Analgesics and Anti-inflammatory Drugs — MCQs

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

Question 341: What is the most common adverse effect of colchicine?

A. Diarrhea (Correct Answer)
B. Peptic ulcer
C. Dyspepsia
D. Pulmonary fibrosis

Explanation: **Colchicine** is a unique anti-inflammatory agent primarily used for the management of acute gouty arthritis and prophylaxis. Its primary mechanism of action involves binding to **tubulin**, which inhibits microtubule polymerization. This disrupts leukocyte migration, chemotaxis, and phagocytosis, thereby reducing the inflammatory response to urate crystals [1]. Several of colchicine's adverse effects are produced by its inhibition of tubulin polymerization and cell mitosis [1]. **Why Diarrhea is the Correct Answer:** The most common and dose-limiting adverse effect of colchicine is **diarrhea** [2]. Because colchicine inhibits microtubule formation, it interferes with the rapid turnover of gastrointestinal mucosal cells. This leads to malabsorption and increased intestinal motility. Diarrhea, often accompanied by nausea, vomiting, and abdominal pain, occurs in approximately 80% of patients receiving full therapeutic doses. It is often considered a "warning sign" to stop the medication to avoid more systemic toxicity. **Analysis of Incorrect Options:** * **B & C (Peptic Ulcer and Dyspepsia):** While these are the hallmark side effects of **NSAIDs** (due to COX-1 inhibition and reduced protective prostaglandins), they are not the primary or most common side effects associated with colchicine. * **D (Pulmonary Fibrosis):** This is a classic side effect associated with drugs like **Amiodarone, Bleomycin, and Methotrexate**, but it is not a recognized complication of colchicine therapy. **NEET-PG High-Yield Pearls:** * **Mechanism:** Inhibits microtubule assembly by binding to tubulin. * **Acute Toxicity:** Overdose can lead to hemorrhagic gastroenteritis, nephrotoxicity, and ascending paralysis. * **Chronic Toxicity:** Long-term use can cause **agranulocytosis, aplastic anemia, and myopathy** (especially when combined with statins). * **Drug of Choice:** While NSAIDs are generally first-line for acute gout, Colchicine is the drug of choice for patients with contraindications to NSAIDs (e.g., heart failure or peptic ulcer disease).

Question 342: Which of the following is the mechanism of action of Anakinra?

A. TNF alpha antagonist
B. IL 1 antagonist (Correct Answer)
C. IL 2 antagonist
D. IL 6 antagonist

Explanation: **Explanation:** **Anakinra** is a recombinant, non-glycosylated form of the human **interleukin-1 receptor antagonist (IL-1Ra)**. It works by competitively inhibiting the binding of IL-1 (both IL-1α and IL-1β) to the Interleukin-1 type I receptor. Since IL-1 is a key pro-inflammatory cytokine that mediates cartilage degradation and bone resorption, blocking its signal is effective in treating inflammatory conditions like Rheumatoid Arthritis and Cryopyrin-Associated Periodic Syndromes (CAPS). **Analysis of Incorrect Options:** * **Option A (TNF-α Antagonists):** This group includes drugs like **Etanercept** (soluble receptor), **Infliximab**, and **Adalimumab** (monoclonal antibodies). They are first-line biological DMARDs but have a different molecular target than Anakinra. * **Option C (IL-2 Antagonists):** Drugs like **Basiliximab** and **Daclizumab** target the IL-2 receptor (CD25). These are primarily used as immunosuppressants to prevent acute organ transplant rejection. * **Option D (IL-6 Antagonists):** **Tocilizumab** and **Sarilumab** are the prototypical IL-6 receptor inhibitors used in Rheumatoid Arthritis and systemic juvenile idiopathic arthritis. **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Use:** Anakinra is used in Rheumatoid Arthritis (often when TNF inhibitors fail) and is the drug of choice for **Neonatal-Onset Multisystem Inflammatory Disease (NOMID)**. * **Administration:** It has a short half-life (~4-6 hours) and requires **daily subcutaneous injections**, which makes it less patient-friendly than other biologics. * **Side Effects:** Injection site reactions are the most common; however, it also increases the risk of serious infections. * **Contraindication:** Never combine Anakinra with TNF-α blockers due to a significantly increased risk of neutropenia and fatal infections.

