Analgesics and Anti-inflammatory Drugs — MCQs

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

Question 51: Which among the following drugs is contraindicated in renal failure?

A. Pethidine (Correct Answer)
B. Morphine
C. Fentanyl
D. Atracurium

Explanation: ### Explanation **Correct Option: A. Pethidine** Pethidine (Meperidine) is strictly contraindicated in renal failure due to its metabolism. It is metabolized in the liver to **Norpethidine**, an active metabolite. Norpethidine has a long half-life and is primarily excreted by the kidneys. In renal impairment, norpethidine accumulates, leading to **CNS toxicity**. This manifests as irritability, tremors, hallucinations, and most characteristically, **seizures**. Unlike pethidine, norpethidine-induced seizures are not reversed by Naloxone; in fact, Naloxone may worsen them by lowering the seizure threshold. **Analysis of Incorrect Options:** * **B. Morphine:** While Morphine should be used with extreme caution in renal failure (due to the accumulation of *Morphine-6-glucuronide*, which causes prolonged respiratory depression), it is generally considered a "relative contraindication" compared to the absolute risk of seizures with Pethidine. * **C. Fentanyl:** This is the **opioid of choice** in renal failure. It has no active metabolites and is primarily cleared by hepatic metabolism, making it safe for patients with impaired kidney function. * **D. Atracurium:** This is a neuromuscular blocker, not an analgesic. It is the **muscle relaxant of choice** in renal failure because it undergoes **Hofmann elimination** (spontaneous non-enzymatic degradation), which is independent of renal or hepatic function. **High-Yield Clinical Pearls for NEET-PG:** * **Pethidine & MAO Inhibitors:** Co-administration can lead to a life-threatening **Serotonin Syndrome** (hyperpyrexia, excitation). * **Pethidine in Obstetrics:** It is often preferred during labor as it causes less inhibition of uterine contractions compared to morphine. * **Drug of Choice for Biliary Colic:** Pethidine is traditionally preferred over morphine because it causes less spasm of the **Sphincter of Oddi**.

Question 52: Acute gouty arthritis is seen early following treatment with which of the following medications?

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

Explanation: **Explanation:** **Why Allopurinol is the Correct Answer:** Allopurinol is a **Xanthine Oxidase Inhibitor** used for the long-term management of chronic gout. When initiated, it causes a rapid decline in serum uric acid levels. This sudden drop triggers the **mobilization and dissolution of urate crystals** (monosodium urate) from tissue stores (tophi) into the joint space. These "naked" crystals are highly pro-inflammatory, leading to the precipitation of an **acute gouty flare**. This phenomenon is known as "mobilization gout." To prevent this, Allopurinol should always be co-administered with low-dose Colchicine or NSAIDs for the first 3–6 months. **Analysis of Incorrect Options:** * **Rasburicase (A):** This is a recombinant urate oxidase enzyme that converts uric acid into allantoin (a highly soluble metabolite). It is primarily used for **Tumor Lysis Syndrome**. While it lowers uric acid rapidly, it is not typically associated with the clinical "flare" seen during chronic gout management. * **Probenecid (B) & Sulfinpyrazone (D):** These are **Uricosuric agents** that inhibit the reabsorption of uric acid in the proximal tubule. While they can theoretically cause flares, Allopurinol is the classic and most common culprit tested in exams regarding treatment-induced acute gouty arthritis. **High-Yield Clinical Pearls for NEET-PG:** * **Rule of Thumb:** Never start Allopurinol during an acute attack of gout; wait 2–4 weeks after the attack has subsided. * **Drug of Choice (DOC):** * Acute Gout: **NSAIDs** (e.g., Indomethacin, Naproxen). * Acute Gout in Renal Failure: **Corticosteroids**. * Chronic Gout (Overproducers/Underexcretors): **Allopurinol**. * **HLA-B*5801:** Testing is recommended in certain populations before starting Allopurinol to prevent **Stevens-Johnson Syndrome (SJS)**.

Question 53: Which drug is useful for the management of gout?

