Which of the following is the most potent topical corticosteroid?
Which of the following reduces the efficacy of oral contraceptives?
What is the best drug for control of acute esophageal variceal bleeding?
What is the drug of choice for pheochromocytoma?
The best agent for increasing HDL cholesterol is?
All of the following are adverse effects of nicotinic acid except:
What is the mechanism of action of clofibrate in lipid metabolism?
Drug that binds bile acids in the intestine and prevents their return to liver via the enterohepatic circulation?
Which of the following is an antitussive opioid?
Drug of choice for familial hypercholesterolemia?
NEET-PG 2013 - Pharmacology NEET-PG Practice Questions and MCQs
Question 91: Which of the following is the most potent topical corticosteroid?
- A. Triamcinolone acetonide
- B. Hydrocortisone acetate
- C. Clobetasol propionate (Correct Answer)
- D. Betamethasone valerate
Explanation: ***Clobetasol propionate*** - **Clobetasol propionate** is recognized as one of the most potent **Class I topical corticosteroids**, used for severe inflammatory skin conditions. - Its high potency allows for effective suppression of severe inflammation and pruritus, but also carries a greater risk of **adverse effects** with prolonged use. *Triamcinolone acetonide* - **Triamcinolone acetonide** is a **medium-potency** topical corticosteroid (Class IV-V), less potent than clobetasol propionate. - It is commonly used for moderate inflammatory skin conditions, such as eczema and psoriasis, but not for severe cases requiring maximum potency. *Hydrocortisone acetate* - **Hydrocortisone acetate** is a **low-potency** topical corticosteroid (Class VII), making it the least potent option listed. - It's often used for mild inflammatory conditions, sensitive areas like the face, or for less severe conditions requiring minimal corticosteroid strength. *Betamethasone valerate* - **Betamethasone valerate** is a **medium-to-high potency** topical corticosteroid (Class III-V), placing it among stronger corticosteroids but still less potent than clobetasol propionate. - It is effective for moderate to severe inflammatory skin conditions but does not reach the highest level of potency demonstrated by clobetasol.
Question 92: Which of the following reduces the efficacy of oral contraceptives?
- A. Griseofulvin (Correct Answer)
- B. Disulfiram
- C. Erythromycin
- D. Cimetidine
Explanation: ***Griseofulvin*** - **Griseofulvin** is an antifungal agent known to induce liver enzymes, specifically the **cytochrome P450 system**. - Enzyme induction accelerates the metabolism and clearance of **oral contraceptives**, leading to lower plasma concentrations and reduced efficacy. *Erythromycin* - **Erythromycin** is a macrolide antibiotic that typically inhibits liver enzymes rather than inducing them. - While it can interfere with the metabolism of some drugs, it usually **increases** rather than decreases the plasma levels of co-administered medications, and is not known to reduce oral contraceptive efficacy. *Disulfiram* - **Disulfiram** is used to treat chronic alcoholism and inhibits aldehyde dehydrogenase. - It does not significantly interact with the metabolism of **oral contraceptives** via the cytochrome P450 system or other mechanisms that would reduce their efficacy. *Cimetidine* - **Cimetidine** is an H2 receptor antagonist that is known to inhibit cytochrome P450 enzymes. - This inhibition would likely **increase** the plasma concentration of drugs metabolized by these enzymes, such as oral contraceptives, rather than reducing their efficacy.
Question 93: What is the best drug for control of acute esophageal variceal bleeding?
- A. Vasopressin
- B. GnRH
- C. Octreotide (Correct Answer)
- D. Propranolol
Explanation: ***Octreotide*** - **Octreotide** is a somatostatin analog that causes **splanchnic vasoconstriction**, reducing portal venous inflow and pressure, which is crucial in controlling **esophageal variceal bleeding**. - Its mechanism involves inhibiting the release of **vasodilatory hormones** like glucagon, leading to a decrease in portal pressure without significant systemic side effects. *Vasopressin* - **Vasopressin** is a potent vasoconstrictor that can reduce portal pressure but has significant systemic side effects such as **myocardial ischemia** and **bowel ischemia** due to widespread vasoconstriction. - It is generally no longer considered the first-line pharmacological treatment for variceal bleeding due to its **adverse effect profile**. *GnRH* - **GnRH** (Gonadotropin-releasing hormone) plays a role in regulating the reproductive system by controlling the release of FSH and LH from the pituitary. - It has **no direct role** in the management or control of esophageal bleeding. *Propranolol* - **Propranolol** is a non-selective beta-blocker primarily used for **prophylaxis** of variceal bleeding by reducing portal pressure chronically. - It works by reducing cardiac output and causing splanchnic vasoconstriction, but it is **not used for acute control** of active bleeding.
