Analgesics and Anti-inflammatory Drugs — MCQs

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

Question 241: Buprenorphine is?

A. Partial agonist at mu receptor (Correct Answer)
B. Partial agonist at kappa receptor
C. Full agonist at n receptor
D. Full agonist at kappa receptor

Explanation: **Explanation:** Buprenorphine is a semi-synthetic highly lipophilic opioid. Its pharmacological profile is unique and frequently tested in NEET-PG due to its specific receptor interactions: 1. **Why Option A is Correct:** Buprenorphine acts as a **partial agonist at $\mu$ (mu) receptors**. It has a very high affinity for these receptors but low intrinsic activity. This results in a "ceiling effect" for respiratory depression and euphoria, making it safer than full agonists like morphine. It also dissociates very slowly from the $\mu$ receptor, leading to a long duration of action. 2. **Why Options B and D are Incorrect:** Buprenorphine is actually an **antagonist at $\kappa$ (kappa) receptors**, not an agonist. This kappa-antagonism is clinically significant as it may contribute to its antidepressant effects and lack of psychotomimetic side effects (like dysphoria) often associated with kappa-agonists. 3. **Why Option C is Incorrect:** There is no "n receptor" in standard opioid pharmacology; the three primary receptors are $\mu$, $\kappa$, and $\delta$. Buprenorphine acts as an agonist at the **ORL-1 (nociceptin)** receptor, but its primary clinical classification remains a $\mu$-partial agonist. **High-Yield Clinical Pearls for NEET-PG:** * **Ceiling Effect:** Increasing the dose beyond a point does not increase analgesia or respiratory depression. * **Opioid Withdrawal:** Because it has a higher affinity than morphine, it can displace full agonists from receptors, potentially **precipitating withdrawal** in opioid-dependent individuals. * **Clinical Uses:** Used in opioid detoxification (substitution therapy) and management of chronic pain. * **Naloxone Resistance:** Due to its slow dissociation from receptors, buprenorphine-induced respiratory depression is difficult to reverse with standard doses of Naloxone.

Question 242: What is the effective and safe drug for intractable pain in the terminal cancer stage?

A. Injectable pethidine
B. Injectable ketamine
C. Oral Brufen
D. Oral Morphine (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. Oral Morphine** The management of cancer pain follows the **WHO Analgesic Ladder**. For severe, intractable pain (Step 3), strong opioids are the mainstay of treatment. **Oral Morphine** is considered the "gold standard" for terminal cancer pain because it is highly effective, has a well-established safety profile for long-term use, and allows for consistent plasma levels when administered on a fixed schedule. The oral route is preferred in palliative care as it preserves patient autonomy, is non-invasive, and avoids the "peak and valley" effect associated with intermittent injections. **Analysis of Incorrect Options:** * **Injectable Pethidine (A):** Pethidine is contraindicated for chronic pain. Its metabolite, **norpethidine**, has a long half-life and is neurotoxic, leading to tremors, myoclonus, and seizures with repeated dosing. It also has a shorter duration of action than morphine. * **Injectable Ketamine (B):** While ketamine is an NMDA antagonist used for refractory neuropathic pain, it is not a first-line agent for terminal cancer pain. Its side effect profile (hallucinations, emergence delirium) and the requirement for parenteral administration make it less ideal than oral opioids. * **Oral Brufen (Ibuprofen) (C):** As an NSAID (Step 1 drug), it is insufficient for "intractable" or severe pain on its own, though it may be used as an adjuvant for bone metastasis. **Clinical Pearls for NEET-PG:** * **WHO Ladder Step 3:** Strong opioids (Morphine, Fentanyl, Oxycodone). * **Miosis & Constipation:** These are two side effects of morphine to which tolerance **never** develops. Patients on morphine should almost always be prescribed a stimulant laxative. * **First-pass metabolism:** Oral morphine undergoes significant first-pass metabolism; hence, the oral dose is usually 3 times the parenteral dose (3:1 ratio). * **Drug of choice for Dyspnea:** Low-dose morphine is also the drug of choice for palliating terminal dyspnea (air hunger).

Question 243: Which of the following is least narcotic?

A. Morphine
B. Codeine
C. Thebaine
D. Papaverine (Correct Answer)

Explanation: **Explanation:** The classification of opium alkaloids is based on their chemical structure and pharmacological action. Opium contains two distinct chemical classes: **Phenanthrene derivatives** and **Benzylisoquinoline derivatives**. 1. **The Correct Answer (D): Papaverine** Papaverine belongs to the **Benzylisoquinoline** group. Unlike phenanthrenes, these compounds have **no analgesic or narcotic properties**. Instead, Papaverine acts as a direct-acting smooth muscle relaxant (vasodilator) by inhibiting phosphodiesterase enzymes. Therefore, it is the "least narcotic" (non-narcotic) among the options. 2. **Analysis of Incorrect Options:** * **A. Morphine:** The prototype phenanthrene alkaloid. It is a potent $\mu$-opioid receptor agonist and the gold standard for narcotic analgesics. * **B. Codeine:** A phenanthrene derivative (methyl-morphine). While less potent than morphine, it possesses significant narcotic, analgesic, and antitussive properties. * **C. Thebaine:** Although not used clinically due to its tendency to cause convulsions rather than depression, it is chemically a phenanthrene alkaloid and serves as a precursor for semi-synthetic opioids like oxycodone and naloxone. **High-Yield Clinical Pearls for NEET-PG:** * **Opium Composition:** Contains ~10% Morphine, 0.5% Codeine, and 1% Papaverine. * **Papaverine Clinical Use:** Historically used for erectile dysfunction (intracavernosal injection) and to relieve visceral spasms or peripheral vascular spasms. * **Noscapine:** Another Benzylisoquinoline alkaloid found in opium; like Papaverine, it is **non-narcotic** and used primarily as an antitussive. * **Mnemonic:** Phenanthrenes (**P**ainkillers) vs. Benzylisoquinolines (**B**lood vessel/Bronchi relaxants).