Question 343: Which cyclooxygenase plays a role in maintaining gastrointestinal mucosal integrity?

A. Cyclooxygenase 1 (Correct Answer)
B. Cyclooxygenase 2
C. Cyclooxygenase 3
D. Cyclooxygenase 4

Explanation: ### Explanation **1. Why Option A (COX-1) is Correct:** Cyclooxygenase-1 (COX-1) is a **constitutive enzyme** expressed in most tissues under normal physiological conditions. It is often referred to as the "housekeeping" enzyme. In the gastrointestinal tract, COX-1 facilitates the synthesis of cytoprotective prostaglandins (specifically **PGE2 and PGI2**). These prostaglandins maintain mucosal integrity by: * Increasing the secretion of protective mucus and bicarbonate. * Enhancing mucosal blood flow. * Inhibiting gastric acid secretion. Inhibition of COX-1 by non-selective NSAIDs (like Aspirin or Ibuprofen) is the primary reason for gastric ulcers and GI bleeding. **2. Why Other Options are Incorrect:** * **Option B (COX-2):** This is primarily an **inducible enzyme** triggered by cytokines and growth factors during inflammation. While it plays a minor role in ulcer healing, its main function is mediating pain, fever, and inflammation. * **Option C (COX-3):** This is a variant of COX-1 (often called COX-1b) found predominantly in the **Central Nervous System**. It is the primary target for Paracetamol (Acetaminophen) but does not play a role in GI mucosal protection. * **Option D (COX-4):** This enzyme does not exist in human pharmacology; it is a distractor. **3. High-Yield Clinical Pearls for NEET-PG:** * **Selective COX-2 Inhibitors (Coxibs):** These drugs (e.g., Celecoxib) provide analgesia with a lower risk of GI ulcers because they spare the COX-1 enzyme. * **Aspirin Sensitivity:** Aspirin irreversibly inhibits COX-1 in platelets, leading to its anti-platelet effect (lasting 7–10 days). * **Misoprostol:** A PGE1 analog used to prevent NSAID-induced gastric ulcers by replacing the prostaglandins lost due to COX-1 inhibition. * **The "COX-2 Paradox":** While COX-2 inhibitors are GI-friendly, they may increase cardiovascular risk by upsetting the balance between Thromboxane A2 (COX-1 mediated) and Prostacyclin (COX-2 mediated).

Question 344: What is the primary mechanism of action of Aspirin?

A. Lipooxygenase activity is decreased
B. Cyclooxygenase activity is decreased (Correct Answer)
C. Phospholipase activity is affected
D. Lipooxygenase activity is increased

Explanation: ### Explanation **1. Why the Correct Answer is Right:** Aspirin (Acetylsalicylic acid) belongs to the NSAID class. Its primary mechanism is the **irreversible inhibition of the Cyclooxygenase (COX-1 and COX-2) enzymes**. Unlike other NSAIDs that bind reversibly, Aspirin covalently attaches an acetyl group to a serine residue in the active site of the COX enzyme. This prevents the conversion of arachidonic acid into Prostaglandins (mediators of pain and inflammation) and Thromboxane A2 (a potent platelet aggregator). **2. Why the Other Options are Wrong:** * **Option A & D:** Aspirin does not directly inhibit the **Lipooxygenase (LOX)** pathway. In fact, by blocking the COX pathway, arachidonic acid may be shunted toward the LOX pathway, leading to increased production of Leukotrienes. This "shunting" is the mechanism behind **Aspirin-Exacerbated Respiratory Disease (AERD)** or "Aspirin Asthma." * **Option C:** **Phospholipase A2** is the enzyme that releases arachidonic acid from membrane phospholipids. This enzyme is inhibited by **Corticosteroids**, not Aspirin. **3. High-Yield Clinical Pearls for NEET-PG:** * **Irreversible Action:** Because platelets cannot synthesize new enzymes, Aspirin’s antiplatelet effect lasts for the entire lifespan of the platelet (**7–10 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 (e.g., Influenza, Varicella) due to the risk of fulminant hepatic failure and encephalopathy. * **Therapeutic Range:** Low dose (<325 mg) is antiplatelet; intermediate dose is analgesic/antipyretic; high dose is anti-inflammatory.

