Analgesics and Anti-inflammatory Drugs — MCQs

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

Question 71: Allopurinol is used in the treatment of which condition?

A. Rheumatoid arthritis
B. Psoriatic arthritis
C. Gouty arthritis (Correct Answer)
D. Polyserositis

Explanation: **Explanation:** **Correct Answer: C. Gouty arthritis** 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. It works by inhibiting the enzyme **Xanthine Oxidase**, which is responsible for converting hypoxanthine to xanthine and xanthine to uric acid. By blocking this pathway, allopurinol effectively lowers serum uric acid levels, preventing the formation and deposition of urate crystals in joints. **Why other options are incorrect:** * **A & B (Rheumatoid and Psoriatic Arthritis):** These are autoimmune inflammatory conditions. They are primarily managed with Disease-Modifying Anti-Rheumatic Drugs (DMARDs) like Methotrexate or biological agents (TNF inhibitors), not uric acid-lowering drugs. * **D (Polyserositis):** This refers to general inflammation of serous membranes (pleura, pericardium, peritoneum). It is often a feature of systemic diseases like SLE or Familial Mediterranean Fever (FMF), where Colchicine—not Allopurinol—is used for prophylaxis. **High-Yield Clinical Pearls for NEET-PG:** 1. **Acute Gout Warning:** Never start Allopurinol during an acute attack of gout, as a sudden drop in serum urate can mobilize crystals and worsen the inflammation. 2. **Drug Interactions:** Allopurinol inhibits the metabolism of **6-Mercaptopurine (6-MP)** and **Azathioprine**. If co-administered, the dose of these drugs must be reduced to 1/4th to avoid life-threatening toxicity. 3. **Hypersensitivity:** Watch for **HLA-B*5801** allele testing in certain populations to prevent Stevens-Johnson Syndrome (SJS) associated with Allopurinol. 4. **Febuxostat:** A non-purine selective inhibitor of Xanthine Oxidase used if Allopurinol is not tolerated.

Question 72: Which of the following statements about aspirin is TRUE?

A. In an afebrile patient, acute overdose of aspirin produces hypothermia.
B. Aspirin suppresses flushing associated with a large dose of nicotinic acid. (Correct Answer)
C. Aspirin therapy prevents granulomatous lesions and cardiac complications of acute rheumatic fever.
D. Long-term aspirin therapy increases the risk of developing colon cancer.

Explanation: **Explanation:** **Correct Answer: B. Aspirin suppresses flushing associated with a large dose of nicotinic acid.** Nicotinic acid (Niacin) triggers the release of **Prostaglandin D2 (PGD2)** in the skin, which causes intense cutaneous vasodilation and flushing. As a non-selective COX inhibitor, Aspirin inhibits prostaglandin synthesis. Taking 325 mg of aspirin 30 minutes before niacin administration effectively blunts this side effect, improving patient compliance. **Analysis of Incorrect Options:** * **Option A:** In acute aspirin overdose (salicylism), aspirin uncouples oxidative phosphorylation. This leads to increased metabolic rate and heat production, resulting in **hyperpyrexia** (high fever), not hypothermia, especially in children. * **Option C:** While aspirin is excellent for symptomatic relief of joint pain and swelling in acute rheumatic fever, it **does not** prevent the progression of valvular heart disease (carditis) or the formation of Aschoff bodies (granulomatous lesions). Only corticosteroids or antibiotics (for the underlying infection) impact the disease course. * **Option D:** Long-term use of low-dose aspirin is actually associated with a **decreased risk** of colorectal cancer. It is believed to inhibit the COX-2 enzyme, which is overexpressed in many adenomas and colon cancer cells. **High-Yield NEET-PG Pearls:** * **Zero-order kinetics:** Aspirin follows first-order kinetics at low doses but shifts to zero-order (saturation) kinetics at anti-inflammatory/toxic doses. * **Reye’s Syndrome:** Avoid aspirin in children with viral infections (Varicella/Influenza) due to the risk of hepatic encephalopathy and fatty liver. * **Aspirin Excretion:** In toxicity, urinary alkalinization (using Sodium Bicarbonate) enhances aspirin excretion by trapping the ionized form in the renal tubules.

