Analgesics and Anti-inflammatory Drugs — MCQs

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

Question 171: Which of the following drugs is NOT classified as a DMARD?

A. Chloroquine
B. BAL (Correct Answer)
C. Azathioprine
D. Leflunomide

Explanation: **Explanation:** The correct answer is **BAL (British Anti-Lewisite)**, also known as **Dimercaprol**. **Why BAL is the correct answer:** BAL is a **chelating agent**, not a Disease-Modifying Anti-Rheumatic Drug (DMARD). It is used primarily in the treatment of acute poisoning by heavy metals such as arsenic, mercury, and gold. It works by forming stable, non-toxic complexes with metal ions, which are then excreted in the urine. It has no role in modifying the course of autoimmune inflammatory conditions like Rheumatoid Arthritis (RA). **Why the other options are incorrect:** * **Chloroquine (and Hydroxychloroquine):** These are antimalarial drugs classified as **Non-biological DMARDs**. They are used in mild RA and Systemic Lupus Erythematosus (SLE) to stabilize lysosomal membranes and inhibit antigen presentation. * **Azathioprine:** This is an **immunosuppressant** (prodrug of 6-mercaptopurine) used as a DMARD in severe, refractory cases of RA. It acts by inhibiting purine synthesis, thereby suppressing T and B cell proliferation. * **Leflunomide:** A potent **Non-biological DMARD** that inhibits the enzyme **dihydroorotate dehydrogenase (DHODH)**, leading to decreased pyrimidine synthesis and inhibition of activated T-lymphocytes. **High-Yield Clinical Pearls for NEET-PG:** * **DMARD Classification:** Divided into **Synthetic/Non-biological** (Methotrexate, Sulfasalazine, Leflunomide, Hydroxychloroquine) and **Biological** (TNF-α inhibitors like Etanercept, Infliximab). * **Methotrexate** is the "Anchor Drug" and the first-line DMARD for Rheumatoid Arthritis. * **Leflunomide Side Effect:** It is highly teratogenic and has a very long half-life; a "Cholestyramine washout" is required if pregnancy is planned. * **BAL Contraindication:** It should not be used in **Iron or Cadmium poisoning** as the resulting complex is nephrotoxic.

Question 172: Bradykinin causes all the following except?

A. Smooth muscle contraction
B. Dilatation of blood vessels
C. Pain
D. Opsonisation (Correct Answer)

Explanation: ### Explanation **Bradykinin** is a potent inflammatory mediator and a member of the kinin system, primarily acting through B1 and B2 receptors. **Why Opsonisation is the correct answer:** Opsonisation is the process by which pathogens are marked for phagocytosis (e.g., by IgG or C3b). This is a function of the **complement system** and antibodies, not the kinin system. Bradykinin plays no role in the coating of antigens for immune recognition. **Analysis of Incorrect Options:** * **Smooth muscle contraction (A):** Bradykinin is a potent contractor of non-vascular smooth muscle, particularly in the **bronchial tree** (leading to cough/bronchoconstriction) and the **gastrointestinal tract**. * **Dilatation of blood vessels (B):** It is one of the most powerful endogenous vasodilators. It acts on endothelial cells to release Nitric Oxide (NO) and Prostacyclin ($PGI_2$), leading to decreased peripheral resistance and hypotension. * **Pain (C):** Bradykinin directly stimulates primary sensory nerve endings (nociceptors). It is one of the most potent pain-producing substances known and also sensitizes these endings to other mediators like prostaglandins. **High-Yield Clinical Pearls for NEET-PG:** * **ACE Inhibitors & Cough:** ACE (Angiotensin-Converting Enzyme) is the same enzyme as **Kininase II**, which degrades bradykinin. ACE inhibitors lead to an accumulation of bradykinin in the lungs, causing the classic side effect of a **dry cough** and, rarely, **angioedema**. * **Hereditary Angioedema:** Caused by C1 esterase inhibitor deficiency, leading to overproduction of bradykinin. **Icatibant** is a competitive B2 receptor antagonist used in its treatment. * **Triple Response:** Bradykinin can mimic the Lewis triple response (flush, flare, and wheal) by increasing capillary permeability.