Question 345: Which prostaglandin causes renal vasodilation?

A. PGD2
B. PGE2 (Correct Answer)
C. PGF2
D. All of the above

Explanation: **Explanation:** The correct answer is **PGE2**. In the kidneys, prostaglandins play a vital role in maintaining renal hemodynamics, particularly during states of decreased effective circulating volume. **1. Why PGE2 is correct:** Prostaglandin E2 (PGE2) is a potent **renal vasodilator**. It acts primarily on the EP2 and EP4 receptors to relax vascular smooth muscle. Its key physiological role is to antagonize the vasoconstrictor effects of Angiotensin II and Norepinephrine on the afferent arterioles. By maintaining vasodilation, PGE2 ensures adequate Renal Blood Flow (RBF) and Glomerular Filtration Rate (GFR). It also inhibits sodium reabsorption in the thick ascending limb and water reabsorption in the collecting ducts (acting as a "natural diuretic"). **2. Analysis of Incorrect Options:** * **PGD2:** While PGD2 has vasodilatory properties in the systemic circulation (involved in flushing and allergic responses), it is not the primary prostaglandin responsible for regulating renal hemodynamics. * **PGF2α:** This prostaglandin is primarily a **vasoconstrictor** and causes contraction of smooth muscles, including the uterus (used for postpartum hemorrhage) and bronchioles. It does not cause renal vasodilation. **3. High-Yield NEET-PG Pearls:** * **NSAIDs and the Kidney:** NSAIDs inhibit COX enzymes, blocking the production of PGE2. In patients with heart failure or CKD, this loss of compensatory vasodilation can lead to **acute renal failure** due to unopposed vasoconstriction of the afferent arteriole. * **PGI2 (Prostacyclin):** Along with PGE2, PGI2 is the other major vasodilator in the kidney. If PGI2 were an option, it would also be correct. * **Triple Whammy:** Be wary of the combination of **ACE inhibitors + Diuretics + NSAIDs**, which significantly increases the risk of acute kidney injury by reducing GFR from multiple angles.

Question 346: Which NSAID has the least anti-inflammatory action?

A. Indomethacin
B. Paracetamol (Correct Answer)
C. Ketorolac
D. Ibuprofen

Explanation: **Explanation:** The correct answer is **Paracetamol (Acetaminophen)**. **Why Paracetamol is the correct answer:** While Paracetamol is a potent analgesic and antipyretic, it possesses **negligible anti-inflammatory activity**. Its mechanism involves the inhibition of prostaglandin synthesis primarily in the Central Nervous System (CNS). In peripheral tissues, its action is neutralized by the presence of **peroxides** generated at sites of inflammation. Since it cannot effectively inhibit COX enzymes in a peroxide-rich inflammatory environment, it fails to reduce swelling or inflammation. **Analysis of Incorrect Options:** * **Indomethacin:** A potent non-selective COX inhibitor. It is one of the most powerful anti-inflammatory agents, often used for acute gout and ankylosing spondylitis. * **Ketorolac:** A pyrrolo-pyrrole derivative with very high analgesic potency (comparable to morphine for post-op pain) and significant anti-inflammatory action, though its use is limited by GI toxicity. * **Ibuprofen:** A propionic acid derivative that is a standard NSAID with effective analgesic, antipyretic, and anti-inflammatory properties. **High-Yield NEET-PG Pearls:** * **Mechanism of Action:** Paracetamol is often considered a "COX-3 inhibitor" (a variant of COX-1 found in the brain), though this remains a subject of research. * **Drug of Choice:** Paracetamol is the preferred analgesic/antipyretic in children (to avoid Reye’s syndrome caused by Aspirin) and in patients with peptic ulcers or bleeding disorders. * **Toxicity:** The toxic metabolite of Paracetamol is **NAPQI**. In overdose, it causes centrilobular hepatic necrosis. The antidote is **N-acetylcysteine (NAC)**, which replenishes glutathione stores. * **Comparison:** If the question asks for the NSAID with the **highest** analgesic potency but low anti-inflammatory action relative to its pain-killing effect, the answer is often Ketorolac. However, for **least** anti-inflammatory action overall, Paracetamol is the definitive answer.