Question 73: Which of the following drugs causes irreversible inhibition of cyclooxygenase?

A. Naproxen
B. Aspirin (Correct Answer)
C. Indomethacin
D. Acetaminophen

Explanation: **Explanation:** **1. Why Aspirin is the Correct Answer:** Aspirin (Acetylsalicylic acid) is unique among Non-Steroidal Anti-inflammatory Drugs (NSAIDs) because it causes **irreversible inhibition** of the cyclooxygenase (COX-1 and COX-2) enzymes. It achieves this by covalently attaching an **acetyl group** to a specific serine residue (Serine 529 in COX-1) at the active site of the enzyme. Since platelets cannot synthesize new proteins (as they lack a nucleus), the COX enzyme remains inhibited for the entire lifespan of the platelet (approx. 7–10 days). This is the pharmacological basis for its use as an antiplatelet agent. **2. Why the Other Options are Incorrect:** * **A. Naproxen & C. Indomethacin:** These are traditional NSAIDs (Propionic acid and Indole derivatives, respectively). They inhibit COX enzymes through **reversible, competitive inhibition**. Once the drug concentration in the blood drops, the enzyme activity returns to normal. * **D. Acetaminophen (Paracetamol):** This drug is a poor inhibitor of COX in peripheral tissues (hence its lack of significant anti-inflammatory activity). It acts primarily in the CNS and its inhibition is **reversible**. **3. High-Yield Clinical Pearls for NEET-PG:** * **Low-dose Aspirin (75–150 mg):** Selectively inhibits COX-1, leading to decreased Thromboxane A2 (TXA2) production, providing a cardioprotective effect. * **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. * **Aspirin Triad (Samter’s Triad):** Asthma, Nasal polyps, and Aspirin sensitivity.

Question 74: Which one of the following is aspirin?

A. Methyl salicylate
B. Para–aminobenzoic acid
C. Para–aminosalicylic acid
D. Acetyl salicylic acid (Correct Answer)

Explanation: **Explanation:** **Aspirin** is chemically known as **Acetylsalicylic acid**. It is a salicylate derivative formed by the acetylation of salicylic acid. This chemical modification is crucial because it allows aspirin to **irreversibly inhibit** the cyclooxygenase (COX-1 and COX-2) enzymes by transferring its acetyl group to a serine residue at the active site. This distinguishes it from other NSAIDs, which are generally reversible inhibitors. **Analysis of Incorrect Options:** * **A. Methyl salicylate:** Also known as "Oil of Wintergreen," this is a topical counter-irritant used in liniments and ointments for muscle pain. It is too toxic for systemic (oral) use. * **B. Para-aminobenzoic acid (PABA):** This is a precursor in bacterial folic acid synthesis. It is clinically relevant as the substrate that Sulfonamides compete with, but it has no analgesic properties. * **C. Para-aminosalicylic acid (PAS):** This is a second-line antitubercular drug (anti-mycobacterial). While it is a salicylate derivative, it is used specifically for TB and not as a standard analgesic. **Clinical Pearls for NEET-PG:** * **Mechanism:** Irreversible inhibition of COX; inhibits Thromboxane A2 (TXA2) synthesis in platelets for their entire lifespan (8–11 days). * **Zero-order Kinetics:** Aspirin follows zero-order elimination at high/toxic doses (salicylism). * **Reye’s Syndrome:** Aspirin is contraindicated in children with viral infections (e.g., influenza, chickenpox) due to the risk of hepatic encephalopathy and fatty liver. * **Anti-platelet Dose:** Low doses (75–150 mg/day) are used for cardioprotection.

