Analgesics and Anti-inflammatory Drugs — MCQs

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

Question 181: A patient presents with severe shortness of breath whenever they take aspirin for a headache. Which of the following is most likely responsible for this effect?

A. Leukotrienes (Correct Answer)
B. Prostaglandin E
C. Thromboxane A2
D. Prostacyclin

Explanation: This clinical scenario describes **Aspirin-Exacerbated Respiratory Disease (AERD)**, historically known as Samter’s Triad (asthma, nasal polyps, and aspirin sensitivity). **Why Leukotrienes are the correct answer:** Aspirin works by irreversibly inhibiting the enzyme **Cyclooxygenase (COX)**. [1] Under normal conditions, Arachidonic acid is metabolized via two main pathways: the COX pathway (producing prostaglandins and thromboxanes) and the **5-Lipoxygenase (5-LOX) pathway** (producing leukotrienes). When aspirin blocks the COX pathway, arachidonic acid metabolism is "shunted" toward the 5-LOX pathway. This leads to an overproduction of **Cysteinyl Leukotrienes (LTC4, LTD4, and LTE4)**. These are potent bronchoconstrictors that cause airway edema, mucus secretion, and the severe shortness of breath (bronchospasm) seen in sensitive patients. [2] **Why the other options are incorrect:** * **B. Prostaglandin E (PGE2):** PGE2 actually has bronchodilatory and protective effects on the airways. Aspirin *decreases* PGE2 levels; it is the loss of PGE2’s inhibitory effect on leukotriene synthesis that further worsens the condition. * **C. Thromboxane A2 (TXA2):** Produced by COX-1 in platelets, TXA2 causes platelet aggregation and vasoconstriction. While aspirin inhibits TXA2, this does not cause respiratory distress. * **D. Prostacyclin (PGI2):** Produced by vascular endothelium, PGI2 causes vasodilation and inhibits platelet aggregation. Its inhibition by aspirin is related to gastric and cardiovascular effects, not bronchospasm. **High-Yield NEET-PG Pearls:** * **Management:** The drug of choice for managing AERD is **Leukotriene Receptor Antagonists (LTRAs)** like **Montelukast** or **Zafirlukast**. [3] * **Aspirin Desensitization:** This is the definitive treatment for patients who require aspirin for cardiovascular protection despite sensitivity. * **Cross-reactivity:** Patients with aspirin sensitivity often react to other non-selective NSAIDs (e.g., Ibuprofen, Naproxen) because they also inhibit COX-1. Acetaminophen is usually a safer alternative in low doses.

Question 182: Which of the following opioid analgesics is most likely to cause central nervous system (CNS) disturbance?

A. heroin
B. morphine
C. meperidine (Correct Answer)
D. fentanyl

Explanation: The correct answer is **Meperidine** (also known as Pethidine). The primary reason for its association with CNS disturbances lies in its metabolism [3], [4]. 1. **Why Meperidine is correct:** Meperidine is metabolized in the liver by N-demethylation to **normeperidine**, an active metabolite [3]. Unlike meperidine, which is a sedative, normeperidine is a potent **CNS stimulant**. It has a longer half-life (15–20 hours) and accumulates, especially in patients with renal impairment [4]. Accumulation leads to CNS hyperexcitability, manifesting as tremors, muscle twitches, hyperreflexia, and **seizures** [4]. 2. **Why other options are incorrect:** * **Morphine:** While it can cause sedation and respiratory depression, its primary metabolites (Morphine-6-glucuronide) are mainly associated with analgesia and respiratory effects, not CNS excitation/seizures. * **Heroin (Diacetylmorphine):** A highly lipid-soluble prodrug that rapidly converts to morphine in the brain [1]. Its side effect profile mirrors morphine but with higher addiction potential. * **Fentanyl:** A potent synthetic opioid used in anesthesia. It is known for cardiovascular stability and lacks the excitatory metabolites seen with meperidine. **NEET-PG High-Yield Pearls:** * **Serotonin Syndrome:** Meperidine inhibits the reuptake of serotonin. It is strictly contraindicated with **MAO Inhibitors**, as the combination can trigger a fatal hyperpyrexic coma or serotonin syndrome [2]. * **Mydriasis:** Unlike most opioids that cause "pinpoint pupils" (miosis), meperidine can cause **mydriasis** due to its atropine-like (antimuscarinic) structural properties [4]. * **Clinical Use:** It is specifically indicated for **shivering** (post-operative or drug-induced) but is no longer preferred for chronic pain due to metabolite toxicity [4].

