Analgesics and Anti-inflammatory Drugs — MCQs

Analgesics and Anti-inflammatory Drugs Indian Medical PG Practice Questions and MCQs

Question 321: Which of the following is not a DMARD in the treatment of rheumatoid arthritis?

A. Methotrexate
B. Leflunomide
C. Corticosteroids (Correct Answer)
D. Penicillamine

Explanation: **Explanation:** The core concept in treating Rheumatoid Arthritis (RA) is the distinction between drugs that provide symptomatic relief and those that modify the disease process. **Disease-Modifying Anti-Rheumatic Drugs (DMARDs)** are agents that slow down disease progression, prevent joint destruction, and reduce radiological damage. **Why Corticosteroids is the correct answer:** While corticosteroids (like Prednisolone) are potent anti-inflammatory agents used to provide rapid symptomatic relief and "bridge" the gap until DMARDs become effective, they are **not** classified as DMARDs. They do not fundamentally arrest the long-term progression of the disease or prevent joint deformity when used alone. Chronic use is also limited by significant systemic toxicity. **Analysis of incorrect options:** * **A. Methotrexate:** The "Gold Standard" and first-line DMARD. It acts by inhibiting dihydrofolate reductase and increasing adenosine levels, which suppresses inflammation and joint damage. * **B. Leflunomide:** A prodrug that inhibits the enzyme dihydroorotate dehydrogenase, leading to decreased pyrimidine synthesis. It is a potent DMARD often used as an alternative to Methotrexate. * **D. Penicillamine:** A conventional (synthetic) DMARD. Though rarely used today due to toxicity (like proteinuria and myasthenia-like syndrome), it historically belongs to the DMARD category. **High-Yield Clinical Pearls for NEET-PG:** * **Classification:** DMARDs are divided into **csDMARDs** (Conventional Synthetic: Methotrexate, Sulfasalazine, Hydroxychloroquine, Leflunomide) and **bDMARDs** (Biologicals: TNF-inhibitors like Etanercept, Infliximab). * **Fastest acting DMARD:** Sulfasalazine. * **Slowest acting DMARD:** Hydroxychloroquine (takes 3–6 months). * **Methotrexate Monitoring:** Requires supplementation with Folic acid to reduce GI and mucosal side effects. It is contraindicated in pregnancy (Teratogenic).

Question 322: Which drug is used for the treatment of acute gout?

A. Aspirin
B. Indomethacin (Correct Answer)
C. Febuxostat
D. Allopurinol

Explanation: **Explanation:** The primary goal in treating **acute gout** is to control pain and inflammation. **Indomethacin**, a potent Non-Steroidal Anti-inflammatory Drug (NSAID), is the traditional drug of choice for acute attacks. It works by inhibiting cyclooxygenase (COX) enzymes, thereby reducing the synthesis of prostaglandins that mediate pain and swelling in the joint. **Analysis of Options:** * **Indomethacin (Correct):** It is highly effective in terminating an acute gouty attack. Other NSAIDs like Naproxen or Diclofenac are also used, but Indomethacin remains the classic textbook answer. * **Aspirin (Incorrect):** Aspirin is contraindicated in gout. At low doses, it inhibits the tubular secretion of uric acid, leading to **hyperuricemia**, which can worsen or prolong an attack. * **Allopurinol & Febuxostat (Incorrect):** These are **hypouricemic agents** (Xanthine Oxidase Inhibitors) used for **chronic gout** (prophylaxis). They should never be started during an acute attack because a rapid drop in serum urate levels can cause the mobilization of urate crystals from tissues, paradoxically worsening the acute inflammation. **High-Yield Clinical Pearls for NEET-PG:** * **First-line for Acute Gout:** NSAIDs (e.g., Indomethacin) are first-line. If NSAIDs are contraindicated (e.g., peptic ulcer, renal failure), **Colchicine** or **Glucocorticoids** are used. * **Colchicine Mechanism:** It inhibits microtubule assembly by binding to tubulin, thereby preventing neutrophil migration to the joint. * **The "Wait" Rule:** Never start or stop Allopurinol during an acute attack. Wait 2–4 weeks after the attack has subsided before initiating urate-lowering therapy.

Question 323: What type of opioid receptor agonist is Buprenorphine?