Question 75: Established routes of administration of morphine include:

A. Rectal
B. Intravenous (IV)
C. Intramuscular (IM)
D. All of these (Correct Answer)

Explanation: **Explanation:** Morphine is the prototype opioid analgesic and is characterized by its versatile pharmacokinetic profile, allowing for multiple routes of administration depending on the clinical urgency and patient condition. 1. **Intravenous (IV):** This is the preferred route in emergency settings (e.g., Myocardial Infarction or acute pulmonary edema) because it provides the most rapid onset of action and allows for precise titration. 2. **Intramuscular (IM) / Subcutaneous (SC):** These are standard parenteral routes for managing postoperative pain or chronic severe pain when IV access is not necessary. 3. **Rectal:** Morphine can be administered via suppositories. This route is particularly useful in palliative care or for patients with "nothing by mouth" (NPO) status, severe nausea, or vomiting, as it bypasses a portion of the first-pass metabolism. **Why "All of these" is correct:** Morphine is highly lipid-soluble and can be absorbed through various mucosal and tissue interfaces. While the oral route is common, it undergoes extensive **first-pass metabolism** (bioavailability ~25%). Therefore, parenteral (IV/IM) and alternative (rectal, spinal/epidural, transdermal) routes are well-established in clinical practice to ensure therapeutic plasma concentrations. **High-Yield Clinical Pearls for NEET-PG:** * **Metabolism:** Morphine is conjugated in the liver to **Morphine-6-glucuronide** (active metabolite, potent analgesic) and **Morphine-3-glucuronide** (neurotoxic, causes seizures). * **Contraindication:** Avoid in **head injuries** (increases intracranial pressure due to CO2 retention and vasodilation) and **bronchial asthma**. * **Specific Use:** It is the drug of choice for **Acute Left Ventricular Failure** (cardiac asthma) due to its venodilatory effect (reducing preload) and relief of air hunger. * **Mnemonic for Morphine Side Effects:** **MORPHINE** (Miosis, Out of it/Sedation, Respiratory depression, Pneumonia/Aspiration, Hypotension, Infrequency/Constipation, Nausea, Emesis).

Question 76: Which of the following is the least acidic NSAID?

A. Aspirin
B. Etodolac
C. Diclofenac
D. Nabumetone (Correct Answer)

Explanation: The correct answer is **Nabumetone**. **Why Nabumetone is the correct answer:** Most Non-Steroidal Anti-inflammatory Drugs (NSAIDs) are weak organic acids (carboxylic acid derivatives). However, **Nabumetone** is a unique **non-acidic prodrug** (a naphthylalkanone). Because it lacks a free carboxylic acid group, it is the least acidic among the options. After absorption, it undergoes hepatic metabolism to form its active metabolite, 6-methoxy-2-naphthylacetic acid (6-MNA), which then inhibits COX enzymes. Its non-acidic nature and prodrug status result in a lower incidence of direct gastric mucosal irritation compared to acidic NSAIDs. **Why the other options are incorrect:** * **Aspirin (Acetylsalicylic acid):** A potent organic acid that directly irritates the gastric mucosa and irreversibly inhibits COX-1 and COX-2. * **Diclofenac:** A phenylacetic acid derivative. It is highly acidic and carries a significant risk of GI side effects if not used with caution. * **Etodolac:** An acetic acid derivative. While it is relatively COX-2 selective, it remains an acidic compound [1]. **High-Yield NEET-PG Pearls:** * **Prodrug NSAIDs:** Nabumetone and Sulindac are the classic examples. * **Gastric Safety:** Because Nabumetone is non-acidic and does not inhibit gastric prostaglandins until it is converted in the liver, it is often preferred in patients with a history of GI sensitivity. * **Long Half-life:** Nabumetone has a long half-life (approx. 24 hours), allowing for once-daily dosing. * **Excretion:** Most NSAIDs are highly protein-bound and excreted via the kidneys; however, Nabumetone’s active metabolite is primarily excreted in urine.

Question 77: What is the chief advantage of ketorolac over aspirin?

A. Ketorolac can be combined more safely with an opioid such as codeine.
B. Ketorolac does not prolong bleeding time.
C. Ketorolac is available in a parenteral formulation that can be used intramuscularly or intravenously. (Correct Answer)
D. Ketorolac is less likely to cause acute renal failure in patients with pre-existing renal impairment.

