Analgesics and Anti-inflammatory Drugs — MCQs

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

Question 31: Methotrexate is used in all the following conditions except?

A. Sickle cell anemia (Correct Answer)
B. Psoriasis
C. Rheumatoid arthritis
D. Ankylosing spondylitis

Explanation: ### Explanation **1. Why Sickle Cell Anemia is the Correct Answer:** Methotrexate (MTX) is a folate antagonist that inhibits **dihydrofolate reductase (DHFR)**, leading to a decrease in DNA synthesis. It is primarily used as a Disease-Modifying Anti-Rheumatic Drug (DMARD) and a chemotherapeutic agent. It has **no role** in the management of Sickle Cell Anemia. The drug of choice for reducing the frequency of vaso-occlusive crises in Sickle Cell Anemia is **Hydroxyurea**, which works by increasing the levels of Fetal Hemoglobin (HbF). **2. Why the other options are incorrect:** * **Psoriasis:** MTX is a standard systemic treatment for severe, recalcitrant psoriasis. It works by inhibiting the rapid proliferation of epidermal cells (keratinocytes) and providing systemic anti-inflammatory effects. * **Rheumatoid Arthritis (RA):** MTX is the **"Anchor Drug"** and the first-line DMARD for RA. It reduces joint destruction and slows disease progression by inhibiting cytokine production and increasing extracellular adenosine. * **Ankylosing Spondylitis:** While TNF-inhibitors are preferred for axial disease, MTX is frequently used as a DMARD to manage peripheral joint involvement in patients with Ankylosing Spondylitis. **3. High-Yield Clinical Pearls for NEET-PG:** * **Mechanism of Action:** Competitive inhibition of DHFR; at low doses (for RA), it also increases **Adenosine**, which acts as a potent anti-inflammatory mediator. * **Toxicity:** The most common side effect is mucosal ulceration (stomatitis). The most serious are **hepatotoxicity** (cirrhosis) and **pulmonary fibrosis**. * **Rescue Therapy:** **Leucovorin (Folinic acid)** is used to "rescue" normal cells from MTX toxicity by bypassing the inhibited DHFR enzyme. * **Contraindication:** It is highly **teratogenic** (causes neural tube defects) and must be stopped at least 3 months before conception in both men and women.

Question 32: All are effects of morphine EXCEPT:

A. Miosis
B. Delayed gastric emptying
C. Respiratory depression
D. Hyperalgesia (Correct Answer)

Explanation: **Explanation:** Morphine is the prototype opioid agonist acting primarily on **$\mu$-opioid receptors**. The correct answer is **Hyperalgesia** because morphine is an **analgesic** (relieves pain); it does not typically cause increased sensitivity to pain (hyperalgesia) as a primary pharmacological effect. While "Opioid-Induced Hyperalgesia" (OIH) can occur with chronic high-dose use or rapid titration, it is considered a paradoxical side effect rather than a standard physiological effect of the drug. **Analysis of Options:** * **Miosis (A):** Morphine stimulates the **Edinger-Westphal nucleus** of the 3rd cranial nerve, leading to "pin-point pupils." This is a diagnostic sign of opioid overdose as tolerance does not develop to this effect. * **Delayed gastric emptying (B):** Opioids increase smooth muscle tone but decrease propulsive rhythmic contractions in the GI tract. This leads to delayed gastric emptying and constipation (via $\mu$-receptors in the myenteric plexus). * **Respiratory depression (C):** This is the most dangerous side effect. Morphine reduces the sensitivity of the brainstem respiratory centers to carbon dioxide ($CO_2$). **High-Yield Clinical Pearls for NEET-PG:** 1. **Mnemonic for Morphine Effects:** **"MORPHINE"** – **M**iosis, **O**ut of it (sedation), **R**espiratory depression, **P**neumonia (aspiration), **H**ypotension, **I**nfrequent stools (constipation), **N**ausea, **E**mesis. 2. **Tolerance:** Tolerance develops to most effects **EXCEPT** Miosis and Constipation. 3. **Contraindication:** Morphine is contraindicated in **Head Injury** because it causes $CO_2$ retention, leading to cerebral vasodilation and increased intracranial pressure. 4. **Biliary Colic:** Morphine can aggravate biliary colic by causing spasm of the **Sphincter of Oddi**.