A. Pure agonist
B. Pure antagonist
C. Partial agonist (Correct Answer)
D. None of the above

Explanation: **Buprenorphine** is classified as a **Partial Mu ($\\mu$) Opioid Receptor Agonist** and a **Kappa ($\\kappa$) Opioid Receptor Antagonist** [2]. 1. **Why Option C is correct:** As a partial agonist, buprenorphine has high affinity for the $\\mu$-receptor but low intrinsic activity (efficacy) [1]. This results in a **"Ceiling Effect"**—beyond a certain dose, increasing the amount of drug does not increase the analgesic effect or respiratory depression [1, 3]. This makes it safer in overdose compared to full agonists [1]. 2. **Why Option A is incorrect:** Pure agonists (e.g., Morphine, Fentanyl) have high intrinsic activity and no ceiling effect on respiratory depression. 3. **Why Option B is incorrect:** Pure antagonists (e.g., Naloxone, Naltrexone) bind to the receptor but produce no biological response; they are used to reverse opioid effects. **High-Yield Clinical Pearls for NEET-PG:** * **Opioid Substitution Therapy:** Due to its long duration of action and slow dissociation from $\\mu$-receptors, it is used in treating opioid dependence (detoxification and maintenance) [3]. * **Precipitated Withdrawal:** If given to a patient already dependent on a full agonist (like Heroin), buprenorphine can displace the full agonist and trigger withdrawal symptoms due to its lower intrinsic activity. * **Route:** It undergoes extensive first-pass metabolism, so it is typically administered **sublingually** or via transdermal patches [3]. * **Reversibility:** Because it binds so tightly to receptors, higher-than-normal doses of Naloxone are required to reverse its effects in case of toxicity [3].

Question 324: Naltrexone is:

A. Mu receptor agonist
B. Delta receptor agonist
C. Kappa receptor agonist
D. Mu receptor antagonist (Correct Answer)

Explanation: **Explanation:** **Naltrexone** is a potent, long-acting **pure opioid antagonist**. It works by competitively binding to opioid receptors with a very high affinity, thereby blocking the effects of endogenous and exogenous opioids. While it acts on Mu, Kappa, and Delta receptors, its primary clinical effect is mediated through the **antagonism of Mu (μ) receptors**. * **Why Option D is correct:** Naltrexone blocks the Mu receptor, preventing the euphoria and physical dependence associated with opioid use. Unlike Naloxone (which is used for acute overdose), Naltrexone has high oral bioavailability and a long half-life (approx. 10 hours), making it ideal for maintenance therapy. * **Why Options A, B, and C are incorrect:** Naltrexone does not activate (agonize) any opioid receptors. An agonist would produce morphine-like effects (analgesia, sedation, respiratory depression). Naltrexone specifically lacks intrinsic activity; it only occupies the receptor to prevent agonist binding. **Clinical Pearls for NEET-PG:** 1. **Indications:** Used for the **prevention of relapse** in detoxified opioid addicts and for **Alcohol Dependence** (it reduces alcohol craving by blocking the reward pathways mediated by endogenous opioids). 2. **Naltrexone vs. Naloxone:** Remember the mnemonic **"Nal-O-xone is for Overdose"** (IV/Intranasal, short-acting) and **"Naltrexone is for Maintenance"** (Oral, long-acting). 3. **Contraindication:** It should never be given to a patient currently dependent on opioids without detoxification, as it will precipitate **acute withdrawal syndrome**. 4. **Vivitrol:** This is the extended-release injectable form of Naltrexone given once monthly.

Question 325: Buprenorphine is a partial agonist of which receptor?