Explanation: **Explanation:** Ketorolac is a potent Non-Steroidal Anti-Inflammatory Drug (NSAID) primarily used for its high analgesic efficacy, which is comparable to low-dose morphine in managing moderate-to-severe postoperative pain. **Why Option C is correct:** The chief clinical advantage of ketorolac over aspirin and many other traditional NSAIDs is its availability in **parenteral formulations (IM/IV)**. While aspirin is primarily administered orally, ketorolac’s injectable form allows for rapid onset and its use in patients who are "nil per oral" (NPO) or experiencing nausea/vomiting post-surgery. This makes it a unique "opioid-sparing" parenteral analgesic. **Why other options are incorrect:** * **Option A:** Both aspirin and ketorolac can be combined with opioids; ketorolac does not have a specific "safety" advantage in this combination. * **Option B:** Like aspirin, ketorolac inhibits cyclooxygenase (COX) and prevents thromboxane A2 synthesis, thereby **prolonging bleeding time**. In fact, ketorolac carries a significant risk of postoperative bleeding. * **Option D:** Ketorolac is highly nephrotoxic. It inhibits renal prostaglandins, which can lead to acute renal failure, especially in dehydrated patients or those with pre-existing renal impairment. It is contraindicated in patients with advanced renal failure. **High-Yield Clinical Pearls for NEET-PG:** * **Duration Limit:** Ketorolac therapy (parenteral or oral) should **not exceed 5 days** due to the high risk of GI ulceration and renal damage. * **Potency:** It is often described as having "aspirin-like" anti-inflammatory action but "morphine-like" analgesic potency. * **Topical Use:** It is also used as 0.5% ophthalmic drops for seasonal allergic conjunctivitis and post-cataract surgery inflammation.

Question 78: Mechanism of analgesia is by:

A. Nociceptin stimulation
B. Nocistatin stimulation (Correct Answer)
C. O.L.R.I
D. All

Explanation: ### Explanation The correct answer is **B. Nocistatin stimulation**. **Understanding the Concept:** Nocistatin and Nociceptin (also known as Orphanin FQ) are both derived from the same precursor molecule, **Pre-pronociceptin**. However, they exert diametrically opposite effects on pain perception: 1. **Nocistatin (The Analgesic):** Nocistatin is a neuropeptide that **inhibits** pain transmission. It acts as a potent **analgesic** by blocking the pro-nociceptive effects of nociceptin and reducing the release of excitatory neurotransmitters (like glutamate) in the spinal cord. 2. **Nociceptin (The Pro-nociceptive):** Conversely, Nociceptin (Option A) primarily acts on the **ORL-1 (Opioid Receptor-Like 1)** receptor. While its role is complex, in the spinal cord, it generally acts as a **pro-nociceptive** (hyperalgesic) agent, meaning it increases the sensitivity to pain. **Analysis of Options:** * **Option A (Nociceptin stimulation):** Incorrect. Stimulation of nociceptin receptors typically results in hyperalgesia (increased pain) rather than analgesia. * **Option C (O.L.R.I):** Incorrect. This refers to the **Opioid Receptor-Like 1** (now termed NOP receptor). Stimulation of this receptor by its natural ligand (nociceptin) is generally associated with the induction of pain at the spinal level. * **Option D (All):** Incorrect, as only Nocistatin provides a clear analgesic effect. **High-Yield Clinical Pearls for NEET-PG:** * **Precursor:** Both Nociceptin and Nocistatin are encoded by the **PNOC gene**. * **Receptor:** Nociceptin binds to the **NOP receptor** (formerly ORL-1), which is a G-protein coupled receptor but does *not* bind classical opioids like morphine or naloxone. * **Nocistatin's Mechanism:** It specifically antagonizes nociceptin-induced allodynia and hyperalgesia, making it a target for future non-opioid analgesic development.