Question 33: Which drug is highly vestibulotoxic?

A. Cisplatin
B. Streptomycin (Correct Answer)
C. Dihydrostreptomycin
D. Quinine

Explanation: **Explanation:** Ototoxicity is a classic side effect of several drug classes, manifesting as either **vestibulotoxicity** (vertigo, ataxia, loss of balance) or **cochleotoxicity** (tinnitus, hearing loss). **1. Why Streptomycin is correct:** Among aminoglycosides, **Streptomycin** and Gentamicin are predominantly **vestibulotoxic**. They selectively damage the sensory hair cells of the vestibular apparatus. Streptomycin is so specifically toxic to the vestibular system that it was historically used therapeutically to ablate vestibular function in patients with severe Meniere’s disease. **2. Analysis of Incorrect Options:** * **Cisplatin (Option A):** This platinum-based chemotherapeutic agent is highly **cochleotoxic**, causing permanent, high-frequency hearing loss. It is not primarily vestibulotoxic. * **Dihydrostreptomycin (Option C):** Unlike its parent drug Streptomycin, this derivative is notoriously **cochleotoxic**. It was largely discontinued because it causes severe and unpredictable hearing loss. * **Quinine (Option D):** Quinine (and Salicylates) causes "Cinchonism," which includes tinnitus and temporary hearing loss. This is usually reversible and less severe than aminoglycoside-induced damage. **3. NEET-PG High-Yield Pearls:** * **Aminoglycoside Rule of Thumb:** * **Vestibulotoxic:** Streptomycin, Gentamicin. * **Cochleotoxic:** Kanamycin, Amikacin, Neomycin, Dihydrostreptomycin. * **Both:** Tobramycin. * **Mechanism:** Aminoglycosides generate reactive oxygen species (ROS) in the inner ear and have a long half-life in the perilymph (30-50 hours), leading to progressive accumulation. * **Loop Diuretics:** Ethacrynic acid and Furosemide can cause ototoxicity, which is often synergistic when combined with aminoglycosides.

Question 34: Allopurinol works by which mechanism?

A. Decreased excretion of uric acid
B. Decreased metabolism of uric acid
C. Increased excretion of uric acid
D. Decreased synthesis of uric acid (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. Decreased synthesis of uric acid** **Mechanism of Action:** Allopurinol is a **hypoxanthine analog** that acts as a potent competitive inhibitor of the enzyme **Xanthine Oxidase (XO)**. In the body, purines are metabolized into hypoxanthine, then to xanthine, and finally to uric acid via the action of Xanthine Oxidase. By inhibiting this enzyme, Allopurinol prevents the final steps of purine catabolism, thereby **decreasing the synthesis of uric acid**. Its primary metabolite, **Alloxanthine (Oxypurinol)**, is a non-competitive inhibitor of the same enzyme and has a much longer half-life, contributing significantly to the drug's therapeutic effect. **Analysis of Incorrect Options:** * **A & C (Excretion):** Allopurinol does not directly affect the renal handling or excretion of uric acid. Drugs that increase excretion are called **Uricosurics** (e.g., Probenecid, Sulfinpyrazone, Lesinurad). * **B (Metabolism):** Uric acid is the end product of purine metabolism in humans. Allopurinol inhibits its *production* rather than increasing its breakdown. (Note: Recombinant urate oxidase enzymes like **Rasburicase** or **Pegloticase** work by metabolizing uric acid into the more soluble allantoin). **Clinical Pearls for NEET-PG:** * **Drug of Choice:** Allopurinol is the first-line agent for **Chronic Gout** (intercritical period) and for preventing **Tumor Lysis Syndrome**. * **Acute Gout Warning:** Never start Allopurinol during an acute attack of gout, as a sudden drop in serum urate levels can mobilize crystals from tissues and worsen/prolong the inflammation. * **Drug Interaction:** It significantly increases the toxicity of **6-Mercaptopurine (6-MP)** and **Azathioprine** because these drugs are metabolized by Xanthine Oxidase. Reduce their dose by 75% if co-administered. * **Hypersensitivity:** Watch for **HLA-B*5801** positive patients, as they are at high risk for Stevens-Johnson Syndrome (SJS) when taking Allopurinol.