Question 173: The anti-inflammatory action of corticosteroids is due to blocking of which of the following?

A. 15-lipoxygenase
B. Prostaglandin synthetase
C. Thromboxane synthetase
D. Breakdown of phospholipids (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. Breakdown of phospholipids** **Mechanism of Action:** Corticosteroids exert their potent anti-inflammatory effects primarily by inducing the synthesis of a group of proteins called **Annexins** (specifically **Lipocortin-1**). Lipocortin-1 inhibits the enzyme **Phospholipase A2 (PLA2)**. Since PLA2 is responsible for the release of arachidonic acid from membrane phospholipids, its inhibition prevents the **breakdown of phospholipids**. By blocking this initial "rate-limiting" step, corticosteroids effectively shut down both the **Cyclooxygenase (COX)** and **Lipoxygenase (LOX)** pathways, preventing the production of all eicosanoids (prostaglandins, thromboxanes, and leukotrienes). **Why other options are incorrect:** * **A. 15-lipoxygenase:** This enzyme is involved in the production of lipoxins. While corticosteroids indirectly reduce LOX products, they do not specifically target 15-LOX; they act much higher up in the inflammatory cascade. * **B. Prostaglandin synthetase (COX):** This is the primary target of **NSAIDs** (e.g., Aspirin, Ibuprofen). While steroids do reduce PG synthesis, they do so by limiting substrate availability (arachidonic acid) and inhibiting COX-2 expression, rather than direct enzyme blockade. * **C. Thromboxane synthetase:** This enzyme converts PGH2 to Thromboxane A2. Specific inhibitors of this enzyme exist (e.g., Dazoxiben), but this is not the mechanism of corticosteroids. **High-Yield Clinical Pearls for NEET-PG:** * **Dual Inhibition:** Unlike NSAIDs, corticosteroids inhibit **both** Prostaglandins (pain/inflammation) and Leukotrienes (bronchoconstriction), which is why they are superior in treating asthma. * **Genomic vs. Non-genomic:** Steroids also act by inhibiting the expression of **COX-2** and various inflammatory cytokines (IL-1, TNF-α) via the inhibition of transcription factor **NF-κB**. * **Mnemonic:** **S**teroids **S**top **S**ubstrate (Arachidonic acid) by inhibiting **P**hospholipase **A2**.

Question 174: A patient with malignancy is experiencing severe pain. Which of the following opioid analgesics can be administered via a transdermal patch for pain relief?

A. Morphine
B. Pentazocine
C. Fentanyl (Correct Answer)
D. Tramadol

Explanation: ### Explanation **Correct Option: C. Fentanyl** Fentanyl is a potent synthetic opioid agonist (approximately 80–100 times more potent than morphine). Its high **lipid solubility** and **low molecular weight** make it the ideal candidate for transdermal delivery [1]. The transdermal patch (Duragesic) provides a stable, continuous release of the drug over 72 hours, making it a gold-standard choice for managing chronic, stable malignant pain in patients who have difficulty swallowing or require long-term analgesia. **Analysis of Incorrect Options:** * **A. Morphine:** While it is the standard for cancer pain (WHO Step 3), it is relatively hydrophilic (low lipid solubility) [1]. This makes it unsuitable for effective absorption through the skin via a simple patch [2]. It is typically administered orally or intravenously. * **B. Pentazocine:** This is an opioid agonist-antagonist. It is not available in transdermal form and is generally avoided in severe malignancy pain because it has a "ceiling effect" on analgesia and can precipitate withdrawal in patients already on pure mu-agonists. * **D. Tramadol:** A weak mu-agonist and SNRI, used for moderate pain (WHO Step 2). It is administered orally or parenterally, but not via a transdermal patch. **High-Yield Clinical Pearls for NEET-PG:** * **Buprenorphine** is the only other opioid commonly used in transdermal patches (often used in chronic non-malignant pain). * **Fentanyl Patch Caution:** It is **not** for acute or postoperative pain because it takes 12–24 hours to reach therapeutic plasma concentrations. * **Fentanyl Metabolism:** It is metabolized by **CYP3A4**; inhibitors of this enzyme can increase fentanyl toxicity. * **Side Effects:** Like all opioids, it causes constipation and respiratory depression, but it is less likely to cause histamine release compared to morphine.