Question 183: Glucocorticoids act in inflammation by inhibiting which of the following?

A. Lipocortin
B. Interleukin-2
C. Lipocortin (Correct Answer)
D. C-reactive protein

Explanation: **Explanation:** Glucocorticoids exert their potent anti-inflammatory effects primarily by modulating gene expression. The correct mechanism involves the **induction (stimulation)** of a protein called **Lipocortin-1** (also known as Annexin A1). 1. **Why Lipocortin is the key:** Glucocorticoids bind to intracellular receptors, which then move to the nucleus to increase the synthesis of Lipocortin. Lipocortin acts as a potent inhibitor of the enzyme **Phospholipase A2 (PLA2)**. Since PLA2 is responsible for releasing Arachidonic acid from membrane phospholipids, its inhibition prevents the formation of both Prostaglandins (via the COX pathway) and Leukotrienes (via the LOX pathway). *Note: There appears to be a slight technical error in the question's phrasing—Glucocorticoids **induce** Lipocortin to **inhibit** PLA2. However, in the context of standard medical exams, Lipocortin is the primary mediator associated with their anti-inflammatory action.* **Analysis of Incorrect Options:** * **Interleukin-2 (IL-2):** While steroids do decrease the production of IL-2 (leading to immunosuppression), this is a downstream effect of NF-κB inhibition, not the primary mechanism involving Lipocortin. * **C-reactive protein (CRP):** CRP is an acute-phase reactant produced by the liver. While steroid therapy eventually lowers CRP levels by reducing overall inflammation, it is a marker of inflammation rather than the direct molecular target. **NEET-PG High-Yield Pearls:** * **Dual Inhibition:** Unlike NSAIDs (which only inhibit COX), steroids inhibit both COX and LOX pathways by acting upstream on PLA2. * **Genomic vs. Non-genomic:** Most effects are genomic (slow onset), but they also inhibit **NF-κB**, a major pro-inflammatory transcription factor. * **Metabolic Side Effects:** Remember the mnemonic **"S"** for Steroids: **S**ugar increases (Hyperglycemia), **S**alt increases (Hypernatremia/Edema), **S**ex hormones decrease, and **S**tomach acid increases (Peptic ulcers).

Question 184: Which of the following statements about drugs used in rheumatoid arthritis is false?

A. Tofacitinib inhibits JAK1 and JAK3
B. Tocilizumab inhibits IL-6
C. Tofacitinib is given intravenously (Correct Answer)
D. Tocilizumab is given by intravenous and subcutaneous routes

Explanation: ### Explanation The correct answer is **C (Tofacitinib is given intravenously)** because it is a false statement. **1. Why Option C is the correct answer (False statement):** Tofacitinib is a **Janus Kinase (JAK) inhibitor**, categorized as a "Targeted Synthetic DMARD" (tsDMARD). Unlike biological DMARDs (which are proteins/monoclonal antibodies and must be injected), Tofacitinib is a small molecule drug. Its primary clinical advantage is that it is **administered orally** (usually 5 mg twice daily), not intravenously. **2. Analysis of other options:** * **Option A (True):** Tofacitinib is a non-selective JAK inhibitor that primarily inhibits **JAK1 and JAK3**, and to a lesser extent JAK2. This blocks the signaling pathway for various cytokines involved in lymphocyte activation. * **Option B (True):** **Tocilizumab** is a recombinant humanized monoclonal antibody that acts as an **IL-6 receptor antagonist**. IL-6 is a key pro-inflammatory cytokine in the pathogenesis of Rheumatoid Arthritis (RA). * **Option D (True):** Tocilizumab is versatile in its administration; it can be given as an **intravenous (IV) infusion** (usually monthly) or as a **subcutaneous (SC) injection** (usually weekly). **3. High-Yield Clinical Pearls for NEET-PG:** * **JAK Inhibitors:** Other examples include Baricitinib (JAK1/2) and Upadacitinib (JAK1 selective). All are **oral**. * **Pre-treatment Screening:** Before starting Tofacitinib or Biologics, always screen for **Latent TB** (using Mantoux or IGRA) and Hepatitis B/C, as these drugs can cause reactivation. * **Adverse Effects of Tofacitinib:** Increased risk of serious infections, herpes zoster reactivation, and changes in lipid profiles (increased LDL/HDL). * **IL-1 Inhibitor:** Anakinra (not to be confused with IL-6 inhibitors).