A. Mu receptor (Correct Answer)
B. Delta receptor
C. Kappa receptor
D. Sigma receptor

Explanation: **Explanation:** **Buprenorphine** is a unique semi-synthetic opioid derivative. It is classified as a **partial Mu (μ) receptor agonist** [2] and a **Kappa (κ) receptor antagonist**. 1. **Why Mu receptor is correct:** Buprenorphine binds with high affinity but low intrinsic activity to the Mu receptor [2], [3]. This results in a "ceiling effect" for respiratory depression and euphoria [1], making it safer in overdose compared to full agonists like morphine. However, due to its high binding affinity, it can displace full agonists, potentially precipitating withdrawal in opioid-dependent individuals [3]. 2. **Why other options are incorrect:** * **Kappa (κ) receptor:** Buprenorphine acts as an **antagonist** at this receptor. This antagonism is clinically significant as it contributes to its antidepressant effects and lack of psychotomimetic side effects (like dysphoria) typically associated with Kappa agonists. * **Delta (δ) receptor:** Buprenorphine has relatively low affinity/activity here; it is primarily considered an antagonist at Delta receptors. * **Sigma (σ) receptor:** This is no longer classified as a true opioid receptor. It is associated with hallucinations and dysphoria (seen with drugs like Pentazocine), but it is not the primary site of action for Buprenorphine. **High-Yield Clinical Pearls for NEET-PG:** * **Ceiling Effect:** Buprenorphine exhibits a ceiling effect for respiratory depression, enhancing its safety profile [1]. * **Opioid Substitution Therapy:** It is used in the management of opioid addiction (detoxification and maintenance) [1]. * **Naloxone Resistance:** Because Buprenorphine dissociates very slowly from Mu receptors, respiratory depression caused by it is difficult to reverse with standard doses of Naloxone [1]. * **Route:** It undergoes extensive first-pass metabolism, so it is administered **sublingually**, parenterally, or via transdermal patches [1].

Question 326: Serum Lithium level is increased by all the following drugs EXCEPT?

A. Aspirin
B. Chlorthiazide
C. Tetracycline
D. Verapamil (Correct Answer)

Explanation: **Explanation:** The serum concentration of Lithium is primarily regulated by renal excretion. Lithium is handled by the kidneys similarly to sodium; any drug or condition that decreases the renal clearance of Lithium or increases its proximal tubular reabsorption will lead to increased serum levels and potential toxicity. **Why Verapamil is the Correct Answer:** Verapamil is a Calcium Channel Blocker (CCB). Unlike the other options, Verapamil (and Diltiazem) typically **decreases** or has no significant effect on serum lithium levels. Interestingly, Verapamil can actually increase the neurotoxicity of lithium even when serum levels remain within the therapeutic range, but it does not cause an increase in the serum concentration itself. **Analysis of Incorrect Options:** * **Aspirin (and other NSAIDs):** NSAIDs inhibit the synthesis of prostaglandins (PGE2), which normally maintain renal blood flow. Reduced prostaglandins lead to decreased renal perfusion and decreased lithium clearance, thereby **increasing** lithium levels. (Note: Aspirin is often cited as having a lesser effect than other NSAIDs, but in the context of this classic MCQ, it is grouped with drugs that increase levels). * **Chlorthiazide (Thiazide Diuretics):** These are the most notorious for increasing lithium levels. By inhibiting sodium reabsorption in the distal tubule, they cause compensatory **increased reabsorption** of sodium and lithium in the proximal tubule. * **Tetracycline:** Certain antibiotics, including Tetracyclines and Metronidazole, can reduce the renal clearance of lithium through nephrotoxic mechanisms, leading to **increased** levels. **High-Yield Clinical Pearls for NEET-PG:** * **Drugs that INCREASE Lithium levels:** Thiazides (Highest risk), NSAIDs (except Sulindac/Aspirin in some texts, but generally all), ACE inhibitors, and ARBs. * **Drugs that DECREASE Lithium levels:** Acetazolamide, Theophylline, Caffeine, and Osmotic diuretics (Mannitol). * **Therapeutic Range:** 0.6–1.2 mEq/L. Toxicity usually manifests above 1.5 mEq/L. * **Pregnancy:** Lithium is associated with **Ebstein’s Anomaly** (tricuspid valve malformation).

Question 327: Aspirin inhibits which of the following enzymes?