Question 175: All of the following are true regarding Ketorolac, EXCEPT?

A. Respiratory depression is a side effect. (Correct Answer)
B. It is more potent than Aspirin.
C. Its duration of action (VA) is 5-6 hours.
D. It is primarily used as an analgesic.

Explanation: **Explanation:** **Ketorolac** is a potent Non-Steroidal Anti-inflammatory Drug (NSAID) belonging to the pyrrolo-pyrrole group. It is unique because its analgesic efficacy is comparable to low-dose morphine, yet it lacks the side-effect profile of opioids. 1. **Why Option A is the Correct Answer (The False Statement):** Unlike opioids (e.g., Morphine), Ketorolac does **not** cause respiratory depression, sedation, or miosis. It acts by inhibiting cyclooxygenase (COX) enzymes to reduce prostaglandin synthesis, a mechanism that does not involve the brainstem respiratory centers. Therefore, respiratory depression is not a side effect of Ketorolac. 2. **Analysis of Other Options:** * **Option B:** Ketorolac is significantly **more potent than Aspirin**. While Aspirin is used for mild pain, Ketorolac is used for moderate-to-severe acute pain. * **Option C:** The **duration of action** is approximately **4–6 hours**, necessitating dosing every 6 hours when used for acute pain management. * **Option D:** It is **primarily used as an analgesic**, especially in post-operative settings. While it has anti-inflammatory properties, its systemic use is limited by its high risk of gastrointestinal toxicity and renal impairment if used long-term. **High-Yield Clinical Pearls for NEET-PG:** * **The "5-Day Rule":** Systemic Ketorolac (IM/IV/Oral) should not be used for more than **5 days** due to the high risk of peptic ulceration and renal failure. * **Opioid Sparing Effect:** It is frequently used in post-operative care to reduce the requirement for opioids. * **Topical Use:** Ketorolac 0.5% ophthalmic solution is commonly used to treat seasonal allergic conjunctivitis and post-operative ocular inflammation. * **Contraindication:** Avoid in patients with "Aspirin Triad" (Asthma, Nasal polyps, NSAID sensitivity).

Question 176: Prolonged treatment with isoniazid (INH) leads to deficiency of which vitamin?

A. Pyridoxine (Correct Answer)
B. Thiamine
C. Pantothenic acid
D. Niacin

Explanation: **Explanation:** **Why Pyridoxine (Vitamin B6) is the correct answer:** Isoniazid (INH) is a primary antitubercular drug that structurally resembles pyridoxine. It causes deficiency through two main mechanisms: 1. **Competitive Inhibition:** INH inhibits the enzyme *pyridoxine phosphokinase*, which converts pyridoxine into its active form, pyridoxal-5-phosphate (PLP). 2. **Increased Excretion:** INH reacts with PLP to form a hydrazone complex, which is rapidly excreted in the urine. PLP is a vital cofactor for the synthesis of inhibitory neurotransmitters like GABA. Its deficiency leads to **peripheral neuropathy** (paresthesia, numbness) and, in severe cases, CNS toxicity (seizures). **Why the other options are incorrect:** * **B. Thiamine (B1):** Deficiency (Wernicke-Korsakoff syndrome) is typically associated with chronic alcoholism or malnutrition, not INH therapy. * **C. Pantothenic acid (B5):** Deficiency is extremely rare and not linked to specific drug interactions like INH. * **D. Niacin (B3):** While INH can theoretically interfere with the conversion of tryptophan to niacin (potentially leading to Pellagra), the most direct and clinically significant deficiency caused by INH is Pyridoxine. **High-Yield Clinical Pearls for NEET-PG:** * **Prophylaxis:** To prevent neuropathy, **10–50 mg/day of Pyridoxine** is co-administered with INH, especially in high-risk groups (diabetics, alcoholics, pregnant women, and malnourished patients). * **Slow Acetylators:** Individuals with a genetic deficiency of the *N-acetyltransferase 2 (NAT2)* enzyme are at a significantly higher risk of INH-induced peripheral neuropathy. * **Sideroblastic Anemia:** INH can also cause this condition because PLP is a cofactor for ALA synthase, the rate-limiting enzyme in heme synthesis.

