Endocrine Pharmacology Practice Questions

Q: A pregnant female is taking carbimazole. Which of the following is NOT seen in the neonate?

Cleft lip/palate. **Explanation:** The question tests your knowledge of the teratogenic effects of anti-thyroid drugs. Carbimazole (a prodrug of Methimazole) is associated with a specific pattern of malformations known as **Methimazole Embryopathy**. **Why Cleft Lip/Palate is the correct answer:** Cleft lip and palate are **not** part of the classic Methimazole Embryopathy. While they are common congenital anomalies, they are not specifically linked to carbimazole exposure. In contrast, Propylthiouracil (PTU) is generally preferred in the first trimester because it has a lower risk of causing the specific structural defects associated with carbimazole. **Analysis of Incorrect Options:** * **Choanal Atresia (A) & Scalp Defects (B):** These are hallmark features of Methimazole Embryopathy. Scalp defects specifically refer to **Aplasia Cutis Congenita** (localized absence of skin, usually on the scalp). Other features include esophageal atresia and facial dysmorphism. * **Fetal Goiter (D):** Both Carbimazole and PTU cross the placenta and can inhibit the fetal thyroid gland. This leads to an increase in fetal TSH, resulting in fetal goiter and potential hypothyroidism. **High-Yield NEET-PG Pearls:** 1. **Drug of Choice:** PTU is preferred in the **1st trimester** (due to carbimazole teratogenicity). Carbimazole/Methimazole is preferred in the **2nd and 3rd trimesters** (due to PTU-induced maternal hepatotoxicity). 2. **Aplasia Cutis:** If you see "scalp defect" and "anti-thyroid drug" in a clinical stem, think Carbimazole/Methimazole. 3. **Mechanism:** Both drugs act by inhibiting the enzyme **Thyroid Peroxidase**, blocking the organification of iodine.

Q: Bisphosphonates act by which of the following mechanisms?

Decreasing osteoclast-mediated resorption of bone. **Explanation:** **Mechanism of Action (Why C is correct):** Bisphosphonates are synthetic analogs of pyrophosphate that have a high affinity for hydroxyapatite crystals in the bone. They primarily act by **inhibiting osteoclast-mediated bone resorption**. * **Simple Bisphosphonates (e.g., Etidronate):** Are metabolized into non-functional ATP analogs that induce osteoclast apoptosis. * **Nitrogen-containing Bisphosphonates (e.g., Alendronate, Zoledronate):** Inhibit the enzyme **farnesyl pyrophosphate (FPP) synthase** in the mevalonate pathway. This prevents the prenylation of GTP-binding proteins (like Rho and Ras) necessary for osteoclast survival and their "ruffled border" formation, leading to reduced bone resorption. **Analysis of Incorrect Options:** * **Options A & B:** Bisphosphonates do not stimulate osteoblasts or increase osteoid formation/mineralization. In fact, high doses of older bisphosphonates (Etidronate) can actually *impair* mineralization. Drugs that increase bone formation (anabolic agents) include Teriparatide. * **Option D:** Bisphosphonates do not directly affect the parathyroid gland. However, by decreasing bone resorption, they may cause a transient compensatory *increase* in PTH due to a slight drop in serum calcium. **High-Yield NEET-PG Pearls:** * **Drug of Choice:** Bisphosphonates are the first-line treatment for **Postmenopausal Osteoporosis** and **Paget’s Disease**. * **Administration:** Oral bisphosphonates (Alendronate) must be taken on an empty stomach with a full glass of water, and the patient must remain upright for 30 minutes to prevent **erosive esophagitis**. * **Adverse Effects:** Osteonecrosis of the Jaw (ONJ) and atypical subtrochanteric fractures (with long-term use). * **Potency:** Zoledronate is the most potent bisphosphonate and is administered intravenously once yearly.

Q: Which drug decreases the efficacy of testosterone?