Question 94: What is the drug of choice for pheochromocytoma?
- A. Propranolol
- B. Phenoxybenzamine (Correct Answer)
- C. Prazosin
- D. Nitroprusside
Explanation: ***Phenoxybenzamine*** - This is an **irreversible, non-selective alpha-adrenergic blocker**, which is the drug of choice for preparing patients for surgical removal of a pheochromocytoma. - It effectively controls **hypertension** by blocking the effects of catecholamines on blood vessels, preventing a hypertensive crisis during surgery. *Propranolol* - **Beta-blockers** like propranolol should **not be used as monotherapy** in pheochromocytoma because blocking beta-2 receptors without prior alpha blockade can lead to unopposed alpha-adrenergic vasoconstriction and precipitate a **hypertensive crisis**. - It can be added **after adequate alpha-blockade** to control tachycardia. *Prazosin* - Prazosin is a **reversible, selective alpha-1 adrenergic blocker**, which is not preferred over phenoxybenzamine due to its shorter duration of action and reversibility. - While it can lower blood pressure, its efficacy in preventing hypertensive crises during surgery for pheochromocytoma is **less robust** compared to phenoxybenzamine. *Nitroprusside* - Sodium nitroprusside is a **potent vasodilator** often used for **hypertensive emergencies**, but it is not the drug of choice for long-term management or preoperative preparation in pheochromocytoma. - Its use in pheochromocytoma is typically reserved for **acute hypertensive crises** when other agents are insufficient, rather than initial management.
Question 95: The best agent for increasing HDL cholesterol is?
- A. Statin
- B. Nicotinic acid (Correct Answer)
- C. Gugulipids
- D. Fibrates
Explanation: ***Nicotinic acid*** - **Nicotinic acid** (niacin) is known to significantly increase **high-density lipoprotein (HDL) cholesterol** levels by reducing its catabolism. - It also has beneficial effects on other lipid parameters, such as lowering **triglycerides** and **LDL cholesterol**. *Statin* - **Statins** (HMG-CoA reductase inhibitors) are highly effective at lowering **LDL cholesterol** and moderately lowering triglycerides. - While they can cause a modest increase in HDL cholesterol, their primary role is not HDL elevation. *Gugulipids* - **Gugulipids**, derived from the gum resin of the _Commiphora mukul_ tree, have been used in traditional medicine to lower cholesterol. - Evidence for their efficacy in significantly increasing HDL cholesterol is weak and not clinically recommended. *Fibrates* - **Fibrates** primarily work to lower **triglyceride levels** and can modestly increase HDL cholesterol. - Their effect on HDL is generally less pronounced compared to nicotinic acid.
Question 96: All of the following are adverse effects of nicotinic acid except:
- A. Liver dysfunction
- B. Vasodilation
- C. Hyperpigmentation
- D. Pancreatitis (Correct Answer)
Explanation: ***Pancreatitis*** - **Pancreatitis** is not a commonly reported adverse effect of nicotinic acid (niacin) therapy. - While other gastrointestinal side effects like nausea and vomiting can occur, pancreatic inflammation is not characteristic. *Vasodilation* - **Cutaneous flushing** and **vasodilation** are very common adverse effects of nicotinic acid, mediated by prostaglandin release. - This effect can cause a sensation of warmth, redness, and itching, especially at the start of therapy. *Liver dysfunction* - **Liver dysfunction**, including elevated liver enzymes and rare cases of **hepatotoxicity**, can occur with high doses of nicotinic acid. - Regular monitoring of liver function tests is recommended for patients on niacin therapy. *Hyperpigmentation* - **Hyperpigmentation**, particularly **acanthosis nigricans**, is a known cutaneous side effect of nicotinic acid. - This typically presents as dark, velvety patches on the skin, especially in skin fold areas.
Question 97: What is the mechanism of action of clofibrate in lipid metabolism?
- A. Inhibits lipolysis in adipose tissue.
- B. Inhibits HMG CoA reductase.
- C. Binds bile acids and bile salts in the small intestine.