Question 35: For pain control in a patient with a history of GI bleeding, which of the following analgesics is generally preferred?

A. Nimesulide
B. Ibuprofen
C. Rofecoxib (Correct Answer)
D. Pentazocine

Explanation: **Explanation:** The core concept in this question is the differential inhibition of Cyclooxygenase (COX) enzymes. Traditional NSAIDs inhibit both COX-1 and COX-2. COX-1 is constitutively expressed in the gastric mucosa, where it produces cytoprotective prostaglandins ($PGE_2$ and $PGI_2$) that maintain the mucosal barrier. **Why Rofecoxib is correct:** **Rofecoxib** is a highly selective **COX-2 inhibitor** (Coxib). By selectively inhibiting COX-2 (responsible for inflammation and pain) while sparing COX-1 (responsible for gastric protection), it significantly reduces the risk of gastric ulcers and GI bleeding compared to non-selective NSAIDs. Therefore, it is preferred in patients with a high risk of GI complications. **Analysis of Incorrect Options:** * **Ibuprofen:** A non-selective NSAID that inhibits both COX-1 and COX-2. It is a leading cause of drug-induced gastric erosions and is contraindicated in patients with active or past GI bleeds. * **Nimesulide:** A "preferential" COX-2 inhibitor, but it still retains significant COX-1 inhibitory activity and carries a risk of hepatotoxicity. It is not as GI-sparing as the "selective" Coxibs. * **Pentazocine:** An opioid agonist-antagonist. While it doesn't cause GI bleeding, it is not the first-line choice for routine inflammatory pain control due to its side effect profile (hallucinations, dysphoria, and increased cardiac workload). **High-Yield Clinical Pearls for NEET-PG:** * **The "Coxib" Paradox:** While selective COX-2 inhibitors are safer for the GI tract, they carry an increased risk of **thrombotic cardiovascular events** (MI/Stroke) because they inhibit $PGI_2$ (vasodilator/anti-aggregatory) in endothelium without affecting $TXA_2$ (vasoconstrictor/pro-aggregatory) in platelets. * **Rofecoxib** was famously withdrawn globally due to this increased cardiovascular risk (VIGOR study). * **Drug of choice** for pain in a patient with a history of peptic ulcer/GI bleed is **Paracetamol (Acetaminophen)**, as it has negligible peripheral COX inhibition. If an anti-inflammatory is mandatory, a selective COX-2 inhibitor or a non-selective NSAID combined with a **Proton Pump Inhibitor (PPI)** is used.

Question 36: Which of the following is NOT a contraindication in the therapy with opioids?

A. Use in a head injury patient
B. Use in impaired pulmonary function
C. Use of an agonist with a mixed agonist-antagonist
D. Use in severe constant pain (Correct Answer)

Explanation: **Explanation:** **1. Why "Use in severe constant pain" is the correct answer:** Severe constant pain is the **primary clinical indication** for opioid therapy, not a contraindication. Opioids (like Morphine and Fentanyl) are the gold standard for managing moderate-to-severe acute pain (e.g., myocardial infarction, post-operative pain) and chronic cancer pain. They act on $\mu$-receptors in the CNS to raise the pain threshold and alter the emotional perception of pain. **2. Why the other options are Contraindications:** * **Head Injury:** Opioids cause respiratory depression, leading to CO₂ retention. CO₂ is a potent cerebral vasodilator which increases cerebral blood flow and **increases intracranial pressure (ICP)**. This can mask neurological signs (like pupillary changes) and worsen the clinical condition. * **Impaired Pulmonary Function:** Opioids decrease the sensitivity of the brainstem respiratory center to CO₂. In patients with COPD, asthma, or respiratory failure, this can precipitate fatal respiratory depression. * **Agonist with Mixed Agonist-Antagonist:** Administering a mixed agent (e.g., Pentazocine or Nalbuphine) to a patient already on a pure $\mu$-agonist (e.g., Morphine) can antagonize the analgesic effects and **precipitate withdrawal symptoms** in opioid-dependent individuals. **NEET-PG High-Yield Pearls:** * **Biliary Colic:** Opioids (except Pethidine) can cause contraction of the Sphincter of Oddi, potentially worsening biliary pain. * **Pin-point pupil (Miosis):** A classic sign of opioid overdose; it occurs due to stimulation of the Edinger-Westphal nucleus. * **Tolerance:** Develops to most effects except **miosis and constipation**. * **Antidote:** Naloxone is the drug of choice for acute opioid poisoning.