Question 177: What effect does histamine have?

A. Hypertension
B. Vasoconstriction
C. Vasodilation (Correct Answer)
D. Tachycardia

Explanation: **Explanation:** Histamine is a primary chemical mediator released from mast cells and basophils during allergic and inflammatory reactions [2]. Its cardiovascular effects are primarily mediated through **H1 and H2 receptors** [1], [3]. **Why Vasodilation is Correct:** Histamine causes profound **vasodilation** of terminal arterioles and precapillary sphincters [1]. This occurs via two mechanisms: 1. **H1 receptors:** Located on vascular endothelial cells, their activation triggers the release of **Nitric Oxide (NO)**, leading to rapid, short-lived vasodilation [3], [4]. 2. **H2 receptors:** Located directly on vascular smooth muscle cells, their activation increases cAMP, causing a more sustained vasodilatory effect [1], [3]. **Analysis of Incorrect Options:** * **A & B (Hypertension and Vasoconstriction):** These are incorrect because histamine is a potent vasodilator. The systemic vasodilation and increased capillary permeability lead to a decrease in peripheral vascular resistance, typically resulting in **hypotension**, not hypertension [1], [4]. * **D (Tachycardia):** While histamine can cause tachycardia, it is usually a **reflex response** to the hypotension (baroreceptor reflex) or a minor direct H2 effect on the heart [3]. However, the primary, direct vascular effect of histamine is vasodilation. **High-Yield Clinical Pearls for NEET-PG:** * **Triple Response of Lewis:** Intradermal injection of histamine causes a "Red spot" (local vasodilation), "Wheal" (edema due to increased permeability), and "Flare" (itching/redness due to axon reflex) [4]. * **Lewis’s Hunting Reaction:** Alternating vasodilation and vasoconstriction in response to cold (not directly histamine-mediated but often confused in exams). * **Drug of Choice:** For systemic anaphylaxis (massive histamine release), the physiological antagonist is **Adrenaline (1:1000 IM)**.

Question 178: What is the most common dose-limiting adverse effect of colchicine?

A. Sedation
B. Kidney damage
C. Diarrhea (Correct Answer)
D. Muscle paralysis

Explanation: **Colchicine** is a unique anti-inflammatory agent used primarily for the management of acute gouty arthritis and prophylaxis. Its primary mechanism involves binding to tubulin, preventing its polymerization into microtubules. This inhibits leukocyte migration, phagocytosis, and the release of inflammatory mediators [1]. **Why Diarrhea is the Correct Answer:** The most common and characteristic dose-limiting adverse effect of colchicine is **diarrhea**, often accompanied by nausea, vomiting, and abdominal pain [2]. This occurs because colchicine targets rapidly dividing cells. Since the gastrointestinal (GI) epithelium has a high turnover rate, the inhibition of mitosis by colchicine leads to acute mucosal toxicity [1]. In clinical practice, the appearance of diarrhea is often the signal to discontinue the drug to prevent more systemic toxicity [2]. **Analysis of Incorrect Options:** * **A. Sedation:** Colchicine does not cross the blood-brain barrier significantly and has no sedative properties. * **B. Kidney damage:** While colchicine is excreted renally and doses must be adjusted in renal failure to avoid toxicity, it is not primarily a nephrotoxic drug (unlike NSAIDs). * **D. Muscle paralysis:** While chronic use or high doses can cause **myopathy** and neuropathy (especially when combined with statins), it does not cause acute muscle paralysis. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism of Action:** Inhibition of microtubule assembly by binding to tubulin [1]. * **Drug of Choice:** Colchicine is the drug of choice for **Familial Mediterranean Fever (FMF)**. * **Toxicity:** Chronic toxicity can lead to bone marrow suppression (agranulocytosis/aplastic anemia) and alopecia. * **Acute Gout:** While effective, NSAIDs or corticosteroids are now often preferred over colchicine due to the high incidence of GI distress at therapeutic doses.

Question 179: Which uricosuric agent is used for acute gout in a patient with chronic renal failure?