Ketoconazole. **Explanation** The correct answer is **Ketoconazole**. **Mechanism of Action (Why it is correct):** Ketoconazole is a broad-spectrum imidazole antifungal that acts as a potent inhibitor of steroid synthesis. It inhibits the enzyme **17,20-lyase** (and to a lesser extent, CYP11A1/side-chain cleavage enzyme), which are essential steps in the conversion of cholesterol to androgens. By blocking these enzymes in both the testes and the adrenal glands, it significantly reduces testosterone production. Additionally, at high doses, it can displace testosterone from sex hormone-binding globulin (SHBG), further altering its efficacy. **Analysis of Incorrect Options:** * **Isoniazid (A):** While Isoniazid is a CYP450 inhibitor, it does not have a clinically significant effect on the steroidogenic pathways or the efficacy of testosterone. Its primary side effects are peripheral neuropathy and hepatotoxicity. * **Rifampicin (C):** Rifampicin is a potent **enzyme inducer**. While it can increase the metabolism of many steroid hormones (like oral contraceptives), it does not directly decrease the efficacy of testosterone in the same targeted, inhibitory manner as Ketoconazole. In fact, it often leads to a compensatory rise in LH and testosterone levels. **Clinical Pearls for NEET-PG:** * **Anti-androgenic side effects:** Due to testosterone inhibition, Ketoconazole can cause **gynecomastia**, decreased libido, and erectile dysfunction in men. * **Clinical Use:** Because of its ability to inhibit steroidogenesis, high-dose Ketoconazole is sometimes used off-label to treat **Cushing’s syndrome** and advanced **prostate cancer**. * **Other Drugs causing Gynecomastia (Mnemonic: DISCO):** **D**igoxin, **I**soniazid (rarely), **S**pironolactone, **C**imetidine, **O**estrogens/Ketoconazole.

Q: Which of the following is true of biguanides?

Cause little or no hypoglycemia. **Explanation:** Biguanides, primarily **Metformin**, are the first-line pharmacological agents for Type 2 Diabetes Mellitus. Their primary mechanism of action is the activation of **AMP-activated protein kinase (AMPK)**, which leads to increased insulin sensitivity and decreased hepatic glucose production. **1. Why Option A is correct:** Metformin is classified as an **"euglycemic"** agent rather than a hypoglycemic one. Unlike sulfonylureas, it does not stimulate insulin secretion from the pancreas. Instead, it works by improving the utilization of existing insulin and suppressing glucose production. Therefore, when used as monotherapy, it carries a negligible risk of hypoglycemia. **2. Why the other options are incorrect:** * **Option B:** Stimulating pancreatic beta cells is the mechanism of **Sulfonylureas** and **Meglitinides**. Metformin’s action is independent of beta-cell function. * **Option C:** Metformin is **not metabolized** in the body. It is excreted unchanged by the kidneys via tubular secretion. This is why it is contraindicated in renal failure (CrCl < 30 ml/min) due to the risk of accumulation. * **Option D:** Metformin **inhibits** hepatic gluconeogenesis (the synthesis of glucose from non-carbohydrate sources) and glycogenolysis, thereby lowering fasting blood glucose levels. **NEET-PG High-Yield Pearls:** * **Side Effects:** The most common side effects are GI-related (diarrhea, abdominal pain). The most serious, though rare, is **Lactic Acidosis**. * **Weight Neutrality:** Metformin is often associated with modest weight loss, making it ideal for obese diabetic patients. * **Vitamin Deficiency:** Long-term use can lead to **Vitamin B12 deficiency** due to interference with its absorption in the terminal ileum. * **Other Uses:** It is also used in Polycystic Ovarian Syndrome (PCOS) to improve insulin resistance and induce ovulation.