Question 37: Which drug can exacerbate asthma secondary to irreversible nonselective inhibition of the cyclooxygenase pathway?

A. Aspirin (Correct Answer)
B. Ibuprofen
C. Ketorolac
D. Celecoxib

Explanation: ### Explanation **Correct Option: A (Aspirin)** The question highlights two specific pharmacological characteristics: **irreversible inhibition** and **nonselective COX inhibition**. Aspirin (Acetylsalicylic acid) is the only NSAID that covalently modifies cyclooxygenase (COX-1 and COX-2) by acetylating a serine residue in the active site, leading to irreversible inhibition. **Mechanism of Asthma Exacerbation:** When the COX pathway is blocked, arachidonic acid is shunted toward the **Lipoxygenase (LOX) pathway**. This leads to an overproduction of **cysteinyl leukotrienes** (LTC4, LTD4, LTE4), which are potent bronchoconstrictors. This clinical phenomenon is known as **Aspirin-Exacerbated Respiratory Disease (AERD)** or Samter’s Triad (Asthma, Nasal polyps, and Aspirin sensitivity). **Why other options are incorrect:** * **B & C (Ibuprofen and Ketorolac):** While these are nonselective COX inhibitors that can trigger asthma via the same leukotriene shunt, their binding to the COX enzyme is **reversible** (competitive inhibition). * **D (Celecoxib):** This is a **selective COX-2 inhibitor**. It does not significantly inhibit COX-1 in the respiratory tract and is generally considered safer for patients with aspirin-sensitive asthma. **High-Yield Clinical Pearls for NEET-PG:** * **Samter’s Triad:** Asthma + Aspirin sensitivity + Nasal polyposis. * **Anti-platelet effect:** Aspirin’s effect lasts for the lifetime of a platelet (7–10 days) because platelets are anucleated and cannot synthesize new COX enzymes. * **Drug of Choice:** For patients with AERD who require an analgesic, **Acetaminophen** (in low doses) or **Selective COX-2 inhibitors** are preferred. * **Treatment of AERD:** Leukotriene receptor antagonists (e.g., **Montelukast, Zafirlukast**) are particularly effective in managing these patients.

Question 38: Abatacept is a:

A. IL1 antagonist
B. IFN-a neutralizing drug
C. Immunosuppressant
D. Fusion protein (Correct Answer)

Explanation: **Explanation:** **Abatacept** is a recombinant **fusion protein** used primarily in the treatment of Rheumatoid Arthritis. It consists of the extracellular domain of human **CTLA-4** (Cytotoxic T-lymphocyte-associated antigen 4) fused to the **Fc portion of human IgG1**. **Mechanism of Action:** Its primary role is to act as a **selective co-stimulation modulator**. For a T-cell to become activated, it requires two signals: 1. The binding of the T-cell receptor to the Antigen-MHC complex. 2. A co-stimulatory signal (binding of **CD80/CD86** on the antigen-presenting cell to **CD28** on the T-cell). Abatacept binds to CD80 and CD86 with high affinity, preventing them from binding to CD28. This inhibits T-cell activation and the subsequent inflammatory cascade. **Analysis of Incorrect Options:** * **A. IL-1 antagonist:** This describes **Anakinra**, which is a recombinant form of the human interleukin-1 receptor antagonist. * **B. IFN-α neutralizing drug:** This refers to drugs like **Sifalimumab** or **Anifrolumab** (IFN receptor blocker), used in Systemic Lupus Erythematosus (SLE). * **C. Immunosuppressant:** While Abatacept has immunosuppressive effects, "Fusion protein" is the more specific pharmacological classification required for NEET-PG. In pharmacology questions, structural/class-specific definitions take precedence over broad functional descriptions. **High-Yield Clinical Pearls for NEET-PG:** * **Belatacept:** A related fusion protein (modified Abatacept) used specifically in renal transplantation to prevent graft rejection. * **Suffix Clue:** Drugs ending in **"-cept"** (e.g., Etanercept, Abatacept, Aflibercept) are typically **fusion proteins** involving a receptor linked to an Fc fragment. * **Contraindication:** Do not use Abatacept concurrently with TNF-inhibitors (e.g., Infliximab) due to an increased risk of serious infections.