A. Lipoprotein lipase
B. Lipooxygenase
C. Cyclooxygenase (Correct Answer)
D. Phospholipase d

Explanation: **Explanation:** **Mechanism of Action (Why C is correct):** Aspirin (Acetylsalicylic acid) is a Non-Steroidal Anti-Inflammatory Drug (NSAID) that acts by **irreversibly inhibiting the Cyclooxygenase (COX-1 and COX-2) enzymes**. It achieves this by covalently attaching an acetyl group to a serine residue at the active site of the enzyme. This blockade prevents the conversion of arachidonic acid into pro-inflammatory mediators, specifically **Prostaglandins, Prostacyclin, and Thromboxane A2 (TXA2)**. **Analysis of Incorrect Options:** * **A. Lipoprotein lipase:** This enzyme is responsible for the hydrolysis of triglycerides in chylomicrons and VLDLs. It is not a target for NSAIDs. * **B. Lipooxygenase (LOX):** This enzyme converts arachidonic acid into Leukotrienes. While some newer drugs (like Zileuton) target this pathway, Aspirin does not inhibit LOX. In fact, by blocking the COX pathway, Aspirin can "shunt" arachidonic acid toward the LOX pathway, potentially leading to **Aspirin-Exacerbated Respiratory Disease (AERD)** or "Aspirin Asthma." * **D. Phospholipase:** Phospholipase A2 is the enzyme that releases arachidonic acid from membrane phospholipids. This enzyme is inhibited by **Corticosteroids** (via lipocortin/annexin A1), not Aspirin. **High-Yield Clinical Pearls for NEET-PG:** * **Irreversibility:** Aspirin is the only NSAID that inhibits COX enzymes **irreversibly**. * **Antiplatelet Effect:** Because platelets cannot synthesize new proteins, the inhibition of COX-1 (and subsequent TXA2 production) lasts for the entire lifespan of the platelet (**8–11 days**). * **Zero-Order Kinetics:** At high/toxic doses, Aspirin metabolism shifts from first-order to zero-order kinetics. * **Reye’s Syndrome:** Aspirin is contraindicated in children with viral infections (like Varicella or Influenza) due to the risk of fulminant hepatic failure and encephalopathy.

Question 328: Phenylbutazone use as an NSAID is restricted because:

A. It has lower anti-inflammatory efficacy than other NSAIDs.
B. It has potential to cause agranulocytosis. (Correct Answer)
C. It has weak analgesic action.
D. It alters the protein binding and metabolism of many drugs.

Explanation: **Explanation:** **1. Why Option B is Correct:** Phenylbutazone is a pyrazolone derivative that was once widely used for its potent anti-inflammatory properties. However, its clinical use is now severely restricted (primarily to severe cases of ankylosing spondylitis or acute gout unresponsive to other treatments) due to its **idiosyncratic bone marrow toxicity**. The most serious adverse effect is **agranulocytosis** (and occasionally aplastic anemia), which can be fatal. Unlike dose-dependent side effects, this reaction is unpredictable and can occur even with short-term use, making the risk-benefit ratio unfavorable compared to newer NSAIDs. **2. Why Other Options are Incorrect:** * **Option A & C:** These are incorrect because Phenylbutazone is actually a **very potent** anti-inflammatory and analgesic agent. Its efficacy is comparable to or higher than many modern NSAIDs; the restriction is purely due to safety concerns, not lack of potency. * **Option D:** While Phenylbutazone does indeed cause significant drug interactions by displacing drugs (like warfarin or sulfonylureas) from plasma proteins and inhibiting their metabolism, this is a manageable clinical concern. It is not the primary reason for the near-total restriction of the drug; the life-threatening hematological toxicity (Option B) is the deciding factor. **3. High-Yield Clinical Pearls for NEET-PG:** * **Metabolite:** Oxyphenbutazone is the active metabolite of Phenylbutazone. * **Uricosuric Action:** Phenylbutazone has mild uricosuric properties, which is why it was historically used in gout. * **Sodium Retention:** It causes significant salt and water retention, making it contraindicated in patients with heart failure or hypertension. * **Exam Tip:** Whenever "Phenylbutazone" or "Metamizole (Analgin)" appears in NEET-PG, always look for **Agranulocytosis** as the key associated side effect.

