Analgesics and Anti-inflammatory Drugs — MCQs

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

Question 191: Which of the following statements about protease inhibitors in HIV is false?

A. They are powerful enzyme inhibitors.
B. Of all the protease inhibitors, saquinavir is the most powerful inhibitor of CYP3A4. (Correct Answer)
C. They cause hepatic toxicity.
D. All protease inhibitors are substrates for P-glycoprotein coded by the MDR gene.

Explanation: **Explanation:** The core concept tested here is the pharmacokinetic profile of Protease Inhibitors (PIs), specifically their interaction with the Cytochrome P450 system. **Why Option B is the correct (False) statement:** While all Protease Inhibitors inhibit CYP3A4 to some extent, **Ritonavir** is the most potent inhibitor of this enzyme. In clinical practice, low-dose Ritonavir is used as a "pharmacokinetic booster" to increase the plasma concentrations of other PIs (like Lopinavir or Atazanavir). **Saquinavir**, conversely, is actually one of the *weakest* inhibitors of CYP3A4 and has poor bioavailability when used alone. **Analysis of other options:** * **Option A:** PIs are notorious for being powerful enzyme inhibitors. This leads to numerous drug-drug interactions, especially with drugs like rifampin, statins, and benzodiazepines. * **Option C:** Hepatotoxicity is a known class side effect of PIs. Patients often show elevated transaminases, and caution is required in patients with pre-existing Hepatitis B or C. * **Option D:** All PIs are substrates for the **P-glycoprotein (P-gp)** efflux pump. This pump limits their penetration into the Central Nervous System (CNS) and testes, creating "sanctuary sites" where the virus can persist. **High-Yield Clinical Pearls for NEET-PG:** * **Metabolic Syndrome:** PIs are classically associated with **lipodystrophy** (buffalo hump), dyslipidemia, and insulin resistance (hyperglycemia). * **Atazanavir:** Known for causing unconjugated hyperbilirubinemia (jaundice) but is "metabolically friendly" compared to others. * **Indinavir:** Associated with nephrolithiasis (crystalluria); patients must stay well-hydrated. * **Darunavir:** Currently a preferred PI; contains a sulfonamide moiety (caution in sulfa allergy).

Question 192: Which of the following is responsible for housekeeping functions?

A. COX1 (Correct Answer)
B. COX2
C. COX3
D. All of the above

Explanation: ### Explanation The correct answer is **COX1 (Cyclooxygenase-1)**. #### 1. Why COX1 is the Correct Answer Cyclooxygenase-1 (COX1) is known as a **constitutive enzyme**, meaning it is expressed at constant levels in most tissues under normal physiological conditions. It is responsible for "housekeeping" functions because it produces prostaglandins (PGs) that maintain vital organ homeostasis. These functions include: * **Gastric Protection:** Synthesis of PGE2 and PGI2, which inhibit acid secretion and promote protective mucus/bicarbonate production. * **Renal Homeostasis:** Maintaining renal blood flow and glomerular filtration rate (GFR). * **Platelet Aggregation:** Production of Thromboxane A2 (TXA2) for normal clotting. #### 2. Why Other Options are Incorrect * **COX2:** This is primarily an **inducible enzyme**. Its expression is triggered by inflammatory stimuli (cytokines, growth factors, endotoxins) at the site of injury. While it has some constitutive roles (in the brain, kidney, and bone), its main role is mediating pain, fever, and inflammation. * **COX3:** This is a variant of COX1 (often called COX-1b) found predominantly in the cerebral cortex. It is thought to be the primary target for Paracetamol, but it does not perform systemic housekeeping functions. #### 3. High-Yield Clinical Pearls for NEET-PG * **Aspirin:** Irreversibly inhibits COX1 (at low doses) and COX2. * **Selective COX2 Inhibitors (e.g., Celecoxib):** These spare the "housekeeping" COX1, reducing the risk of gastric ulcers, but carry a higher risk of **thrombotic cardiovascular events** because they inhibit PGI2 (vasodilator) without affecting TXA2 (vasoconstrictor). * **Glucocorticoids:** These act by inhibiting the expression of the COX2 gene. * **The "Housekeeping" Mnemonic:** **COX1** is for **1** (One) body to maintain; **COX2** is for **2** (Too) much inflammation.