Question 79: NSAIDs cause gastric ulceration because they:

A. inhibit COX-2 enzyme
B. inhibit mucus production (Correct Answer)
C. increase HCl production
D. delay gastric emptying

Explanation: **Explanation:** The primary mechanism behind NSAID-induced gastric ulceration is the **inhibition of Prostaglandin (PG) synthesis**, specifically PGE2 and PGI2. Under normal physiological conditions, these prostaglandins are synthesized by the **COX-1 enzyme** and serve a cytoprotective role in the gastric mucosa by: 1. **Stimulating mucus and bicarbonate secretion**, which forms the physical "gastric mucosal barrier." 2. Maintaining mucosal blood flow. 3. Reducing gastric acid secretion. By inhibiting COX-1, NSAIDs lead to a significant **decrease in mucus production**, leaving the gastric epithelium vulnerable to damage from luminal acid and pepsin, eventually resulting in erosions and ulcers. **Analysis of Incorrect Options:** * **A. Inhibit COX-2 enzyme:** COX-2 is primarily induced during inflammation. While COX-2 inhibitors (e.g., Celecoxib) are "gastric-sparing," the gastric toxicity of traditional NSAIDs is specifically due to the inhibition of the constitutive **COX-1** isoform. * **C. Increase HCl production:** While prostaglandins normally inhibit acid secretion, the *dominant* factor in ulcer formation by NSAIDs is the loss of protective mucus and bicarbonate, not a primary massive increase in HCl production. * **D. Delay gastric emptying:** NSAIDs do not significantly affect gastric motility or emptying times in a way that contributes to ulcerogenesis. **High-Yield Clinical Pearls for NEET-PG:** * **Misoprostol:** A PGE1 analogue used specifically to prevent NSAID-induced ulcers. * **Topical vs. Systemic:** NSAIDs cause damage both locally (topical irritation) and systemically (via COX inhibition after absorption). * **Risk Factors:** Elderly patients, history of peptic ulcer disease, and concomitant use of corticosteroids or anticoagulants increase the risk of NSAID-induced GI bleeds.

Question 80: Which of the following disease-modifying anti-rheumatoid drugs is a prodrug?

A. Etanercept
B. Nimesulide
C. Sulfasalazine (Correct Answer)
D. Colchicine

Explanation: **Explanation:** **Sulfasalazine** is a classic example of a **prodrug** used in the management of Rheumatoid Arthritis (RA) and Inflammatory Bowel Disease (IBD). It consists of two moieties—**Sulfapyridine** and **5-Aminosalicylic acid (5-ASA)**—linked by a covalent **azo bond**. Upon reaching the colon, bacterial enzymes (azoreductases) cleave this bond. While 5-ASA acts locally in IBD, the sulfapyridine moiety is absorbed systemically and is responsible for the disease-modifying effect in Rheumatoid Arthritis. **Analysis of Incorrect Options:** * **A. Etanercept:** This is a biological DMARD. It is a genetically engineered soluble **TNF-receptor fusion protein** that binds to TNF-α. It is active in its administered form and is not a prodrug. * **B. Nimesulide:** A selective **COX-2 inhibitor** (NSAID). It is an active drug used for acute pain and is not classified as a DMARD. * **C. Colchicine:** An alkaloid used primarily for **acute gout** and Familial Mediterranean Fever. It works by binding to tubulin and inhibiting microtubule polymerization. It is an active compound, not a prodrug. **High-Yield Clinical Pearls for NEET-PG:** * **Leflunomide** is another high-yield DMARD that is a **prodrug** (converted to its active metabolite **A77 1726**), which inhibits the enzyme **dihydroorotate dehydrogenase**, halting pyrimidine synthesis. * Sulfasalazine is considered safe during pregnancy (Category B), making it a preferred DMARD for pregnant patients with RA. * A common side effect of Sulfasalazine to remember for exams is **reversible oligospermia** and yellow-orange discoloration of urine/skin.

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

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Migraine Therapeutics

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Neuropathic Pain Management

Practice Questions

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