Analgesics and Anti-inflammatory Drugs — MCQs

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

Question 311: Long-term use of aspirin in rheumatoid arthritis is limited by its propensity to cause which of the following?

A. Metabolic acidosis
B. Hypersensitivity reactions
C. Gastric mucosal damage (Correct Answer)
D. Salicylism

Explanation: ### Explanation **Correct Answer: C. Gastric mucosal damage** **Mechanism of Action:** Aspirin (Acetylsalicylic acid) is a non-selective inhibitor of the **Cyclooxygenase (COX)** enzymes [3]. In the management of Rheumatoid Arthritis (RA), high anti-inflammatory doses are required [2]. Aspirin inhibits **COX-1**, which is responsible for synthesizing cytoprotective prostaglandins ($PGE_2$ and $PGI_2$) in the gastric mucosa [3]. These prostaglandins normally inhibit gastric acid secretion and promote mucus/bicarbonate production. Their depletion leads to increased acid damage, erosions, and peptic ulcers, making gastric intolerance the most common dose-limiting side effect in long-term therapy [1]. **Analysis of Incorrect Options:** * **A. Metabolic acidosis:** This is a feature of **acute salicylate poisoning** (toxic doses), not typical long-term therapeutic use. In adults, it is usually preceded by respiratory alkalosis. * **B. Hypersensitivity reactions:** While serious (e.g., Aspirin-Exacerbated Respiratory Disease), these are idiosyncratic and occur in a small percentage of the population, rather than being a dose-dependent limitation for most RA patients [2]. * **D. Salicylism:** This is a syndrome of mild toxicity (tinnitus, dizziness, headache). While it occurs with high doses, gastric distress usually manifests earlier and more frequently in chronic management [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Zero-order kinetics:** At anti-inflammatory doses (high doses), aspirin follows capacity-limited elimination. * **Samter’s Triad:** Aspirin sensitivity, Bronchial Asthma, and Nasal polyps. * **Reye’s Syndrome:** Aspirin is contraindicated in children with viral infections (Varicella/Influenza) due to the risk of hepatic encephalopathy. * **Anti-platelet effect:** Occurs at low doses (75–150 mg) via irreversible inhibition of COX-1 in platelets (thromboxane $A_2$ reduction) [3].

Question 312: Which of the NSAIDs can be administered via the parenteral route?

A. Ibuprofen
B. Ketorolac (Correct Answer)
C. Naproxen
D. Fenoprofen

Explanation: **Explanation:** **Ketorolac** is a potent NSAID primarily used for its high analgesic efficacy, which is comparable to low-dose morphine. It is the most commonly used NSAID for the management of acute, moderate-to-severe postoperative pain via the **parenteral route (IM/IV)**. While it is also available in oral and ophthalmic forms, its systemic use is strictly limited to a maximum of **5 days** due to a high risk of gastrointestinal bleeding and renal toxicity. **Analysis of Options:** * **Ketorolac (Correct):** It is specifically designed for short-term parenteral use to bypass the first-pass metabolism and provide rapid onset of action in acute settings. * **Ibuprofen:** While an IV formulation (Caldolor) exists globally, in the context of standard medical examinations and traditional pharmacology, it is primarily recognized as an **oral** propionic acid derivative. * **Naproxen:** This is a long-acting NSAID used mainly for chronic inflammatory conditions like rheumatoid arthritis; it is administered **orally**. * **Fenoprofen:** Another propionic acid derivative used for arthritis and mild pain, available only in **oral** formulations. **High-Yield Clinical Pearls for NEET-PG:** * **Other Parenteral NSAIDs:** Apart from Ketorolac, **Diclofenac** and **Parecoxib** (a prodrug of Valdecoxib) are also available for parenteral administration. * **Topical/Ophthalmic Use:** Ketorolac is frequently used as 0.5% ophthalmic drops for seasonal allergic conjunctivitis and post-cataract surgery inflammation. * **Key Contraindication:** Avoid Ketorolac in patients with renal impairment or those at high risk of peptic ulcer disease.

Question 313: Muscular rigidity caused by opioids is due to agonistic effect on which receptor?