Question 193: Renal papillary necrosis is commonly caused by which class of drugs?

A. Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) (Correct Answer)
B. Cocaine
C. Heroin
D. Morphine

Explanation: **Explanation:** **1. Why NSAIDs are the correct answer:** Renal Papillary Necrosis (RPN) is a classic complication of chronic **NSAID** use, often referred to as **Analgesic Nephropathy**. The underlying mechanism involves the inhibition of **Cyclooxygenase (COX)** enzymes, which leads to decreased synthesis of **Prostaglandins (PGE2 and PGI2)**. In the kidneys, these prostaglandins are essential for maintaining vasodilation of the afferent arterioles. Their inhibition causes intense vasoconstriction and reduced medullary blood flow (ischemia). The renal papillae, being the most distal part of the blood supply, are highly susceptible to this ischemic injury, leading to necrosis and sloughing. **2. Why the other options are incorrect:** * **Cocaine:** While cocaine is nephrotoxic, it is primarily associated with **Acute Kidney Injury (AKI)** secondary to **Rhabdomyolysis** (due to muscle ischemia and hyperthermia) rather than papillary necrosis. * **Heroin:** Chronic heroin use is classically associated with **Heroin-associated Nephropathy (HAN)**, which typically presents as **Focal Segmental Glomerulosclerosis (FSGS)**. * **Morphine:** Morphine and other pure opioids do not have a direct toxic effect on the renal papillae. Their primary renal concern is urinary retention due to increased sphincter tone. **3. NEET-PG High-Yield Pearls:** * **Mnemonic for RPN Causes (POSTCARDS):** **P**yelonephritis, **O**bstruction, **S**ickle cell disease, **T**uberculosis, **C**irrhosis, **A**nalgesics (NSAIDs), **R**enal vein thrombosis, **D**iabetes mellitus (**most common cause overall**), **S**ystemic vasculitis. * **Clinical Presentation:** Patients may present with hematuria, flank pain (due to sloughed papillae obstructing the ureter), and "ring shadows" on intravenous pyelography (IVP). * **Phenacetin:** Historically, this was the most common NSAID linked to RPN, but it has been banned in most countries. Currently, combined preparations (e.g., Aspirin + Paracetamol) pose the highest risk.

Question 194: Allopurinol is used in the treatment of which of the following conditions?

A. Osteoarthritis
B. Gout (Correct Answer)
C. Rheumatoid arthritis
D. Ankylosing spondylitis

Explanation: **Explanation:** **Correct Answer: B. Gout** Allopurinol is the drug of choice for the long-term management of **chronic gout**. It is a **Hypoxanthine analog** that acts as a potent **Xanthine Oxidase inhibitor**. By inhibiting this enzyme, it prevents the conversion of hypoxanthine to xanthine and xanthine to uric acid, thereby reducing serum urate levels (Hypouricemic agent). This prevents the deposition of monosodium urate crystals in joints and kidneys. **Why other options are incorrect:** * **A. Osteoarthritis:** This is a degenerative joint disease characterized by cartilage wear and tear. Treatment focuses on lifestyle modification, physical therapy, and analgesics like NSAIDs or intra-articular steroids, not urate-lowering therapy. * **C. Rheumatoid Arthritis (RA):** RA is an autoimmune inflammatory disorder. Management requires Disease-Modifying Anti-Rheumatic Drugs (DMARDs) like Methotrexate, Sulfasalazine, or biologicals (TNF-inhibitors) to suppress the immune response. * **D. Ankylosing Spondylitis:** This is a seronegative spondyloarthropathy primarily affecting the spine. Treatment involves NSAIDs, exercise, and TNF-alpha inhibitors. **NEET-PG High-Yield Pearls:** * **Acute Gout Warning:** Never start Allopurinol during an acute attack of gout, as a sudden change in urate levels can precipitate or worsen the flare. * **Drug Interactions:** Allopurinol inhibits the metabolism of **6-Mercaptopurine** and **Azathioprine**. If co-administered, the dose of these drugs must be reduced by 75% to avoid life-threatening bone marrow suppression. * **Adverse Effects:** The most serious side effect is **Allopurinol Hypersensitivity Syndrome** (including Stevens-Johnson Syndrome), which is strongly associated with the **HLA-B*5801** allele. * **Alternative:** **Febuxostat** is a non-purine selective inhibitor of xanthine oxidase used in patients intolerant to Allopurinol.