Q: Alendronate acts by:

Inhibiting osteoclasts. **Mechanism of Action** Alendronate is a **Bisphosphonate**, a class of drugs that are structural analogs of pyrophosphate. These drugs have a high affinity for hydroxyapatite crystals in the bone. When osteoclasts begin to resorb bone, they ingest the bisphosphonates. Once inside the cell, Alendronate inhibits the enzyme **Farnesyl Pyrophosphate (FPP) Synthase** in the mevalonate pathway. This prevents the prenylation of GTP-binding proteins (like Rho, Rac, and Rab) essential for osteoclast function, leading to the loss of the "ruffled border," inactivation, and eventually **apoptosis of osteoclasts**. **Analysis of Options** * **Option A (Correct):** By inducing osteoclast apoptosis and decreasing their bone-resorbing activity, Alendronate effectively increases bone mineral density. * **Option B & C (Incorrect):** Alendronate does not inhibit osteoblasts. In fact, by reducing bone resorption, it indirectly allows osteoblastic bone formation to exceed resorption in the short term, though long-term use leads to a coupled decrease in overall bone turnover. **NEET-PG High-Yield Pearls** * **Administration:** Must be taken on an empty stomach with a full glass of water, and the patient must remain upright for 30 minutes to prevent **erosive esophagitis**. * **Side Effects:** Atypical femur fractures and **Osteonecrosis of the Jaw (ONJ)** are rare but high-yield complications associated with long-term use. * **Drug of Choice:** Bisphosphonates are the first-line treatment for **Postmenopausal Osteoporosis** and **Paget’s disease**. * **Potency:** Alendronate is a second-generation (nitrogen-containing) bisphosphonate, which is significantly more potent than first-generation agents like Etidronate.

Q: In which of the following diseases are corticosteroids indicated?

Collagen vascular diseases. **Explanation:** **1. Why Collagen Vascular Diseases is Correct:** Corticosteroids are potent anti-inflammatory and immunosuppressive agents. They work by inhibiting phospholipase A2 (decreasing prostaglandins and leukotrienes) and suppressing the activation of T-cells and macrophages. **Collagen vascular diseases** (e.g., Systemic Lupus Erythematosus, Polyarteritis Nodosa, Dermatomyositis) are autoimmune conditions characterized by systemic inflammation. Steroids are the mainstay of treatment here to induce remission and prevent organ damage. **2. Why the Other Options are Incorrect:** * **Osteoporosis:** Corticosteroids are a major *cause* of secondary osteoporosis. They inhibit osteoblast activity, decrease intestinal calcium absorption, and increase renal calcium excretion. * **Peptic Ulcer:** Steroids are generally contraindicated or used with extreme caution in peptic ulcer disease. They inhibit protective prostaglandins in the gastric mucosa and can mask the symptoms of perforation, leading to "silent peritonitis." * **Tuberculosis (TB):** Since steroids suppress the immune system, they can lead to the reactivation of latent TB or worsen an active infection. They are only used in specific TB cases (like TB meningitis or pericarditis) alongside strict antitubercular therapy (ATT) to reduce inflammatory complications. **3. High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Steroids are the DOC for acute exacerbations of bronchial asthma and replacement therapy in Addison’s disease. * **Side Effect Profile:** Remember the mnemonic **CUSHINGOID** (Cataracts, Ulcers, Skin thinning, Hypertension/Hirsutism, Immunosuppression, Necrosis of femoral head, Glucose elevation, Osteoporosis, Impaired wound healing, Depression/Psychosis). * **Withdrawal:** Long-term steroid therapy must never be stopped abruptly due to the risk of **Acute Adrenal Insufficiency** (secondary to HPA axis suppression).

Q: Which of the following drug formulations is known to be hepatotoxic?