A. Probenecid
B. Colchicine
C. Benzbromarone (Correct Answer)
D. Aspirin

Explanation: ### Explanation **Correct Answer: C. Benzbromarone** **Why Benzbromarone is correct:** Benzbromarone is a potent uricosuric agent that inhibits the URAT1 transporter in the proximal tubule, increasing uric acid excretion. Unlike other uricosurics, it is unique because it **retains its efficacy in patients with moderate-to-severe chronic renal failure (CRF)**, even when the Glomerular Filtration Rate (GFR) is as low as 20 ml/min. While it is primarily used for chronic management, it is the preferred uricosuric choice in the context of renal impairment. **Analysis of Incorrect Options:** * **A. Probenecid:** This is a classic uricosuric, but it **loses efficacy** when the GFR falls below 50–60 ml/min. Therefore, it is ineffective in patients with significant chronic renal failure. * **B. Colchicine:** While colchicine is a first-line drug for *acute* gout attacks, it is **not a uricosuric agent** (it does not increase uric acid excretion). Furthermore, its dose must be strictly reduced in renal failure to avoid toxicity (neuromyopathy). * **C. Aspirin:** In low doses, aspirin actually **inhibits** uric acid excretion (causing hyperuricemia) and is contraindicated in gout. High-dose aspirin is uricosuric but is rarely used due to toxicity. **High-Yield NEET-PG Pearls:** 1. **Uricosuric of Choice in Renal Failure:** Benzbromarone (effective down to GFR 20 ml/min). 2. **The "Aspirin Paradox":** Low-dose aspirin (1–2g/day) causes uric acid retention; high-dose aspirin (>5g/day) is uricosuric. 3. **Lesinurad:** A newer URAT1 inhibitor used as adjunct therapy with Xanthine Oxidase Inhibitors. 4. **Hepatotoxicity:** The main clinical concern with Benzbromarone is potential hepatotoxicity, requiring periodic liver function monitoring.

Question 180: Which of the following statements is false regarding Leflunomide?

A. Used in the treatment of Rheumatoid arthritis.
B. Acts by inhibiting IMP dehydrogenase enzyme. (Correct Answer)
C. Inhibits proliferation of T and B cells.
D. It is contraindicated in pregnancy.

Explanation: ### Explanation **Leflunomide** is a Disease-Modifying Antirheumatic Drug (DMARD) used primarily in the management of Rheumatoid Arthritis. **Why Option B is the correct (False) statement:** Leflunomide is a prodrug that is converted into its active metabolite, **A77 1726 (Teriflunomide)**. This metabolite acts by inhibiting **Dihydroorotate Dehydrogenase (DHODH)**, a key mitochondrial enzyme in the *de novo* pyrimidine synthesis pathway. It does **not** inhibit IMP dehydrogenase; IMP dehydrogenase is the target of **Mycophenolate Mofetil**, which inhibits *de novo* purine synthesis. **Analysis of other options:** * **Option A:** It is a first-line DMARD used for **Rheumatoid Arthritis**, often as an alternative to Methotrexate. * **Option C:** By inhibiting pyrimidine synthesis, it arrests the cell cycle in the G1 phase. Since T and B lymphocytes rely heavily on *de novo* synthesis for expansion, it effectively **inhibits the proliferation of T and B cells**, exerting an immunosuppressive effect. * **Option D:** Leflunomide is highly **teratogenic** and is contraindicated in pregnancy (Pregnancy Category X). Due to its long half-life (approx. 2 weeks), a "Cholestyramine washout" procedure is required to rapidly clear the drug from the body if a patient wishes to become pregnant. ### High-Yield Clinical Pearls for NEET-PG: * **Mechanism:** Inhibits Dihydroorotate Dehydrogenase → ↓ Pyrimidine synthesis. * **Side Effects:** Hepatotoxicity (monitor LFTs), diarrhea, hypertension, and alopecia. * **Washout:** Cholestyramine is used to enhance fecal excretion because the drug undergoes extensive enterohepatic circulation. * **Comparison:** Remember: **L**eflunomide = **P**yrimidines; **M**ycophenolate = **P**urines.

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