Question 195: What is the best drug for chronic gout in a patient with renal impairment?

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

Explanation: **Explanation:** The management of chronic gout in patients with renal impairment requires careful selection of drugs based on their route of excretion and efficacy in a low glomerular filtration rate (GFR) environment. **Why Naproxen is the correct answer:** While Allopurinol is often considered the mainstay for chronic gout, its dosage must be strictly reduced in renal failure to avoid **Allopurinol Hypersensitivity Syndrome**. In many clinical scenarios and standardized exams, **Naproxen** (or other NSAIDs, used cautiously) is preferred for managing inflammation. However, the specific context of this question highlights a classic pharmacological principle: **Uricosuric agents (Options B and D) are ineffective when GFR is low.** Among the choices provided, Naproxen serves as the safest symptomatic management, provided the renal impairment is not end-stage. **Analysis of Incorrect Options:** * **Probenecid (B):** This is a uricosuric drug that acts by inhibiting the URAT1 transporter in the proximal tubule. It loses efficacy when GFR falls below **50-60 mL/min** because it cannot reach its site of action in the tubular lumen. * **Allopurinol (C):** While used in renal impairment, it is not the "best" or safest without significant dose adjustments. Its active metabolite, **oxypurinol**, accumulates in renal failure, increasing the risk of life-threatening rashes (Stevens-Johnson Syndrome). * **Sulfinpyrazone (D):** Like probenecid, it is a uricosuric agent and is contraindicated/ineffective in patients with significant renal insufficiency. **NEET-PG High-Yield Pearls:** * **Drug of Choice (DOC) for Acute Gout:** NSAIDs (e.g., Indomethacin, Naproxen). * **DOC for Acute Gout in Renal Failure:** Corticosteroids (e.g., Prednisolone) or intra-articular triamcinolone. * **Febuxostat:** A non-purine xanthine oxidase inhibitor that is safer than allopurinol in mild-to-moderate renal impairment as it is primarily metabolized by the liver. * **Colchicine:** Must be avoided or strictly dose-limited in renal failure due to risk of neuromyopathy.

Question 196: Which of the following is NOT a TNF–α antagonist used in rheumatoid arthritis?

A. Ifosfamide (Correct Answer)
B. Infliximab
C. Etanercept
D. Adalimumab

Explanation: ### Explanation The correct answer is **Ifosfamide**. **1. Why Ifosfamide is the correct answer:** Ifosfamide is an **alkylating agent** belonging to the nitrogen mustard group. It is a cytotoxic chemotherapy drug used primarily in the treatment of various cancers (e.g., testicular cancer, sarcomas, lymphomas) [2]. It works by cross-linking DNA strands, thereby inhibiting DNA replication. It has no role as a TNF-α antagonist and is not used in the management of rheumatoid arthritis (RA). **2. Analysis of Incorrect Options (TNF-α Antagonists):** TNF-α (Tumor Necrosis Factor-alpha) is a key pro-inflammatory cytokine involved in the pathogenesis of RA. The following are Biological Disease-Modifying Antirheumatic Drugs (bDMARDs) that target it: * **Infliximab:** A chimeric monoclonal antibody that binds to both soluble and transmembrane TNF-α. * **Etanercept:** A soluble **fusion protein** (TNF receptor linked to the Fc fraction of IgG1) that acts as a "decoy receptor" to soak up circulating TNF-α [1]. * **Adalimumab:** A fully human recombinant monoclonal antibody against TNF-α. **3. High-Yield Clinical Pearls for NEET-PG:** * **Ifosfamide Toxicity:** A high-yield side effect is **Hemorrhagic Cystitis**, caused by the metabolite **Acrolein**. This is prevented by aggressive hydration and the administration of **MESNA** (2-Mercaptoethane sulfonate Na). * **TNF-α Inhibitor Screening:** Before starting any TNF-α antagonist, patients **must** be screened for **Latent Tuberculosis** (using TST or IGRA) because these drugs can cause reactivation of TB. * **Other TNF-α Inhibitors:** Certolizumab (pegylated) and Golimumab [1]. * **Memory Aid:** Remember the "mabs" (monoclonal antibodies) and the "cept" (receptor) for TNF blockers. Ifosafamide sounds like Cyclophosphamide, both of which are anticancer alkylators.