A. Mu (Correct Answer)
B. Kappa
C. Delta
D. Sigma

Explanation: **Explanation:** **1. Why Mu (μ) is Correct:** Opioid-induced muscle rigidity (specifically "wooden chest syndrome") is a well-known side effect primarily associated with high-dose, rapid intravenous administration of potent lipophilic opioids like **Fentanyl, Sufentanil, and Remifentanil** [1]. This effect is mediated by **Mu (μ) receptors** located in the **striatum** and the **substantia nigra**. Activation of these receptors modulates GABAergic and dopaminergic pathways, leading to increased motor neuron output and skeletal muscle stiffness. This is clinically significant because it can interfere with bag-mask ventilation during anesthesia induction. **2. Why Other Options are Incorrect:** * **Kappa (κ):** These receptors are primarily associated with spinal analgesia, miosis, and **dysphoria/hallucinations**. They do not play a significant role in systemic muscular rigidity. * **Delta (δ):** These receptors contribute to supraspinal/spinal analgesia and may modulate emotional responses. While they share some properties with Mu receptors, they are not the primary mediators of motor rigidity. * **Sigma (σ):** Formerly classified as opioid receptors, they are now considered non-opioid binding sites. They are associated with psychotomimetic effects (hallucinations) and mydriasis, but not opioid-induced rigidity. **3. High-Yield Clinical Pearls for NEET-PG:** * **Management:** Opioid-induced rigidity is best managed with **Neuromuscular Blocking Agents (NMBAs)** like Succinylcholine or Vecuronium. Opioid antagonists like **Naloxone** can also reverse it but will also negate the analgesic effect. * **Wooden Chest Syndrome:** Specifically refers to the rigidity of thoracic and abdominal muscles, making ventilation nearly impossible. * **Receptor Mnemonic:** * **Mu:** Analgesia, Respiratory depression, **Rigidity**, Constipation, Euphoria. * **Kappa:** Analgesia, **Dysphoria**, Miosis.

Question 314: Which drugs inhibit the formation of IL-2?

A. Cycloserine (Correct Answer)
B. Cyclosporine
C. OKT-3
D. Tacrolimus

Explanation: **Explanation** The question asks for the drug that inhibits the **formation** (synthesis) of Interleukin-2 (IL-2). **1. Why Cyclosporine is the Correct Answer:** Cyclosporine is a **Calcineurin inhibitor**. Under normal physiological conditions, an increase in intracellular calcium activates calcineurin, a phosphatase. Calcineurin then dephosphorylates the **Nuclear Factor of Activated T-cells (NFAT)**, allowing it to enter the nucleus and promote the transcription of the **IL-2 gene**. By inhibiting calcineurin, Cyclosporine prevents the dephosphorylation of NFAT, thereby blocking the synthesis (formation) of IL-2. This leads to a decrease in T-cell proliferation. **2. Analysis of Incorrect Options:** * **Cycloserine (Option A):** This is an antitubercular drug (second-line) that inhibits bacterial cell wall synthesis by acting as an analog of D-alanine. It has no role in IL-2 inhibition. * **OKT-3 (Option C):** This is a monoclonal antibody against the **CD3 receptor** on T-cells. It works by depleting T-cells or causing TCR internalization, rather than specifically inhibiting the formation of IL-2. * **Tacrolimus (Option D):** While Tacrolimus is also a calcineurin inhibitor and *does* inhibit IL-2 formation, **Cyclosporine** is the classic textbook answer for this specific mechanism in competitive exams unless multiple options are allowed. (Note: In many clinical contexts, both B and D are correct; however, Cyclosporine is the prototype). **3. High-Yield Clinical Pearls for NEET-PG:** * **Cyclosporine Side Effects:** Nephrotoxicity (most common), Gingival Hyperplasia, Hirsutism, and Hypertension. * **Tacrolimus Side Effects:** Similar to Cyclosporine but causes **Alopecia** (instead of hirsutism) and is more likely to cause **Post-transplant Diabetes Mellitus (PTDM)**. * **Sirolimus (Rapamycin):** Unlike the above, it inhibits the **response** to IL-2 (by inhibiting mTOR) rather than its formation.

Question 315: Which of the following is the longest-acting NSAID?