- D. Increases lipoprotein lipase activity through PPAR alpha, leading to enhanced lipolysis of triglycerides. (Correct Answer)
Explanation: ***Increases lipoprotein lipase activity through PPAR alpha, leading to enhanced lipolysis of triglycerides.*** - Clofibrate, a **fibrat**e, acts as an agonist for **peroxisome proliferator-activated receptor alpha (PPAR-α)**. - Activation of PPAR-α leads to increased synthesis of **lipoprotein lipase (LPL)**, which enhances the breakdown of **triglycerides** in VLDL particles. *Inhibits lipolysis in adipose tissue.* - This mechanism is characteristic of **niacin (nicotinic acid)**, which reduces the release of free fatty acids from adipose tissue. - Clofibrate's primary action is not focused on inhibiting lipolysis in adipose tissue. *Inhibits HMG CoA reductase.* - This is the mechanism of action for **statins** (e.g., simvastatin, atorvastatin), which are used to reduce cholesterol synthesis. - Clofibrate does not directly inhibit HMG CoA reductase. *Binds bile acids and bile salts in the small intestine.* - This mechanism is characteristic of **bile acid sequestrants** (e.g., cholestyramine, colestipol). - These drugs prevent the reabsorption of bile acids, leading to increased cholesterol conversion to bile acids in the liver.
Question 98: Drug that binds bile acids in the intestine and prevents their return to liver via the enterohepatic circulation?
- A. Niacin
- B. Fenofibrate
- C. Cholestyramine (Correct Answer)
- D. Gugulipid
Explanation: ***Cholestyramine*** - **Cholestyramine** is a **bile acid-binding resin** that sequesters bile acids in the intestine, preventing their reabsorption. - This interruption of the **enterohepatic circulation** leads to increased synthesis of new bile acids from cholesterol in the liver, thus lowering plasma LDL cholesterol. *Niacin* - **Niacin (nicotinic acid)** reduces the hepatic synthesis and secretion of **VLDL**, which in turn lowers LDL and triglyceride levels. - It works primarily through mechanisms related to fat metabolism in the liver and adipose tissue, not direct bile acid binding in the intestine. *Fenofibrate* - **Fenofibrate** is a **PPAR-α agonist** that primarily reduces triglyceride levels by increasing fatty acid oxidation and lipoprotein lipase activity, and secondarily increases HDL. - Its main action is on lipid metabolism in the liver and peripheral tissues, not by binding bile acids in the gut. *Gugulipid* - **Gugulipid** is a phytosterol derived from the guggul tree, sometimes used in traditional medicine for cholesterol management. - Its purported mechanism involves increasing **bile acid excretion** and inhibiting cholesterol biosynthesis, but it does not directly bind bile acids in the same manner as resins like cholestyramine.
Question 99: Which of the following is an antitussive opioid?
- A. Pethidine
- B. Methadone
- C. Buprenorphine
- D. Ethylmorphine (Correct Answer)
Explanation: ***Ethylmorphine*** - **Ethylmorphine** (also known as dionin) is an opioid derivative with significant **antitussive properties**, meaning it suppresses coughing. - It works by acting on opioid receptors in the **medulla oblongata**, reducing the cough reflex. *Pethidine* - **Pethidine** (also known as meperidine) is a synthetic opioid primarily used for **moderate to severe pain relief**. - While it has some central nervous system effects, its main therapeutic use is as an **analgesic**, not an antitussive. *Methadone* - **Methadone** is a synthetic opioid used for treating **opioid dependence** and for **chronic severe pain**. - Its main application is in addiction treatment and pain management, not specifically as a cough suppressant. *Buprenorphine* - **Buprenorphine** is a **partial opioid agonist** used for pain management and **opioid dependence**. - It has a high affinity for opioid receptors but produces a limited effect, making it less likely to be used solely as an antitussive and more for its analgesic or anti-addictive properties.
Question 100: Drug of choice for familial hypercholesterolemia?
- A. Nicotinic acid
- B. Lovastatin (Correct Answer)
- C. Cholestyramine
- D. Gemfibrozil
Explanation: ***Lovastatin*** - **Statins** (HMG-CoA reductase inhibitors) are the **first-line therapy** for familial hypercholesterolemia as they effectively lower **LDL cholesterol** levels by inhibiting cholesterol synthesis [1]. - While other agents can be used adjunctively, statins like lovastatin are the cornerstone for managing this genetic condition [2]. *Nicotinic acid* - **Nicotinic acid** (niacin) primarily lowers **triglycerides** and increases **HDL cholesterol**, but it is less potent than statins for reducing LDL-C, especially in familial hypercholesterolemia [1]. - Its use is often limited by significant **side effects** like flushing. *Cholestyramine* - **Cholestyramine** is a **bile acid sequestrant** that binds to bile acids in the intestine, preventing their reabsorption and mildly lowering LDL cholesterol. - It is less effective than statins and often causes **gastrointestinal side effects** such as constipation and bloating. *Gemfibrozil* - **Gemfibrozil** is a **fibrate**, primarily used to lower **triglyceride levels** and increase HDL cholesterol. - It has minimal impact on LDL cholesterol compared to statins and is not the primary treatment for familial hypercholesterolemia [2].