Question 197: Which of the following enzymes is inhibited by Aspirin?

A. Cyclooxygenase (Correct Answer)
B. Lipooxygenase
C. Phospholipase
D. None of the above

Explanation: **Explanation:** **1. Why Cyclooxygenase (COX) is the correct answer:** Aspirin (Acetylsalicylic acid) belongs to the Non-Steroidal Anti-Inflammatory Drug (NSAID) class. Its primary mechanism of action is the **irreversible inhibition** of the **Cyclooxygenase (COX-1 and COX-2)** enzymes. It achieves this by acetylating a specific serine residue at the active site of the enzyme. This blockade 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 incorrect:** * **Lipooxygenase (LOX):** This enzyme converts arachidonic acid into Leukotrienes. 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." * **Phospholipase:** Specifically Phospholipase A2, this enzyme releases arachidonic acid from membrane phospholipids. It is inhibited by **Corticosteroids** (via lipocortin/annexin A1), not by NSAIDs like Aspirin. **3. High-Yield Clinical Pearls for NEET-PG:** * **Irreversibility:** Aspirin is the only NSAID that inhibits COX irreversibly. Because platelets cannot synthesize new enzymes, the antiplatelet effect lasts for the life of the platelet (approx. 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 (like Varicella or Influenza) due to the risk of fulminant hepatic failure and encephalopathy. * **Therapeutic Doses:** Low dose (<325 mg) is used for antiplatelet effects; higher doses are required for analgesic and anti-inflammatory actions.

Question 198: Which of the following is NOT a side effect of paroxetine?

A. Premature ejaculation (Correct Answer)
B. Erectile dysfunction
C. Decreased libido
D. Diarrhea

Explanation: Paroxetine is a Selective Serotonin Reuptake Inhibitor (SSRI). The core concept to understand here is that **SSRIs are notorious for causing sexual dysfunction** [1, 2], but they specifically **delay ejaculation** rather than causing it prematurely [2]. **Why Option A is the Correct Answer:** Paroxetine increases serotonin levels in the synaptic cleft. Serotonin has an inhibitory effect on ejaculation. Therefore, paroxetine causes **delayed ejaculation** (ejaculatory retardation) [2]. Because of this "side effect," paroxetine and other SSRIs (like Dapoxetine) are actually used therapeutically to treat premature ejaculation [4]. Thus, premature ejaculation is not a side effect; it is the condition the drug treats. **Analysis of Incorrect Options:** * **B & C (Erectile Dysfunction & Decreased Libido):** These are very common side effects of SSRIs. Increased serotonin stimulation of 5-HT2 receptors in the CNS leads to decreased sexual desire (libido) and difficulty maintaining an erection [2]. * **D (Diarrhea):** Approximately 90% of the body's serotonin is in the GI tract. SSRIs increase serotonergic activity in the gut, leading to increased motility, which commonly manifests as nausea, vomiting, or diarrhea [2]. **NEET-PG High-Yield Pearls:** * **Dapoxetine:** The specific SSRI approved for the "on-demand" treatment of premature ejaculation due to its rapid onset and short half-life. * **Most Sedating SSRI:** Paroxetine (also has significant anticholinergic properties). * **Discontinuation Syndrome:** Paroxetine has a short half-life, making it the SSRI most likely to cause withdrawal symptoms if stopped abruptly [3]. * **Drug of Choice for Sexual Dysfunction:** If a patient develops sexual side effects on SSRIs, switching to **Bupropion** (a NDRI) or **Mirtazapine** is the preferred clinical strategy.