17 alpha methyl testosterone. **Explanation:** The correct answer is **17 alpha methyl testosterone**. **1. Why 17 alpha methyl testosterone is Hepatotoxic:** Testosterone, in its natural form, undergoes rapid first-pass metabolism in the liver, making it ineffective when taken orally. To overcome this, the molecule is modified by adding an alkyl group at the C-17 position (17-α alkylation). While this modification makes the drug orally bioavailable, it significantly increases the risk of **cholestatic jaundice** and serious liver conditions like **peliosis hepatis** (blood-filled cysts in the liver) and hepatic adenomas. **2. Why other options are incorrect:** * **Transdermal patches (A) and Intranasal (C):** These routes bypass the first-pass metabolism of the liver. They deliver testosterone directly into the systemic circulation, avoiding the high hepatic concentrations associated with oral alkylated steroids. * **Injectable Testosterone Undecanoate (D):** This is a testosterone ester. Esters are typically administered intramuscularly in an oil base. They are slowly released into the blood and hydrolyzed to natural testosterone, which does not possess the hepatotoxic profile of 17-α alkylated derivatives. **3. NEET-PG High-Yield Pearls:** * **Hepatotoxicity Rule:** Always associate **17-α alkylated steroids** (e.g., Methyltestosterone, Oxandrolone, Danazol, Stanozolol) with liver toxicity. * **Peliosis Hepatis:** A classic "buzzword" for complications arising from long-term anabolic steroid use. * **Clinical Use:** Due to hepatotoxicity, methyltestosterone is rarely used in modern clinical practice, replaced by safer transdermal or injectable esters. * **Side Effects:** Beyond hepatotoxicity, watch for erythrocytosis (increased hematocrit), azoospermia, and premature epiphyseal closure in children.

Q: Which of the following statements about glipizide compared to chlorpropamide is true?

Glipizide is more potent than chlorpropamide.. **Explanation:** Sulfonylureas are classified into first and second generations. This question compares **Chlorpropamide** (1st generation) and **Glipizide** (2nd generation). **1. Why Option A is Correct:** Glipizide is a second-generation sulfonylurea. Second-generation agents are significantly **more potent** than first-generation agents on a milligram-to-milligram basis. While chlorpropamide is used in doses of 100–500 mg, glipizide is effective at much lower doses (5–20 mg). Potency refers to the amount of drug required to produce a specific effect, not the clinical efficacy. **2. Why the Other Options are Incorrect:** * **Option B:** Chlorpropamide is the **longest-acting** sulfonylurea (half-life ~32 hours; duration up to 60 hours). Glipizide has a short half-life (~3 hours) and a shorter duration of action, making it safer in elderly patients. * **Option C:** All sulfonylureas act by stimulating insulin release from pancreatic beta cells (via blocking $K_{ATP}$ channels). Therefore, they **all** lower blood sugar in both diabetic and non-diabetic subjects. * **Option D:** Because chlorpropamide has an exceptionally long duration of action and is excreted renally, it is actually **more prone** to causing prolonged, severe hypoglycemia, especially in the elderly or those with renal impairment. **High-Yield Clinical Pearls for NEET-PG:** * **Disulfiram-like reaction:** Most commonly associated with Chlorpropamide. * **SIADH/Dilutional Hyponatremia:** A unique side effect of Chlorpropamide (it increases ADH action). * **Glipizide:** Preferred in patients with mild renal impairment because it is primarily metabolized by the liver to inactive metabolites. * **Mechanism:** Sulfonylureas bind to the **SUR1 subunit** of the ATP-sensitive $K^+$ channel.

Q: What is the most common side effect of mifepristone?