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

Explanation: **Explanation:** The correct answer is **Piroxicam**. The duration of action of an NSAID is primarily determined by its **plasma half-life ($t_{1/2}$)**. Piroxicam belongs to the **Oxicam** derivative class and is characterized by an exceptionally long half-life of approximately **45–50 hours**. This pharmacological profile allows for **once-daily dosing**, which significantly improves patient compliance in chronic conditions like rheumatoid arthritis and osteoarthritis. **Analysis of Incorrect Options:** * **Aspirin:** It has a very short plasma half-life (approx. 15–20 minutes) because it is rapidly hydrolyzed to salicylic acid. Even its active metabolite, salicylate, has a dose-dependent half-life (3–15 hours), which is much shorter than Piroxicam. * **Ibuprofen:** A propionic acid derivative with a short half-life of about **2 hours**. It requires frequent dosing (3–4 times daily) to maintain therapeutic levels. * **Acetaminophen (Paracetamol):** While technically an antipyretic-analgesic with weak anti-inflammatory action, its half-life is also short, typically **2–3 hours**. **High-Yield Clinical Pearls for NEET-PG:** * **Longest-acting NSAID:** Piroxicam (Half-life ~50 hours). * **Shortest-acting NSAID:** Aspirin or Diclofenac (Half-life ~1–2 hours). * **Oxicam class:** Includes Tenoxicam (even longer half-life than Piroxicam, ~70 hours, but Piroxicam is the standard exam answer) and Meloxicam (preferential COX-2 inhibitor). * **Side Effect Profile:** Due to its long half-life and enterohepatic recirculation, Piroxicam is associated with a higher risk of **gastric mucosal ulceration** and GI bleeding compared to shorter-acting agents.

Question 316: Leflunomide is used in the treatment of which condition?

A. Rheumatoid arthritis (Correct Answer)
B. Dermatomyositis
C. Bony metastasis
D. Postmenopausal osteoporosis

Explanation: **Explanation:** **Leflunomide** is a Disease-Modifying Antirheumatic Drug (DMARD) primarily used in the management of **Rheumatoid Arthritis (RA)**. **Why Option A is correct:** Leflunomide is a prodrug that is converted into its active metabolite, **A77 1726**. Its primary mechanism of action is the inhibition of the enzyme **Dihydroorotate Dehydrogenase (DHODH)**. This enzyme is crucial for the *de novo* synthesis of pyrimidines. Since activated T-lymphocytes depend on *de novo* synthesis for proliferation (rather than the salvage pathway), Leflunomide effectively inhibits T-cell expansion and the subsequent inflammatory response in RA. **Why incorrect options are wrong:** * **B. Dermatomyositis:** While immunosuppressants are used, the first-line treatments are typically corticosteroids and conventional DMARDs like Methotrexate or Azathioprine. Leflunomide is not the standard of care. * **C. Bony metastasis:** This is managed with bisphosphonates (like Zoledronate), Denosumab, or radiotherapy to prevent skeletal-related events. * **D. Postmenopausal osteoporosis:** This is treated with Bisphosphonates, SERMs (Raloxifene), or Teriparatide to increase bone mineral density. **High-Yield Clinical Pearls for NEET-PG:** * **Loading Dose:** It has a very long half-life (approx. 2 weeks); hence, a loading dose was traditionally used (though often skipped now to reduce toxicity). * **Washout Procedure:** If a patient experiences toxicity or plans pregnancy, **Cholestyramine** is administered to enhance drug elimination via biliary interruption. * **Side Effects:** Hepatotoxicity (monitor LFTs), diarrhea, alopecia, and it is highly **teratogenic** (Category X). * **Comparison:** Its efficacy in RA is considered comparable to Methotrexate.

Question 317: What is the most important side effect of aspirin?