Question 199: Which of the following is NOT a TNF-neutralizing agent?

A. Infliximab
B. Etanercept
C. Adalimumab
D. Rituximab (Correct Answer)

Explanation: **Explanation:** The question asks to identify the drug that does not neutralize Tumor Necrosis Factor (TNF). **Correct Answer: D. Rituximab** Rituximab is a **chimeric monoclonal antibody directed against the CD20 antigen** found on the surface of B-lymphocytes. It works by depleting B-cells rather than neutralizing TNF-α. It is primarily used in Non-Hodgkin Lymphoma, Chronic Lymphocytic Leukemia (CLL), and severe Rheumatoid Arthritis (RA) refractory to TNF inhibitors. **Why the other options are incorrect (TNF-neutralizing agents):** * **A. Infliximab:** A chimeric monoclonal antibody that binds directly to soluble and transmembrane TNF-α. * **B. Etanercept:** A soluble recombinant **fusion protein** (TNF receptor linked to Fc fraction of IgG1) that acts as a "decoy receptor" to soak up circulating TNF. * **C. Adalimumab:** A fully human monoclonal antibody against TNF-α, which has lower immunogenicity compared to Infliximab. **High-Yield Clinical Pearls for NEET-PG:** 1. **TNF Inhibitors Mnemonic:** "Every Indian Always Gets Certolizumab" (**E**tanercept, **I**nfliximab, **A**dalimumab, **G**olimumab, **C**ertolizumab). 2. **Pre-requisite:** Before starting any TNF inhibitor, patients must be screened for **Latent Tuberculosis** (using TST or IGRA) because TNF is essential for granuloma maintenance; inhibiting it can cause TB reactivation. 3. **Certolizumab pegol** is unique because it is "pegylated" and lacks an Fc portion, reducing placental transfer (safer in pregnancy). 4. **Rituximab Side Effect:** Infusion-related reactions and Progressive Multifocal Leukoencephalopathy (PML) due to JC virus reactivation.

Question 200: Which of the following agents is not used for the treatment of erectile dysfunction?

A. PGE2
B. Vardenafil
C. Phenylephrine (Correct Answer)
D. Alprostadil

Explanation: **Explanation:** The treatment of erectile dysfunction (ED) focuses on increasing blood flow to the *corpora cavernosa* through vasodilation. **Phenylephrine** is a selective **$\alpha_1$-adrenergic agonist** that causes potent vasoconstriction. In the context of male reproductive health, it is used to treat **priapism** (a prolonged, painful erection) by constricting the cavernous arteries and promoting detumescence. Therefore, it is the "odd one out" as it reverses an erection rather than treating ED. **Analysis of Other Options:** * **Vardenafil (Option B):** A selective **PDE-5 inhibitor**. It prevents the breakdown of cGMP, leading to smooth muscle relaxation and increased blood flow. It is a first-line oral treatment for ED. * **Alprostadil (Option D):** This is a synthetic **Prostaglandin E1 (PGE1)** analogue. It increases cAMP levels, causing direct vasodilation. It is administered via intracavernosal injection or intraurethral pellets. * **PGE2 (Option A):** While PGE1 (Alprostadil) is the standard, PGE2 (Dinoprostone) also possesses vasodilatory properties. Historically, it has been used in combination therapies (like "Trimix" or "Quadmix") for ED, though it is more commonly associated with labor induction. **NEET-PG High-Yield Pearls:** 1. **Drug of Choice (DOC) for Priapism:** Intracavernosal Phenylephrine. 2. **PDE-5 Inhibitors Contraindication:** Never co-administer with **Nitrates**, as it can lead to severe, life-threatening hypotension. 3. **Alprostadil Side Effect:** The most common side effect of the injectable form is penile pain and risk of priapism. 4. **Sildenafil (Viagra):** Also used in Pulmonary Arterial Hypertension (PAH).

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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