Question 39: Which of the following drugs does NOT inhibit platelet aggregation?

A. Aspirin
B. Celecoxib (Correct Answer)
C. Ibuprofen
D. Clopidogrel

Explanation: **Explanation:** The correct answer is **Celecoxib**. The underlying medical concept involves the differential expression of Cyclooxygenase (COX) enzymes in platelets versus vascular endothelium. 1. **Why Celecoxib is correct:** Celecoxib is a **selective COX-2 inhibitor**. Platelets only express **COX-1**, which is responsible for synthesizing **Thromboxane A2 (TXA2)**—a potent platelet aggregator and vasoconstrictor. Because Celecoxib does not inhibit COX-1 at therapeutic doses, it does not affect TXA2 production or platelet aggregation. In fact, by inhibiting COX-2 in the endothelium (which produces PGI2, an anti-aggregatory prostaglandin), selective COX-2 inhibitors can shift the balance toward a pro-thrombotic state, increasing cardiovascular risk. 2. **Why other options are incorrect:** * **Aspirin:** Irreversibly inhibits COX-1, leading to a lifelong (for the platelet) suppression of TXA2. It is the gold standard antiplatelet NSAID. * **Ibuprofen:** A non-selective COX inhibitor that reversibly inhibits COX-1, thereby temporarily inhibiting platelet aggregation. * **Clopidogrel:** A P2Y12 receptor antagonist that inhibits ADP-induced platelet aggregation. It is a potent antiplatelet agent used in ACS and post-stenting. **High-Yield Clinical Pearls for NEET-PG:** * **The "Aspirin-Ibuprofen Interaction":** If taken together, Ibuprofen can block Aspirin’s access to the COX-1 active site, reducing its cardioprotective effect. Always advise taking Aspirin at least 30 minutes before or 8 hours after Ibuprofen. * **COX-2 Selectivity & Sulfa Allergy:** Celecoxib contains a sulfonamide moiety; use caution in patients with sulfa allergies. * **Platelet Lifespan:** Because Aspirin is an irreversible inhibitor, its effects last for the life of the platelet (**7–10 days**).

Question 40: Which effect of morphine shows the least tolerance?

A. Analgesia
B. Respiratory depression
C. Constipation (Correct Answer)
D. Bradycardia

Explanation: **Explanation:** Tolerance is a pharmacological phenomenon where repeated administration of a drug results in a diminished effect, requiring higher doses to achieve the same therapeutic response. In the case of Morphine (an opioid agonist), tolerance develops at different rates for different physiological effects. **Why Constipation is correct:** Tolerance develops to most effects of morphine, but it is **minimal or absent** for two specific effects: **Constipation** and **Miosis** (pin-point pupils). Morphine acts on $\mu$-opioid receptors in the gastrointestinal tract to decrease motility and secretions. Because tolerance does not develop to this effect, chronic opioid users (such as those in palliative care or with addiction) suffer from persistent, long-term constipation, often requiring stimulant laxatives. **Analysis of Incorrect Options:** * **Analgesia:** High tolerance develops. Patients on chronic morphine therapy for pain often require dose escalation over time to maintain the same level of pain relief. * **Respiratory Depression:** High tolerance develops. This is clinically significant because it allows chronic users to tolerate doses that would be fatal to an opioid-naive individual. * **Bradycardia:** Moderate tolerance develops to the cardiovascular effects of opioids. **NEET-PG High-Yield Pearls:** * **Mnemonic for "No Tolerance":** Remember **"M-C"** (Miosis and Constipation). * **Miosis:** This is a diagnostic sign of opioid overdose; because no tolerance develops, it remains present even in chronic addicts. * **Mechanism of Constipation:** Primarily mediated by $\mu_2$ receptors in the myenteric plexus, leading to increased segmenting contractions but decreased propulsive (peristaltic) activity. * **Treatment:** Methylnaltrexone (a peripheral $\mu$-antagonist) can be used to treat opioid-induced constipation without reversing central analgesia.

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

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