A. Pyrazinamide
B. Rifampicin
C. Allopurinol (Correct Answer)
D. Naloxone

Explanation: Gout is a metabolic disorder characterized by hyperuricemia leading to the deposition of monosodium urate crystals in joints. **Allopurinol** is the drug of choice for the chronic management of gout (intercritical period) [2]. It is a **hypouricemic agent** that acts as a structural analog of hypoxanthine [2]. It works by inhibiting the enzyme **Xanthine Oxidase**, which is responsible for converting hypoxanthine to xanthine and xanthine to uric acid [1, 2]. By blocking this pathway, it reduces the plasma concentration of uric acid [1, 2].**Analysis of Incorrect Options:** * **A. Pyrazinamide:** This is a first-line antitubercular drug. A significant side effect of Pyrazinamide is that it inhibits the renal excretion of uric acid, leading to **hyperuricemia**. Therefore, it can actually precipitate or worsen an attack of gout. * **B. Rifampicin:** Another first-line antitubercular drug. Its primary side effect is hepatotoxicity and the harmless orange-red discoloration of body fluids (urine, sweat, tears). It has no role in gout management. * **D. Naloxone:** This is a competitive **opioid antagonist** used primarily to reverse respiratory depression in opioid overdose. It has no anti-inflammatory or uricosuric properties.**High-Yield Clinical Pearls for NEET-PG:** 1. **Acute Gout Management:** NSAIDs (first-line), Colchicine, or Glucocorticoids are used for acute attacks [2, 3]. **Never start Allopurinol during an acute attack**, as a sudden change in urate levels can worsen the inflammation [2]. 2. **Febuxostat:** A newer, non-purine selective inhibitor of xanthine oxidase used if Allopurinol is not tolerated [1]. 3. **Drug Interaction:** Allopurinol inhibits the metabolism of **6-Mercaptopurine and Azathioprine**. If co-administered, the dose of these cytotoxic drugs must be reduced to 1/4th to avoid toxicity.

Question 54: All of the following are true about Aspirin except?

A. At low doses it acts as an antiplatelet drug.
B. It irreversibly inhibits the synthesis of Thromboxane.
C. It is used to inhibit Niacin induced flushing.
D. It is a reversible inhibitor of COX. (Correct Answer)

Explanation: **Explanation** The correct answer is **D**, as Aspirin is an **irreversible** inhibitor of the Cyclooxygenase (COX) enzyme, not a reversible one. **1. Why Option D is the Correct Answer (The Concept):** Aspirin (Acetylsalicylic acid) is unique among NSAIDs because it covalently modifies the COX-1 and COX-2 enzymes by **acetylating a specific serine residue** at the active site. This covalent bond permanently inactivates the enzyme. Since platelets lack a nucleus, they cannot synthesize new proteins; thus, the inhibition lasts for the entire lifespan of the platelet (approx. 8–11 days). **2. Analysis of Other Options:** * **Option A:** At low doses (75–150 mg), Aspirin selectively inhibits COX-1 in platelets, reducing Thromboxane A2 (TXA2) production, which makes it an effective **antiplatelet** agent for cardiovascular prophylaxis. * **Option B:** Because the inhibition is irreversible and platelets cannot regenerate the enzyme, the synthesis of **Thromboxane A2** is halted for the life of the cell. * **Option C:** Niacin (Vitamin B3) causes flushing mediated by **Prostaglandin D2 (PGD2)**. Pre-treatment with Aspirin inhibits COX and prevents the synthesis of these prostaglandins, thereby reducing the flushing side effect. **Clinical Pearls for NEET-PG:** * **Zero-order kinetics:** At high/toxic doses, Aspirin follows zero-order elimination. * **Reye’s Syndrome:** Avoid Aspirin in children with viral infections (Varicella/Influenza) due to the risk of hepatic encephalopathy. * **Aspirin Triad (Samter’s Triad):** Asthma, Nasal polyposis, and Aspirin hypersensitivity. * **Uric Acid:** Low-dose aspirin decreases uric acid excretion (hyperuricemia), while high-dose aspirin is uricosuric.