Question 185: All the following drugs are reversible inhibitors of COX EXCEPT?

A. Diclofenac
B. Ibuprofen
C. Aspirin (Correct Answer)
D. Indomethacin

Explanation: ### Explanation **Correct Answer: C. Aspirin** **Mechanism of Action:** The core concept here is the nature of the chemical bond formed between the drug and the enzyme Cyclooxygenase (COX). Most Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) bind to the active site of COX via non-covalent interactions, making them **reversible inhibitors**. **Aspirin (Acetylsalicylic acid)** is unique because it **irreversibly** inhibits COX-1 and COX-2. It achieves this by covalently attaching an acetyl group to a specific serine residue (Serine 529 in COX-1 and Serine 516 in COX-2) near the active site. This permanent modification physically blocks the channel, preventing arachidonic acid from reaching the catalytic site. The enzyme remains inactive for its entire lifespan; recovery of function requires the synthesis of new enzyme molecules. **Analysis of Incorrect Options:** * **A. Diclofenac:** A potent phenylacetic acid derivative that acts as a competitive, reversible inhibitor of COX. * **B. Ibuprofen:** A propionic acid derivative that reversibly competes with arachidonic acid for the COX binding site. * **D. Indomethacin:** An indole derivative and a powerful reversible inhibitor of COX, often used for closing a Patent Ductus Arteriosus (PDA). **High-Yield Clinical Pearls for NEET-PG:** * **Antiplatelet Effect:** Because platelets lack a nucleus, they cannot synthesize new COX enzymes. A single low dose of Aspirin inhibits platelet COX-1 for the remainder of the platelet's life (7–10 days), explaining its use in cardiovascular prophylaxis. * **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 (e.g., influenza, varicella) due to the risk of fulminant hepatic failure and encephalopathy. * **Aspirin Triad (Samter’s Triad):** Asthma, Nasal polyposis, and Aspirin hypersensitivity.

Question 186: Leflunomide, used in the treatment of Rheumatoid arthritis, acts by inhibiting which enzyme?

A. Inosine monophosphate dehydrogenase
B. Dihydroorotate dehydrogenase (Correct Answer)
C. Aldehyde dehydrogenase
D. TNF-α receptor

Explanation: **Explanation:** **Leflunomide** is a Disease-Modifying Antirheumatic Drug (DMARD) used primarily in the management of Rheumatoid Arthritis (RA). **Mechanism of Action:** Leflunomide is a prodrug that is converted in the body to its active metabolite, **A77 1726**. This metabolite inhibits the mitochondrial enzyme **Dihydroorotate Dehydrogenase (DHODH)**. This enzyme is critical for the **de novo synthesis of pyrimidines** (specifically UMP). Since activated T-lymphocytes depend on de novo synthesis to expand and proliferate (unlike other cells which can use the salvage pathway), Leflunomide effectively arrests these cells in the G1 phase, reducing the autoimmune inflammatory response. **Analysis of Incorrect Options:** * **A. Inosine monophosphate dehydrogenase (IMPDH):** This is the target of **Mycophenolate Mofetil**. It inhibits the de novo synthesis of **purines** rather than pyrimidines. * **C. Aldehyde dehydrogenase:** This enzyme is inhibited by **Disulfiram**, used in the treatment of chronic alcoholism to induce a sensitive reaction to alcohol. * **D. TNF-α receptor:** Drugs like **Etanercept** act as decoy receptors for TNF-α, while Adalimumab and Infliximab are monoclonal antibodies against TNF-α. Leflunomide does not directly bind to these receptors. **High-Yield Clinical Pearls for NEET-PG:** * **Loading Dose:** Leflunomide has a very long half-life (approx. 2 weeks); hence, a loading dose is often used. * **Side Effects:** Hepatotoxicity (monitor LFTs) and diarrhea are common. It is highly **teratogenic**. * **Washout Procedure:** If a patient needs to stop the drug (e.g., for pregnancy), **Cholestyramine** is administered to enhance biliary excretion and "wash out" the drug quickly.