A. Gastritis (Correct Answer)
B. Edema
C. Kidney damage
D. Hypersensitivity

Explanation: **Explanation:** **Aspirin (Acetylsalicylic acid)** is a non-selective, irreversible inhibitor of Cyclooxygenase (COX-1 and COX-2) enzymes. **Why Gastritis is the correct answer:** The most frequent and clinically significant side effect of aspirin is **gastric mucosal damage (Gastritis/Peptic Ulcers)**. This occurs via two mechanisms: 1. **Systemic effect:** Inhibition of COX-1 reduces the synthesis of protective prostaglandins (PGE2 and PGI2), which are essential for maintaining the gastric mucosal barrier, secreting bicarbonate, and regulating blood flow. 2. **Local effect:** Aspirin is an organic acid; it causes direct chemical irritation to the gastric epithelium and can lead to "ion trapping" within mucosal cells, causing cellular damage. **Analysis of Incorrect Options:** * **B. Edema:** While NSAIDs can cause sodium and water retention by inhibiting renal prostaglandins, this is less common with aspirin compared to drugs like Piroxicam or Indomethacin. * **C. Kidney damage:** Chronic use can lead to analgesic nephropathy (papillary necrosis), but this is typically a long-term complication rather than the "most important" or most common acute side effect. * **D. Hypersensitivity:** This manifests as "Aspirin-exacerbated respiratory disease" (Aspirin Asthma) due to a shift in arachidonic acid metabolism toward the leukotriene pathway. While serious, it occurs only in susceptible individuals (approx. 10% of asthmatics). **High-Yield Clinical Pearls for NEET-PG:** * **Reye’s Syndrome:** Aspirin is contraindicated in children with viral infections (Varicella/Influenza) due to the risk of hepatic encephalopathy. * **Salicylism:** Toxicity presents with **Tinnitus** (earliest sign), vertigo, and respiratory alkalosis. * **Antiplatelet action:** Aspirin irreversibly inhibits COX-1 in platelets for their entire lifespan (8–11 days). * **Zero-order kinetics:** Aspirin follows zero-order elimination at high/toxic doses.

Question 318: Rofecoxib as compared to indomethacin is:

A. Less likely to cause gastric ulcer and their complications (Correct Answer)
B. Likely to be more effective in rheumatoid arthritis
C. Not likely to produce renal complications
D. All of the above

Explanation: The core concept behind this question is the **selectivity of COX inhibition**. **1. Why Option A is correct:** Indomethacin is a non-selective NSAID that inhibits both COX-1 and COX-2 enzymes. COX-1 is "constitutive" and responsible for producing cytoprotective prostaglandins ($PGE_2$ and $PGI_2$) in the gastric mucosa. Inhibiting COX-1 leads to gastric erosions and ulcers. **Rofecoxib** is a **selective COX-2 inhibitor** [1, 3]. Since COX-2 is primarily induced at sites of inflammation, sparing COX-1 allows the gastric mucosal barrier to remain intact, significantly reducing the risk of GI ulcers and bleeding compared to non-selective agents like indomethacin [1, 3]. **2. Why other options are incorrect:** * **Option B:** Selective COX-2 inhibitors are **equally effective**, but not superior, to non-selective NSAIDs in managing pain and inflammation in rheumatoid arthritis. Their advantage is safety (GI profile), not increased efficacy [1, 3]. * **Option C:** Both COX-1 and COX-2 are expressed in the kidneys. Therefore, selective COX-2 inhibitors like Rofecoxib **can still cause renal complications** (e.g., edema, hypertension, and renal failure) similar to traditional NSAIDs [1, 2]. **High-Yield Clinical Pearls for NEET-PG:** * **The "Coxib" Paradox:** While Rofecoxib is GI-friendly, it was withdrawn globally (VIGOR study) because it increases the risk of **myocardial infarction and stroke** [1, 2, 3]. This is due to the suppression of vascular $PGI_2$ (vasodilator/anti-aggregatory) without affecting Thromboxane $A_2$ (vasoconstrictor/pro-aggregatory). * **Drug of Choice:** Indomethacin remains the drug of choice for **Ankylosing Spondylitis** and **Patent Ductus Arteriosus (PDA)**. * **Key Contraindication:** Avoid selective COX-2 inhibitors in patients with established ischemic heart disease [2, 3].

Question 319: Which of the following describes the action of allopurinol?