Question 55: Prostaglandin inhibiting action of aspirin is useful in the treatment of all of the following conditions, except:

A. Analgesia and antipyresis
B. Closure of ductus arteriosus
C. Uricosuria (Correct Answer)
D. Anti-inflammatory and antiplatelet aggregation

Explanation: **Explanation:** The therapeutic effects of Aspirin are primarily mediated by the irreversible inhibition of **Cyclooxygenase (COX-1 and COX-2)** enzymes, which prevents the synthesis of prostaglandins (PGs) and thromboxanes. **Why Uricosuria is the Correct Answer:** Aspirin’s effect on uric acid excretion is **dose-dependent** and is **not** mediated by prostaglandin inhibition. At low to moderate doses (less than 4g/day), aspirin actually inhibits the tubular secretion of uric acid, leading to hyperuricemia (which can precipitate gout). While very high doses (>5g/day) can be uricosuric by inhibiting tubular reabsorption, this is a direct effect on renal transporters (URAT1), not a result of PG inhibition. Therefore, PG inhibition is not the mechanism for uricosuria. **Analysis of Incorrect Options:** * **Analgesia and Antipyresis:** Aspirin reduces PGE2 levels in the hypothalamus (resetting the thermostat) and at peripheral nerve endings, providing relief from fever and pain. * **Closure of Ductus Arteriosus:** Patent Ductus Arteriosus (PDA) is maintained by PGE2. Inhibiting PG synthesis promotes its closure (though Indomethacin or Ibuprofen are clinically preferred). * **Anti-inflammatory and Antiplatelet:** Anti-inflammatory action occurs via COX-2 inhibition in tissues. Antiplatelet action occurs via irreversible COX-1 inhibition in platelets, preventing the formation of **Thromboxane A2 (TXA2)**. **High-Yield Clinical Pearls for NEET-PG:** 1. **Zero-Order Kinetics:** Aspirin follows zero-order kinetics at high/toxic doses. 2. **Reye’s Syndrome:** Aspirin is contraindicated in children with viral infections (use Paracetamol instead). 3. **Samter’s Triad:** Aspirin-exacerbated respiratory disease (AERD) consists of asthma, nasal polyps, and aspirin sensitivity. 4. **Low-dose Aspirin (75-150mg):** Specifically used for antiplatelet effects due to the irreversible nature of its binding.

Question 56: Icatibant is a?

A. bradykinin B1 antagonist
B. bradykinin B2 antagonist (Correct Answer)
C. bradykinin B3 antagonist
D. histamine receptor H3 antagonist

Explanation: ### Explanation **Correct Option: B. Bradykinin B2 antagonist** **Mechanism of Action:** Icatibant is a synthetic decapeptide that acts as a potent and selective **competitive antagonist at the Bradykinin B2 receptor**. Bradykinin is a key mediator in inflammatory processes and vascular permeability. In conditions like **Hereditary Angioedema (HAE)**, there is an overproduction of bradykinin due to C1-esterase inhibitor deficiency. Excessive bradykinin binds to B2 receptors on vascular endothelial cells, leading to massive vasodilation and increased capillary permeability, which results in life-threatening swelling (edema). By blocking the B2 receptor, Icatibant prevents these effects and provides symptomatic relief during acute attacks. **Analysis of Incorrect Options:** * **Option A (B1 antagonist):** B1 receptors are typically "inducible" and upregulated during chronic inflammation or tissue injury. While they play a role in pain, Icatibant does not target them. * **Option C (B3 antagonist):** There is no clinically significant "Bradykinin B3" receptor targeted by current pharmacological agents in this context. * **Option D (H3 antagonist):** Histamine H3 receptors are primarily located in the CNS and regulate neurotransmitter release. Examples include Pitolisant (used for narcolepsy), not Icatibant. **High-Yield Clinical Pearls for NEET-PG:** * **Indication:** Approved for the treatment of **acute attacks of Hereditary Angioedema (HAE)** in adults. * **Route:** Administered via **subcutaneous injection** (usually in the abdomen). * **Key Distinction:** Unlike allergic angioedema, HAE is **bradykinin-mediated**, meaning it does *not* respond to antihistamines or corticosteroids. * **Other HAE Drugs:** * **Ecallantide:** A Kallikrein inhibitor. * **Danazol:** An androgen used for prophylaxis (increases C1-esterase inhibitor levels). * **Lanadelumab:** A monoclonal antibody against plasma kallikrein.