Question 329: Mechanism of action of aspirin is inhibition of:

A. Thromboxane A2 synthesis (Correct Answer)
B. Phosphodiesterase
C. HMG-CoA reductase
D. Pancreatic lipase

Explanation: **Explanation:** **Aspirin (Acetylsalicylic Acid)** is a non-selective Non-Steroidal Anti-inflammatory Drug (NSAID) that acts by **irreversibly inhibiting** the enzymes Cyclooxygenase-1 (COX-1) and COX-2 [1], [2]. It achieves this by acetylating a specific serine residue at the active site of the enzyme [2]. In platelets, COX-1 is responsible for the production of **Thromboxane A2 (TXA2)**, a potent vasoconstrictor and platelet aggregator. Since platelets are anucleated and cannot synthesize new enzymes, the inhibition lasts for the entire lifespan of the platelet (approx. 7–10 days). This makes aspirin an effective antiplatelet agent for the prophylaxis of myocardial infarction and stroke [3]. **Analysis of Incorrect Options:** * **B. Phosphodiesterase (PDE):** Inhibited by drugs like Sildenafil (PDE-5), Milrinone (PDE-3), or Theophylline (non-selective). * **C. HMG-CoA Reductase:** This is the rate-limiting enzyme in cholesterol synthesis, inhibited by **Statins** (e.g., Atorvastatin). * **D. Pancreatic Lipase:** Inhibited by **Orlistat**, an anti-obesity drug that prevents the absorption of dietary fats. **High-Yield Clinical Pearls for NEET-PG:** * **Zero-order kinetics:** Aspirin follows first-order kinetics at low doses but shifts to zero-order kinetics at anti-inflammatory/toxic doses. * **Reye’s Syndrome:** Aspirin is contraindicated in children with viral infections (Varicella/Influenza) due to the risk of hepatic encephalopathy. * **Samter’s Triad:** Aspirin-exacerbated respiratory disease (AERD) consisting of asthma, nasal polyps, and aspirin sensitivity. * **Toxicity:** Salicylism presents with **tinnitus** (earliest sign), respiratory alkalosis, and metabolic acidosis. Management involves urinary alkalinization.

Question 330: Which of the following drugs is useful in chronic gout but is NOT a uricosuric agent?

A. Probenecid
B. Phenylbutazone
C. Sulfinpyrazone
D. Allopurinol (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. Allopurinol** **1. Why Allopurinol is Correct:** Chronic gout is managed by lowering serum uric acid levels through two primary mechanisms: decreasing production or increasing excretion. **Allopurinol** is a **Xanthine Oxidase inhibitor**. It works by inhibiting the enzyme responsible for converting hypoxanthine to xanthine and xanthine to uric acid. Therefore, it reduces the *synthesis* of uric acid rather than increasing its renal excretion. It is the first-line drug for chronic gout, especially in "over-producers" of uric acid. **2. Why Other Options are Incorrect:** * **Probenecid (A):** This is a classic **uricosuric agent**. It inhibits the URAT1 transporter in the proximal convoluted tubule, blocking the reabsorption of uric acid and increasing its excretion in urine. * **Sulfinpyrazone (C):** Like probenecid, this is a potent **uricosuric agent** that inhibits renal tubular reabsorption of uric acid. * **Phenylbutazone (B):** This is an NSAID with weak uricosuric properties. While it has anti-inflammatory effects, it is rarely used today due to toxicity (e.g., agranulocytosis), but it technically falls into the category of drugs that increase uric acid excretion. **3. NEET-PG High-Yield Pearls:** * **Drug of Choice:** Allopurinol is the DOC for chronic gout in patients with renal impairment or a history of renal stones (where uricosurics are contraindicated). * **Hypersensitivity:** Watch for **HLA-B*5801** allele; patients with this gene are at high risk for Allopurinol Hypersensitivity Syndrome (SJS/TEN). * **Acute Attack Warning:** Never start Allopurinol during an acute attack of gout, as a sudden drop in serum urate can mobilize crystals from joints and worsen the inflammation. * **Drug Interaction:** Allopurinol inhibits the metabolism of **6-Mercaptopurine** and **Azathioprine**. If co-administered, the dose of these cytotoxic drugs must be reduced by 75%.

Practice by Chapter

NSAIDs: Classification and Mechanism

Practice Questions

COX-2 Selective Inhibitors

Practice Questions

Acetaminophen (Paracetamol)

Practice Questions

Opioid Analgesics and Antagonists

Practice Questions

Drugs Used in Gout and Hyperuricemia

Practice Questions

Drugs Used in Rheumatoid Arthritis

Practice Questions

Disease-Modifying Antirheumatic Drugs

Practice Questions

Glucocorticoids as Anti-inflammatory Agents

Practice Questions

Migraine Therapeutics

Practice Questions

Neuropathic Pain Management

Practice Questions

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