Question 347: Which drug is used for penile erection?

A. Sildenafil
B. Apomorphine
C. Papaverine
D. All of the above (Correct Answer)

Explanation: The management of erectile dysfunction (ED) involves drugs with different mechanisms of action, ranging from oral phosphodiesterase inhibitors to injectable vasodilators and centrally acting dopamine agonists [1, 2]. * **Sildenafil (Option A):** This is a selective **PDE-5 inhibitor**. It prevents the degradation of cGMP in the corpus cavernosum, leading to smooth muscle relaxation and increased blood flow. It is the first-line oral treatment for ED [1, 3]. * **Apomorphine (Option B):** Unlike other agents, this is a **centrally acting dopamine (D2) agonist**. It acts on the paraventricular nucleus of the hypothalamus to stimulate the natural pro-erectile signals. It is typically administered sublingually. * **Papaverine (Option C):** An **opium alkaloid** that acts as a non-selective phosphodiesterase inhibitor and direct vasodilator. It is used via **intracavernosal injection** to induce an erection by directly relaxing the penile vascular smooth muscle. **Conclusion:** Since all three drugs utilize different pathways to facilitate or induce penile erection, **Option D (All of the above)** is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** 1. **Alprostadil (PGE1):** Another common drug used via the intracavernosal or intraurethral route for ED. 2. **Contraindication:** Sildenafil must never be given to patients taking **Nitrates**, as it can cause life-threatening hypotension [1]. 3. **Side Effect:** A specific side effect of Sildenafil is **blue-tinted vision (cyanopsia)** due to weak inhibition of PDE-6 in the retina. 4. **Priapism:** Papaverine carries a higher risk of priapism (prolonged, painful erection) compared to PGE1.

Question 348: Chloroquine is useful in which of the following conditions?

A. Discoid lupus erythematosus
B. Rheumatoid arthritis
C. Infectious mononucleosis
D. All of the above (Correct Answer)

Explanation: **Explanation:** Chloroquine and its derivative, Hydroxychloroquine, are 4-aminoquinolines traditionally known as antimalarials. However, they possess significant **anti-inflammatory and immunomodulatory properties**, making them versatile in various clinical scenarios. 1. **Discoid Lupus Erythematosus (DLE):** Chloroquine is a first-line systemic therapy for DLE. It works by stabilizing lysosomal membranes, inhibiting chemotaxis, and protecting the skin from UV-induced damage. It is highly effective for the cutaneous manifestations of lupus. 2. **Rheumatoid Arthritis (RA):** It is classified as a "Disease-Modifying Anti-Rheumatic Drug" (DMARD). While it is a "slow-acting" drug (taking 3–6 months for full effect), it is used in mild cases or in combination with Methotrexate to reduce joint inflammation and prevent progression. 3. **Infectious Mononucleosis:** Though less common today, Chloroquine has been used historically to control the high fever and severe pharyngeal symptoms associated with the Epstein-Barr virus (EBV) due to its non-specific anti-inflammatory effects. **Why "All of the above" is correct:** Chloroquine’s ability to interfere with antigen presentation and reduce cytokine release (IL-1, IL-6, TNF-α) allows it to be effective across these diverse autoimmune and inflammatory conditions. **High-Yield Clinical Pearls for NEET-PG:** * **Ocular Toxicity:** The most serious side effect is **"Bull’s eye maculopathy"** (retinal toxicity). Baseline and periodic fundus examinations are mandatory. * **Mechanism in Malaria:** It inhibits the biocrystallization of heme into hemozoin, leading to toxic heme accumulation within the parasite. * **Other Uses:** It is also used in Photogenic reactions, Lepra reactions (Type 2), and Extra-intestinal amoebiasis (liver abscess).