Diarrhea. **Explanation:** Mifepristone is a competitive progesterone receptor antagonist used primarily for medical termination of pregnancy (MTP) and the management of Cushing’s syndrome. **Why Diarrhea is the correct answer:** The most common side effects of mifepristone are gastrointestinal in nature. While mifepristone itself can cause nausea and vomiting, it is frequently administered in a regimen with **Misoprostol** (a PGE1 analog) for MTP. Misoprostol significantly increases intestinal motility and secretions, making **diarrhea** the most frequent and characteristic side effect reported by patients undergoing this treatment protocol. Even when used as monotherapy, GI upset remains the primary complaint. **Analysis of Incorrect Options:** * **A. Fever:** While a mild thermogenic effect or transient chills can occur (especially when combined with prostaglandins), it is less frequent than gastrointestinal symptoms. * **B. Headache:** This is a known side effect but occurs in a smaller percentage of patients compared to the nearly universal occurrence of GI distress. * **C. Rash:** Skin reactions are rare idiosyncratic responses and are not considered a common or expected side effect of the drug. **NEET-PG High-Yield Pearls:** * **Mechanism of Action:** Competitive antagonist at both Progesterone (PR) and Glucocorticoid (GR) receptors. * **MTP Protocol:** Usually 200 mg Mifepristone orally followed by 400–800 mcg Misoprostol (vaginal/sublingual/oral) 24–48 hours later. * **Other Uses:** Management of hyperglycemia in Cushing’s syndrome (due to GR antagonism) and as an emergency contraceptive. * **Contraindication:** Ectopic pregnancy (it is ineffective as it acts primarily on the decidua).

Question 1

A pregnant female is taking carbimazole. Which of the following is NOT seen in the neonate?

Accepted Answer

Cleft lip/palate

Answer

Choanal atresia

Answer

Scalp defects

Answer

Fetal goiter

Question 2

Bisphosphonates act by which of the following mechanisms?

Accepted Answer

Decreasing osteoclast-mediated resorption of bone

Answer

Increasing osteoid formation

Answer

Increasing the mineralization of osteoid

Answer

Decreasing parathyroid hormone secretion

Question 3

Which drug decreases the efficacy of testosterone?

Accepted Answer

Ketoconazole

Answer

Isoniazid

Answer

Rifampicin

Answer

None

Question 4

A 40-year-old woman presents with a 2-month history of chest pain on exertion. Her medical history includes pneumonia one month prior, with Streptococcus pneumoniae identified in her sputum. On physical examination, her body mass index is 35. Initial random blood glucose was 132 mg/dL. Subsequent fasting blood glucose values were 120 mg/dL and 122 mg/dL. An oral glucose tolerance test revealed a blood glucose of 240 mg/dL two hours after a 75-g glucose load. She was prescribed an oral thiazolidinedione (TZD) drug. After two months of therapy, her fasting blood glucose decreased to 90 mg/dL. The beneficial effect of TZD in this patient is most likely related to which of the following processes?

Accepted Answer

Activation of PPAR-gamma nuclear receptor in adipocytes

Answer

Decreased production of insulin autoantibodies

Answer

Greater density of insulin receptors in adipocytes

Answer

Increased half-life of circulating plasma insulin

Question 5

Which of the following is true of biguanides?

Accepted Answer

Cause little or no hypoglycemia

Answer

Stimulates pancreatic beta cells

Answer

Completely metabolized

Answer

Promotes hepatic gluconeogenesis

Question 6

Alendronate acts by:

Accepted Answer

Inhibiting osteoclasts

Answer

Inhibiting osteoblasts

Answer

Inhibiting both osteoclasts and osteoblasts

Answer

None of the above

Question 7

In which of the following diseases are corticosteroids indicated?

Accepted Answer

Collagen vascular diseases

Answer

Osteoporosis

Answer

Peptic ulcer

Answer

Tuberculosis

Question 8

Which of the following drug formulations is known to be hepatotoxic?

Accepted Answer

17 alpha methyl testosterone

Answer

Transdermal testosterone patch

Answer

Intranasal testosterone

Answer

Injectable testosterone undecanoate

Question 9

Which of the following statements about glipizide compared to chlorpropamide is true?

Accepted Answer

Glipizide is more potent than chlorpropamide.

Answer

Glipizide is longer acting than chlorpropamide.

Answer

Glipizide does not lower blood sugar in nondiabetic subjects, while chlorpropamide does.

Answer

Glipizide is less prone to cause a hypoglycemic reaction than chlorpropamide.

Question 10

What is the most common side effect of mifepristone?

Accepted Answer

Diarrhea

Answer

Fever

Answer

Headache

Answer

Rash

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

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