Endocrine Pharmacology Practice Questions

Q: Prostaglandin derivatives are used in the following conditions, except:

Abortion. **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.

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

Increases biosynthesis of insulin in islet tissues. **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.

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).

Question 1

Prostaglandin derivatives are used in the following conditions, except:

Accepted Answer

Abortion

Answer

Cervical ripening

Question 2

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

Accepted Answer

Increases biosynthesis of insulin in islet tissues

Answer

Increases release of insulin from islet tissue

Answer

Increases number of insulin receptors

Answer

Sensitization of cells of islets to glucose

Question 3

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 4

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 5

Insulin acts on which type of receptor?

Accepted Answer

Tyrosine kinase receptor

Answer

Gs receptor

Answer

Nuclear receptor

Answer

Ligand gated receptor

Question 6

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 7

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 8

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

Accepted Answer

Gliclazide

Answer

Metformin

Answer

Pioglitazone

Answer

All of the above

Question 9

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

Accepted Answer

Hypoglycemia

Answer

Hypertension

Answer

Psychosis

Answer

Growth retardation

Question 10

What is the mechanism of action of Exenatide?

Accepted Answer

GLP-1 Analogue

Answer

SGLT inhibitor

Answer

DPP4 inhibitor

Answer

AMP kinase inhibitor

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

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