Question 349: Infliximab is:

A. CD20 antagonist
B. IL6 antagonist
C. Chimeric antibody against TNF alpha (Correct Answer)
D. Chimeric antibody against Her2-neu

Explanation: **Explanation:** **Infliximab** is a potent biological agent used primarily in the management of autoimmune conditions like Rheumatoid Arthritis, Crohn’s disease, and Ankylosing Spondylitis. It is a **chimeric monoclonal antibody** (composed of 75% human and 25% murine sequences) that binds specifically to **Tumor Necrosis Factor-alpha (TNF-α)**. By neutralizing both soluble and transmembrane forms of TNF-α, it prevents the cytokine from binding to its receptors, thereby downregulating the inflammatory cascade. **Analysis of Options:** * **Option A (CD20 antagonist):** This describes **Rituximab**. It targets CD20 receptors on B-cells and is used in Non-Hodgkin Lymphoma and refractory Rheumatoid Arthritis. * **Option B (IL-6 antagonist):** This describes **Tocilizumab** or **Sarilumab**. These drugs block the Interleukin-6 receptor and are used in systemic juvenile idiopathic arthritis and severe COVID-19. * **Option D (Chimeric antibody against Her2-neu):** This refers to **Trastuzumab** (though Trastuzumab is humanized, not chimeric). It is used specifically in Her2-positive breast cancer. **High-Yield NEET-PG Pearls:** * **Nomenclature Tip:** Monoclonal antibodies ending in **"-ximab"** are chimeric (e.g., Infliximab, Rituximab), while those ending in **"-umab"** are fully human (e.g., Adalimumab). * **Pre-treatment Screening:** Before starting TNF-α inhibitors like Infliximab, patients **must** be screened for **Latent Tuberculosis** (via PPD or IGRA) because these drugs can cause the reactivation of TB by disrupting granulomas. * **Other TNF-α Inhibitors:** Adalimumab (Human mAb), Etanercept (Fusion protein/Decoy receptor), and Certolizumab (Pegylated Fab fragment).

Question 350: Canakinumab is a monoclonal antibody against:

A. IL-1 (Correct Answer)
B. IL-2
C. IL-5
D. IL-6

Explanation: **Explanation:** **Canakinumab** is a high-affinity, human monoclonal antibody specifically directed against **Interleukin-1 beta (IL-1β)**. By binding to IL-1β, it prevents the cytokine from interacting with its receptors, thereby neutralizing the pro-inflammatory cascade. * **Why Option A is Correct:** Canakinumab belongs to the class of IL-1 inhibitors. It is primarily used in the management of **Systemic Juvenile Idiopathic Arthritis (sJIA)** and **Cryopyrin-Associated Periodic Syndromes (CAPS)**, such as Muckle-Wells syndrome, where IL-1 overproduction is the primary driver of inflammation. * **Why Other Options are Incorrect:** * **IL-2:** Targeted by drugs like **Basiliximab** and **Daclizumab** (IL-2 receptor antagonists), used mainly in transplant medicine to prevent organ rejection. * **IL-5:** Targeted by **Mepolizumab** and **Reslizumab** (while Benralizumab targets the IL-5 receptor). These are used in the treatment of severe eosinophilic asthma. * **IL-6:** Targeted by **Tocilizumab** and **Sarilumab**. These are commonly used in Rheumatoid Arthritis and were notable during COVID-19 management for cytokine storm. **High-Yield Clinical Pearls for NEET-PG:** 1. **IL-1 Inhibitor Trio:** Remember **Anakinra** (Recombinant IL-1 receptor antagonist), **Canakinumab** (Monoclonal antibody against IL-1β), and **Rilonacept** (IL-1 trap). 2. **CANTOS Trial:** Canakinumab was famously studied for reducing cardiovascular risk by lowering systemic inflammation (CRP levels), though it is not a primary indication due to cost and infection risk. 3. **Key Indication:** It is the drug of choice for **Gouty Arthritis** in patients who cannot tolerate NSAIDs or Colchicine.

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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