Question 57: Which of the following anti-inflammatory drugs is a COX-2 inhibitor?

A. Aspirin
B. Ketoprofen
C. Rofecoxib (Correct Answer)
D. Sulindac

Explanation: ### Explanation **Correct Answer: C. Rofecoxib** **Mechanism and Concept:** Non-steroidal anti-inflammatory drugs (NSAIDs) act by inhibiting the enzyme **Cyclooxygenase (COX)**. There are two main isoforms: **COX-1** (constitutive, involved in gastric protection and platelet aggregation) and **COX-2** (inducible, primarily expressed during inflammation). **Rofecoxib** belongs to the "Coxib" class, which selectively inhibits COX-2. By sparing COX-1, these drugs aim to reduce the gastrointestinal side effects (like peptic ulcers) associated with traditional NSAIDs. **Analysis of Incorrect Options:** * **A. Aspirin:** An irreversible, non-selective inhibitor of both COX-1 and COX-2. At low doses, it is highly selective for COX-1 in platelets. * **B. Ketoprofen:** A traditional propionic acid derivative (like ibuprofen) that non-selectively inhibits both COX-1 and COX-2. * **D. Sulindac:** An acetic acid derivative and a prodrug. It is a non-selective COX inhibitor known for being relatively "renal-sparing" as its active sulfide metabolite is not excreted by the kidney. **High-Yield Clinical Pearls for NEET-PG:** * **Cardiovascular Risk:** While COX-2 inhibitors are gut-friendly, they increase the risk of thrombotic events (MI/Stroke) because they inhibit PGI2 (vasodilator/anti-aggregatory) without affecting Thromboxane A2 (vasoconstrictor/pro-aggregatory). This led to the withdrawal of Rofecoxib and Valdecoxib from the market. * **Celecoxib** is the only COX-2 inhibitor currently available in many markets and contains a **sulfonamide** moiety (contraindicated in sulfa allergy). * **Etoricoxib** is the most COX-2 selective agent currently used. * **Parecoxib** is the only injectable COX-2 inhibitor (prodrug of valdecoxib).

Question 58: What is the drug of choice for Rheumatoid Arthritis that is resistant to NSAIDs?

A. Methotrexate (Correct Answer)
B. Sulfasalazine
C. Corticosteroids
D. Salicylic acid

Explanation: **Explanation:** The management of Rheumatoid Arthritis (RA) follows a step-wise approach. When NSAIDs fail to control the disease progression, **Disease-Modifying Anti-Rheumatic Drugs (DMARDs)** are initiated. **1. Why Methotrexate (Option A) is correct:** Methotrexate is the **"Gold Standard"** and the **first-line DMARD** for RA. It acts by inhibiting the enzyme dihydrofolate reductase (at high doses) and increasing adenosine levels (at low doses used in RA), which exerts a potent anti-inflammatory effect. It is preferred because of its high efficacy, low cost, and relatively predictable side-effect profile compared to other DMARDs. **2. Why other options are incorrect:** * **Sulfasalazine (Option B):** While it is a DMARD used in mild cases or as part of triple therapy, it is generally considered less effective than Methotrexate and is not the primary drug of choice for resistant cases. * **Corticosteroids (Option C):** These are used as "bridge therapy" to provide rapid symptomatic relief while waiting for DMARDs to take effect. They do not halt disease progression long-term and carry significant toxicity. * **Salicylic acid (Option D):** This is an NSAID (Aspirin). If the patient is already "resistant to NSAIDs," adding another salicylate will not modify the disease course and will increase the risk of GI toxicity. **Clinical Pearls for NEET-PG:** * **Supplementation:** Always co-prescribe **Folic acid** (5 mg/week) with Methotrexate to reduce GI side effects and mucosal ulcers. * **Monitoring:** Periodic Liver Function Tests (LFTs) and CBC are mandatory due to risks of hepatotoxicity and myelosuppression. * **Contraindication:** Methotrexate is strictly **contraindicated in pregnancy** (Category X) due to its potent teratogenic effects. * **Mechanism in RA:** Unlike its anticancer role, its primary action in RA is mediated via **adenosine accumulation**.