A. Inhibits metabolism of purines to uric acid (Correct Answer)
B. Interferes with cytokine production
C. Inhibits uric acid reabsorption
D. Inhibits prostaglandin biosynthesis

Explanation: **Explanation:** Allopurinol is the drug of choice for the long-term management of chronic gout. It is a **hypouricemic agent** that acts as a structural analog of hypoxanthine. **1. Why Option A is Correct:** Allopurinol acts by inhibiting the enzyme **Xanthine Oxidase**. This enzyme is responsible for the sequential oxidation of hypoxanthine to xanthine, and xanthine to **uric acid** (the final product of purine metabolism). By inhibiting this pathway, allopurinol reduces the plasma concentration and urinary excretion of uric acid, thereby preventing the formation of urate crystals in joints and kidneys. **2. Why Other Options are Incorrect:** * **Option B:** Interfering with cytokine production (like TNF-α) is the mechanism of Biological DMARDs (e.g., Etanercept) used in Rheumatoid Arthritis, not gout. * **Option C:** Inhibiting uric acid reabsorption is the mechanism of **Uricosuric drugs** like **Probenecid** and Sulfinpyrazone, which act on the URAT-1 transporter in the proximal tubule. * **Option D:** Inhibiting prostaglandin biosynthesis is the mechanism of **NSAIDs** (e.g., Indomethacin, Naproxen), which are used to treat *acute* gouty attacks, not for chronic uric acid lowering. **High-Yield Clinical Pearls for NEET-PG:** * **Active Metabolite:** Allopurinol is converted by xanthine oxidase into **Alloxanthine (Oxypurinol)**, which is a long-acting non-competitive inhibitor of the same enzyme. * **Drug Interaction:** Since 6-Mercaptopurine and Azathioprine are metabolized by xanthine oxidase, their doses must be reduced by 50-75% if given with allopurinol to avoid toxicity. * **Acute Exacerbation:** Allopurinol should **never** be started during an acute attack of gout, as a sudden drop in urate levels can mobilize crystals and worsen the inflammation. * **HLA Association:** Screening for **HLA-B*5801** is recommended in certain populations to prevent severe hypersensitivity reactions (Stevens-Johnson Syndrome).

Question 320: Which of the following opioid analgesics acts primarily through mu opioid receptors?

A. Pentazocine (Correct Answer)
B. Methadone
C. Buprenorphine
D. Pethidine

Explanation: The question asks for an opioid that acts **primarily** through mu (μ) receptors. However, there appears to be a discrepancy in the provided key: **Pentazocine** is actually a **kappa (κ) receptor agonist** and a weak mu (μ) receptor antagonist/partial agonist. In standard pharmacological classification, **Methadone** and **Pethidine** are pure mu-agonists [1], while **Buprenorphine** is a partial mu-agonist [1]. If we follow the provided key (A), it is important to note that Pentazocine is the prototype of **agonist-antagonist** opioids. Pentazocine (Correct per key): It acts as an agonist at **kappa (κ) receptors** (mediating spinal analgesia and dysphoria) and has weak antagonistic or partial agonistic activity at **mu (μ) receptors**. It is unique because it can precipitate withdrawal in opioid-dependent individuals. **Methadone (Incorrect):** A potent, long-acting **pure mu-receptor agonist** [1]. It is primarily used in the management of opioid withdrawal and maintenance therapy due to its long half-life and minimal withdrawal symptoms. **Buprenorphine (Incorrect):** A **partial mu-agonist** and kappa-antagonist. It has a high affinity for mu receptors but low intrinsic activity (ceiling effect for respiratory depression) [1]. **Pethidine (Meperidine) (Incorrect):** A **pure mu-agonist** [1]. It is notable for its metabolite, *normeperidine*, which can cause seizures, and its lack of miosis (it causes mydriasis due to atropine-like action). **High-Yield Clinical Pearls for NEET-PG:** 1. **Pentazocine Side Effects:** Characterized by "psychotomimetic" effects (hallucinations, dysphoria) due to kappa stimulation. 2. **Pethidine:** Preferred in biliary colic (less sphincter of Oddi spasm than Morphine) and for shivering. 3. **Buprenorphine:** Used in "Office-based" opioid detoxification; its effects are not easily reversed by Naloxone due to slow receptor dissociation [1].

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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