Question 187: Pethidine differs from morphine in producing which of the following effect?

A. Sedation
B. Tachycardia (Correct Answer)
C. Euphoria
D. All of the above

Explanation: ### Explanation The correct answer is **Tachycardia**. **1. Why Tachycardia is the correct answer:** Morphine and most other opioids typically cause **bradycardia** due to central vagal stimulation. However, **Pethidine (Meperidine)** is unique because its chemical structure is related to **Atropine**. Due to this inherent antimuscarinic (atropine-like) activity, pethidine causes **tachycardia** instead of bradycardia. This is a classic "exception" frequently tested in pharmacology. **2. Why other options are incorrect:** * **Sedation (A):** Both morphine and pethidine are CNS depressants that produce significant sedation. While pethidine is sometimes perceived as "less sedating" in clinical practice, it is not a point of pharmacological difference in terms of the effect produced. * **Euphoria (C):** Both drugs act on $\mu$-opioid receptors in the brain to produce euphoria, which contributes to their high abuse potential. * **All of the above (D):** Since sedation and euphoria are common to both drugs, this option is incorrect. **3. High-Yield Clinical Pearls for NEET-PG:** * **Mydriasis:** Unlike morphine (which causes "pinpoint pupils" via Edinger-Westphal nucleus stimulation), pethidine can cause **mydriasis** (pupillary dilation) due to its atropine-like action. * **Seizures:** Pethidine is metabolized to **norpethidine**, which is a CNS stimulant. In patients with renal failure or chronic use, norpethidine accumulation can lead to tremors and **seizures**. * **Smooth Muscle:** Pethidine has less inhibitory effect on the Sphincter of Oddi compared to morphine, making it traditionally preferred (though still controversial) in biliary colic. * **Interaction:** Pethidine is contraindicated with **MAO inhibitors** as it can precipitate a life-threatening "Serotonin Syndrome" (hyperpyrexia, coma, and convulsions).

Question 188: Anti-histone antibodies are characteristic of which condition?

A. Drug-induced lupus erythematosus (Correct Answer)
B. Cardiac lupus erythematosus
C. Lupus nephritis
D. Mixed connective tissue disease

Explanation: **Explanation:** **Anti-histone antibodies** are the hallmark serological marker for **Drug-induced Lupus Erythematosus (DILE)**. While Anti-nuclear antibodies (ANA) are positive in both systemic and drug-induced lupus, anti-histone antibodies are found in >95% of DILE cases but only about 50% of Systemic Lupus Erythematosus (SLE) cases. **Analysis of Options:** * **A. Drug-induced Lupus Erythematosus (Correct):** DILE is a lupus-like syndrome caused by the chronic use of certain drugs. It typically presents with fever, malaise, arthralgia, and serositis, but notably lacks the renal and CNS involvement seen in idiopathic SLE. * **B & C. Cardiac Lupus and Lupus Nephritis:** These are systemic manifestations of idiopathic SLE. In these conditions, **Anti-dsDNA** antibodies are highly specific and correlate with disease activity (especially renal involvement), whereas anti-histone antibodies are non-specific. * **D. Mixed Connective Tissue Disease (MCTD):** The characteristic serological marker for MCTD is **Anti-U1 RNP** antibody. **High-Yield Clinical Pearls for NEET-PG:** * **Common offending drugs (Mnemonic: SHIPP):** **S**ulfonamides, **H**ydralazine (highest risk), **I**soniazid, **P**rocainamide (highest frequency), and **P**henytoin. Other notable drugs include Minocycline and Anti-TNF alpha agents. * **Metabolism Link:** DILE is more common in **slow acetylators** (due to the genetically determined N-acetyltransferase enzyme deficiency). * **Key Difference:** Unlike SLE, DILE symptoms usually resolve upon discontinuation of the offending drug. * **Serology:** ANA is positive (sensitive), Anti-histone is positive (specific for DILE context), but **Anti-dsDNA and Hypocomplementemia (low C3/C4) are typically absent.**

Question 189: Which among the following is a pure antagonist of opioid receptors?

