction of Labor:** Oxytocin (due to its physiological, rhythmic contractions). * **DOC for Postpartum Hemorrhage (PPH):** Oxytocin (prophylaxis); Ergometrine or Carboprost (treatment). * **Contraindications for Ergometrine:** Pregnancy (before delivery), Hypertension, Preeclampsia, and Peripheral Vascular Disease. * **Mechanism:** Acts on 5-HT2 and alpha-adrenergic receptors in the myometrium.

Q: Monotherapy with which of the following antidiabetic drugs can cause hypoglycemia?

Gliclazide. **Explanation:** The risk of hypoglycemia with antidiabetic monotherapy depends on whether the drug’s mechanism is **insulin-independent** (euglycemic) or **insulin-secretagogue** (insulin-releasing). **1. Why Gliclazide is Correct:** Gliclazide is a **Second-Generation Sulfonylurea**. It works by binding to the SUR1 subunit of the ATP-sensitive K⁺ channels in pancreatic beta cells. This causes channel closure, depolarization, and a subsequent influx of calcium, leading to the **exocytosis of insulin regardless of blood glucose levels**. Because it forces insulin release even when blood sugar is normal, it can cause significant hypoglycemia. **2. Why Other Options are Incorrect:** * **Metformin (Biguanide):** It is an "insulin sensitizer." It primarily decreases hepatic gluconeogenesis and improves peripheral glucose uptake. It does not stimulate insulin secretion; hence, it is considered a **euglycemic** agent and does not cause hypoglycemia when used alone. * **Pioglitazone (Thiazolidinedione):** It acts as a PPAR-γ agonist, increasing insulin sensitivity in adipose and muscle tissue. Like Metformin, it does not increase insulin secretion from the pancreas, making the risk of monotherapy-induced hypoglycemia negligible. **High-Yield Clinical Pearls for NEET-PG:** * **Highest Risk:** Among sulfonylureas, **Glibenclamide** (long-acting) has the highest risk of hypoglycemia, while **Gliclazide** has a relatively lower risk due to its shorter half-life and reversible binding. * **Weight Gain:** Drugs that cause hypoglycemia (Sulfonylureas, Meglitinides, Insulin) typically also cause weight gain. * **Safe in Renal Failure:** Among sulfonylureas, **Gliquidone** is primarily excreted in bile, making it safer in renal impairment. * **Other Hypoglycemic Classes:** **Meglitinides** (Repaglinide) also act as secretagogues and can cause hypoglycemia.

Q: What is the mechanism of action of Exenatide?

GLP-1 Analogue. **Exenatide** is a synthetic version of exendin-4, a peptide originally found in the saliva of the Gila monster [2]. It functions as a **GLP-1 (Glucagon-Like Peptide-1) Receptor Agonist (Analogue)** [1, 2]. GLP-1 is an "incretin" hormone that stimulates glucose-dependent insulin secretion from pancreatic beta cells, suppresses inappropriate glucagon secretion, slows gastric emptying, and increases satiety [1, 2]. **Analysis of Options:** * **A. SGLT-2 Inhibitors:** These drugs (e.g., Dapagliflozin, Empagliflozin) act on the proximal convoluted tubule of the kidney to inhibit glucose reabsorption, leading to glucosuria. * **C. DPP-4 Inhibitors:** These drugs (e.g., Sitagliptin, Vildagliptin) prevent the breakdown of *endogenous* GLP-1 by inhibiting the enzyme Dipeptidyl Peptidase-4. While they share the incretin pathway, they are oral drugs, whereas Exenatide is an injectable analogue [1]. * **D. AMP Kinase Inhibitors:** This is the primary mechanism of **Metformin** (a Biguanide), which activates AMP-activated protein kinase (AMPK) to reduce hepatic gluconeogenesis and improve peripheral insulin sensitivity. **High-Yield Clinical Pearls for NEET-PG:** * **Weight Loss:** Unlike sulfonylureas and insulin, GLP-1 analogues cause significant weight loss, making them ideal for obese diabetic patients [2]. * **Route:** Exenatide is administered **subcutaneously** [1, 2]. * **Adverse Effects:** The most common side effect is nausea/vomiting. A rare but serious association is **acute pancreatitis** [2]. It is contraindicated in patients with a history of Medullary Thyroid Carcinoma (MTC) or MEN-2 syndrome. * **Cardiovascular Benefit:** Liraglutide (another GLP-1 analogue) is specifically noted for reducing major adverse cardiovascular events (MACE).

Q: A patient with benign prostatic hyperplasia is to be treated. Which of the following drugs would be most useful in this condition?