Question 59: Infliximab is:

A. An IgG1 chimeric monoclonal antibody against TNF α (Correct Answer)
B. An IgG1 fully human monoclonal antibody against TNF α
C. A P75 TNF receptor fusion protein
D. None of the above

Explanation: **Explanation:** **Infliximab** is a potent biological agent used in the management of autoimmune conditions like Rheumatoid Arthritis, Crohn’s disease, and Psoriasis. 1. **Why Option A is Correct:** Infliximab is a **chimeric** monoclonal antibody. In pharmacology, "chimeric" means it is composed of a combination of mouse (murine) variable regions (~25%) and human constant regions (~75%). It belongs to the **IgG1** subclass and works by binding with high affinity to both soluble and transmembrane forms of **TNF-α**, neutralizing its pro-inflammatory effects. 2. **Why Other Options are Incorrect:** * **Option B:** **Adalimumab** and **Golimumab** are examples of **fully human** monoclonal antibodies against TNF-α. They are preferred in some cases because they have lower immunogenicity compared to chimeric antibodies. * **Option C:** **Etanercept** is the **P75 TNF receptor fusion protein**. It acts as a "decoy receptor" that binds to TNF molecules in the circulation, preventing them from interacting with cell surface receptors. **High-Yield Clinical Pearls for NEET-PG:** * **Nomenclature Hack:** The suffix **"-ximab"** denotes a **chi**meric antibody (e.g., Infliximab, Rituximab), while **"-umab"** denotes a fully h**uma**n antibody (e.g., Adalimumab). * **Pre-treatment Screening:** Before starting any TNF-α inhibitor, patients **must** be screened for **Latent Tuberculosis** (via TST or IGRA) and Hepatitis B, as these drugs can cause reactivation of these infections. * **Adverse Effects:** Increased risk of serious infections, lymphoma, and worsening of congestive heart failure (CHF).

Question 60: Which antimetabolite drug is used for the treatment of gout?

A. Allopurinol (Correct Answer)
B. Zidovudine
C. Azathioprine
D. None of the above

Explanation: **Explanation:** **Correct Answer: A. Allopurinol** Allopurinol is a structural analogue of **hypoxanthine** [1], [2]. It acts as a potent competitive inhibitor of **Xanthine Oxidase**, the enzyme responsible for converting hypoxanthine to xanthine and xanthine to uric acid [1], [2]. By inhibiting this pathway, allopurinol reduces plasma uric acid levels [2], making it the drug of choice for the chronic management of both primary and secondary gout [1], [2]. It is classified as an antimetabolite because it mimics a natural purine base to interfere with enzymatic processes [1], [2]. **Analysis of Incorrect Options:** * **B. Zidovudine (AZT):** This is a pyrimidine analogue (nucleoside reverse transcriptase inhibitor - NRTI) used in the treatment of **HIV/AIDS**. It inhibits viral DNA synthesis and has no role in uric acid metabolism. * **C. Azathioprine:** While this is an immunosuppressant antimetabolite (prodrug of 6-mercaptopurine), it is used for organ transplants and autoimmune diseases. Notably, it has a significant **drug interaction** with Allopurinol; since Allopurinol inhibits xanthine oxidase (the enzyme that degrades 6-MP), it can lead to life-threatening azathioprine toxicity. **High-Yield Clinical Pearls for NEET-PG:** * **Acute Gout Warning:** Never start Allopurinol during an acute attack of gout, as a sudden change in serum urate levels can precipitate or worsen the flare. * **HLA-B*5801:** Screening for this allele is recommended in certain populations (e.g., Han Chinese, Thai) before starting Allopurinol to prevent **Stevens-Johnson Syndrome (SJS)** or Toxic Epidermal Necrolysis (TEN). * **Febuxostat:** A newer, non-purine selective inhibitor of xanthine oxidase used in patients intolerant to Allopurinol.

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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