A. Naltrexone (Correct Answer)
B. Nalbuphine
C. Butorphanol
D. Pentazocine

Explanation: ### Explanation **1. Why Naltrexone is the Correct Answer:** Naltrexone is a **competitive, pure opioid antagonist** at $\mu$ (mu), $\kappa$ (kappa), and $\delta$ (delta) receptors, with the highest affinity for $\mu$ receptors. Unlike mixed agonists-antagonists, it possesses no intrinsic activity; it works solely by displacing opioids from their receptors and blocking their effects. * **Pharmacokinetics:** It is orally effective with a long duration of action (up to 24–48 hours), making it ideal for maintenance therapy in opioid de-addiction and alcohol dependence. **2. Why the Other Options are Incorrect:** * **Nalbuphine (Option B):** It is a **mixed agonist-antagonist**. It acts as a $\kappa$-receptor agonist but a $\mu$-receptor antagonist. It is often used for moderate-to-severe pain and has a "ceiling effect" on respiratory depression. * **Butorphanol (Option C):** Similar to nalbuphine, it is a **mixed agonist-antagonist** ($\kappa$ agonist, $\mu$ partial agonist/antagonist). It is frequently used for post-operative pain and migraine (nasal spray). * **Pentazocine (Option D):** This is a **mixed agonist-antagonist** ($\kappa$ agonist, $\mu$ weak antagonist/partial agonist). It was the first such drug developed but is known for causing dysphoria and psychotomimetic effects due to $\sigma$ (sigma) receptor activation. **3. NEET-PG High-Yield Pearls:** * **Naloxone vs. Naltrexone:** Naloxone is the drug of choice for **acute opioid poisoning** (given IV due to high first-pass metabolism; short-acting). Naltrexone is used for **long-term maintenance** (given orally; long-acting). * **Methylnaltrexone/Alvimopan:** These are peripheral opioid antagonists used to treat opioid-induced constipation without reversing analgesia. * **Nalmefene:** Another pure antagonist with a longer half-life than naloxone, used in alcohol dependence. * **Warning:** Administering any antagonist (pure or mixed) to an opioid-dependent patient will precipitate **acute withdrawal syndrome**.

Question 190: Which NSAID undergoes enterohepatic circulation?

A. Phenylbutazone
B. Piroxicam (Correct Answer)
C. Aspirin
D. Ibuprofen

Explanation: ### Explanation **Correct Option: B. Piroxicam** **Mechanism and Concept:** Piroxicam is a long-acting non-selective COX inhibitor belonging to the **Oxicam** class. The primary reason for its exceptionally long half-life (approximately 50 hours) is its extensive **enterohepatic circulation**. After being metabolized in the liver and excreted into the bile, a significant portion of the drug is reabsorbed from the gastrointestinal tract back into the systemic circulation. This recycling mechanism allows for convenient **once-daily dosing**, which is a hallmark of Piroxicam. **Analysis of Incorrect Options:** * **A. Phenylbutazone:** This is a pyrazolone derivative. While it has a long half-life (up to 70 hours), it is primarily due to slow metabolic transformation and high plasma protein binding, not significant enterohepatic recycling. It is rarely used now due to the risk of agranulocytosis. * **C. Aspirin:** Aspirin is a salicylate that undergoes rapid hydrolysis to salicylic acid. It follows first-order kinetics at low doses and zero-order kinetics at high doses, but it does not undergo significant enterohepatic circulation. * **D. Ibuprofen:** A propionic acid derivative with a very short half-life (approx. 2 hours). It is rapidly metabolized and excreted in the urine, requiring frequent dosing (3–4 times daily). **High-Yield Facts for NEET-PG:** * **Longest acting NSAID:** Piroxicam (due to enterohepatic circulation). * **Shortest acting NSAID:** Diclofenac or Ibuprofen. * **Clinical Pearl:** Because of its long half-life, Piroxicam takes about 7–10 days to reach steady-state plasma concentrations. It is also associated with a higher risk of **GI mucosal toxicity** and Peptic Ulcer Disease compared to other NSAIDs. * **Other drugs with Enterohepatic Circulation:** Morphine, Estrogen, Chloramphenicol, and Indomethacin (another NSAID that undergoes this process, though less prominently than Piroxicam).

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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