Finasteride. **Explanation:** **Finasteride** is the correct answer because it is a selective **5-alpha reductase inhibitor**. In the prostate, this enzyme converts testosterone into **Dihydrotestosterone (DHT)**, which is the primary androgen responsible for prostatic cell proliferation. By inhibiting this conversion, Finasteride reduces the size of the prostate gland (mechanical obstruction), improves urinary flow, and decreases the risk of acute urinary retention. **Analysis of Incorrect Options:** * **Cyproterone acetate:** A steroid with anti-androgenic and progestogenic activity. It blocks androgen receptors and inhibits gonadotropin secretion. It is primarily used for prostate cancer and hirsutism, but its side effect profile (hepatotoxicity) makes it unsuitable for BPH. * **Danazol:** A synthetic steroid that inhibits gonadotropin release. It is used in endometriosis and hereditary angioedema. It has weak androgenic properties, which would be counterproductive in BPH. * **Bicalutamide:** A potent non-steroidal pure androgen receptor antagonist. While it blocks DHT action, it is reserved for the treatment of **Metastatic Prostate Cancer** rather than BPH. **NEET-PG High-Yield Pearls:** * **Finasteride vs. Dutasteride:** Finasteride inhibits Type II 5-alpha reductase, while Dutasteride inhibits both Type I and Type II. * **Clinical Lag:** Unlike alpha-blockers (e.g., Tamsulosin), which work within days, 5-alpha reductase inhibitors take **6–12 months** to significantly reduce prostate volume. * **Other Uses:** Finasteride is also FDA-approved for **Male Pattern Baldness (Androgenetic Alopecia)** at lower doses (1mg). * **PSA Levels:** These drugs can decrease serum PSA levels by approximately 50%; this must be accounted for when screening for prostate cancer.

Q: Which of the following is used for medical adrenalectomy?

All of the above. **Explanation:** The term **"Medical Adrenalectomy"** refers to the use of pharmacological agents to inhibit the synthesis of adrenal steroids (cortisol, aldosterone, and androgens) as an alternative to surgical removal of the gland. This is typically indicated in Cushing’s syndrome (pre-operatively or in inoperable cases) and certain adrenal carcinomas. **Why "All of the above" is correct:** All three listed drugs act as **adrenocortical inhibitors** by blocking specific enzymes in the steroidogenesis pathway: * **Aminoglutethimide:** It inhibits the enzyme **cholesterol side-chain cleavage (CYP11A1)**, which converts cholesterol to pregnenolone. By blocking the very first step of steroid synthesis, it effectively shuts down the production of all adrenal steroids. * **Ketoconazole:** At high doses, this antifungal inhibits several enzymes, primarily **17α-hydroxylase** and **11β-hydroxylase**. It is often the first-line medical treatment for Cushing’s syndrome due to its efficacy. * **Metyrapone:** It is a selective inhibitor of **11β-hydroxylase**, the final step in cortisol synthesis. It is unique because it can be used to test pituitary ACTH reserve. **High-Yield Clinical Pearls for NEET-PG:** 1. **Metyrapone** is the only adrenal inhibitor that can be used during **pregnancy**. 2. **Ketoconazole** is known for causing **hepatotoxicity** and inhibiting androgen synthesis (leading to gynecomastia in males). 3. **Mitotane** is another agent used for medical adrenalectomy; it is specifically **adrenolytic** (causes permanent destruction of adrenocortical cells) and is used primarily in adrenal carcinoma. 4. **Etomidate** (an IV anesthetic) can also inhibit 11β-hydroxylase and is used in severe, acute hypercortisolemia.

Question 1

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

Accepted Answer

NPH < Detemir < Glargine < Degludec

Answer

Degludec < NPH < Detemir < Glargine

Answer

Glargine < NPH < Degludec < Detemir

Answer

Detemir < Degludec < NPH < Glargine

Question 2

Which of the following is NOT true regarding GnRH analogues?

Accepted Answer

First-line management of menorrhagia

Answer

Drug of choice for precocious puberty

Answer

Side effect is osteoporosis

Answer

Can be used for controlled ovarian hyperstimulation for IVF

Question 3

Insulin acts on which type of receptor?

Accepted Answer

Tyrosine kinase receptor

Answer

Gs receptor

Answer

Nuclear receptor

Answer

Ligand gated receptor

Question 4

Ergometrine is not used for the initiation of labour because:

Accepted Answer

It causes fetal hypoxia.

Answer

It has a slow onset of action.

Answer

It increases blood pressure.

Answer

It acts on D2 receptors to cause vomiting.

Question 5

A 72-year-old man presents with a 10-year history of increasing difficulty with urination, characterized by nocturia, urgency with small urine volumes, and hesitancy in starting and stopping micturition. Physical examination reveals an enlarged, non-tender prostate, approximately twice its normal size. His serum prostate-specific antigen (PSA) level was 6 ng/mL one year ago and remains unchanged. Which of the following drugs is most likely to be effective in treating this patient's condition?

Accepted Answer

Finasteride

Answer

Estrogen

Answer

Mitoxantrone

Answer

Nitrofurantoin

Question 6

Monotherapy with which of the following antidiabetic drugs can cause hypoglycemia?

Accepted Answer

Gliclazide

Answer

Metformin

Answer

Pioglitazone

Answer

All of the above

Question 7

Which of the following is NOT a side effect of steroids?

Accepted Answer

Hypoglycemia

Answer

Hypertension

Answer

Psychosis

Answer

Growth retardation

Question 8

What is the mechanism of action of Exenatide?

Accepted Answer

GLP-1 Analogue

Answer

SGLT inhibitor

Answer

DPP4 inhibitor

Answer

AMP kinase inhibitor

Question 9

A patient with benign prostatic hyperplasia is to be treated. Which of the following drugs would be most useful in this condition?

Accepted Answer

Finasteride

Answer

Cyproterone acetate

Answer

Danazol

Answer

Bicalutamide

Question 10

Which of the following is used for medical adrenalectomy?

Accepted Answer

All of the above

Answer

Metyrapone

Answer

Ketoconazole

Answer

Aminoglutethimide

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

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