Question 244: Aspirin should be used with caution in the following groups of patients because of which of the following reasons?

A. In diabetics because it can cause hyperglycemia
B. In children with viral disease, because of the risk of Reye's syndrome
C. In gout, because it can increase serum uric acid (Correct Answer)
D. In pregnancy, because of high risk of teratogenicity

Explanation: **Explanation:** **1. Why Option C is Correct:** Aspirin exhibits a **dose-dependent effect** on uric acid excretion. At low doses (typically <2g/day), aspirin inhibits the active secretion of uric acid in the proximal renal tubules. This leads to **hyperuricemia**, which can precipitate or worsen an acute attack of gout. While high-dose aspirin (>5g/day) is uricosuric (increases excretion), such high doses are clinically toxic and rarely used, making aspirin generally contraindicated in gouty patients. **2. Why Other Options are Incorrect:** * **Option A:** Aspirin does not cause hyperglycemia. In fact, in very high doses, salicylates can cause **hypoglycemia** by increasing peripheral glucose utilization and stimulating insulin secretion. * **Option B:** While the risk of **Reye’s syndrome** is a real concern in children with viral infections (like Varicella or Influenza), the question asks for the *reasoning* behind the provided correct answer (Gout). Option B is a valid contraindication, but Option C is the specific focus of this clinical scenario regarding metabolic excretion. * **Option D:** Aspirin is not primarily known for high teratogenicity (like Thalidomide or Phenytoin). However, it is avoided in the third trimester because it can cause **premature closure of the Ductus Arteriosus** and increase the risk of postpartum hemorrhage. **High-Yield Clinical Pearls for NEET-PG:** * **Analgesic Nephropathy:** Chronic use of aspirin with other NSAIDs can lead to papillary necrosis and chronic interstitial nephritis. * **Samter’s Triad:** Aspirin sensitivity, Bronchial Asthma, and Nasal Polyps. * **Zero-Order Kinetics:** Aspirin follows first-order kinetics at low doses but shifts to zero-order (saturation) kinetics at anti-inflammatory/toxic doses. * **Antidote for Salicylate Poisoning:** Urinary alkalinization using Sodium Bicarbonate (increases ionization and excretion).

Question 245: Morphine can be administered by all of the following routes EXCEPT:

A. Intramuscular
B. Transdermal (Correct Answer)
C. Epidural
D. Subarachnoid

Explanation: **Explanation:** **1. Why Transdermal is the Correct Answer (The Exception):** Morphine is a highly **hydrophilic** (polar) drug. For a drug to be administered via a transdermal patch, it must be highly **lipophilic** to penetrate the stratum corneum of the skin effectively. Because of its low lipid solubility, morphine cannot be absorbed across the skin in therapeutic concentrations. In contrast, **Fentanyl** and **Buprenorphine** are highly lipophilic opioids and are the standard choices for transdermal delivery. **2. Analysis of Other Options:** * **Intramuscular (IM):** This is a classic route for acute pain management (e.g., myocardial infarction). Morphine has good systemic absorption from muscle tissue. * **Epidural & Subarachnoid (Spinal):** Morphine is frequently used for regional analgesia (e.g., post-operative or labor pain). Due to its hydrophilic nature, when injected into the CSF, it has a slow onset but a **long duration of action** and can spread cranially, leading to a specific risk of delayed respiratory depression. **3. High-Yield Clinical Pearls for NEET-PG:** * **First-pass metabolism:** Morphine undergoes significant hepatic metabolism (glucuronidation); hence, the oral dose is much higher (3x) than the parenteral dose. * **Active Metabolites:** Morphine-6-glucuronide (potent analgesic) and Morphine-3-glucuronide (neurotoxic/seizures). Both accumulate in **renal failure**. * **Miosis & Constipation:** These are the two side effects of morphine to which **tolerance never develops**. * **Contraindication:** Avoid in head injuries (increases intracranial pressure due to CO2 retention and vasodilation).

Question 246: Which one of the following is an established clinical use of morphine?

A. Management of generalized anxiety disorders
B. Relief of pain associated with biliary colic
C. Pulmonary congestion (Correct Answer)
D. Treatment of cough associated with use of ACE inhibitors

Explanation: **Explanation:** **Correct Option: C (Pulmonary Congestion)** Morphine is a cornerstone in the management of **Acute Left Ventricular Failure (LVF)** and **Acute Pulmonary Edema**. Its efficacy is attributed to several mechanisms: 1. **Venodilation:** It increases peripheral venous capacitance (via histamine release and sympathetic inhibition), which reduces **preload** and shifts blood from the pulmonary to the systemic circulation. 2. **Anxiolysis:** It relieves the intense air hunger and anxiety associated with pulmonary edema, thereby reducing the sympathetic drive and myocardial oxygen demand. 3. **Afterload reduction:** To a lesser extent, it causes arterial dilation, reducing the workload on the failing heart. **Analysis of Incorrect Options:** * **A. Generalized Anxiety Disorders:** While morphine is anxiolytic, it is never used for chronic anxiety due to its high potential for addiction, respiratory depression, and tolerance. Benzodiazepines or SSRIs are the drugs of choice. * **B. Biliary Colic:** Morphine is generally **avoided** in biliary colic because it causes contraction of the **Sphincter of Oddi**, which can increase intrabiliary pressure and worsen the pain. NSAIDs or pethidine (which has less effect on the sphincter) are preferred. * **D. Cough associated with ACE inhibitors:** This cough is mediated by bradykinin and substance P. Morphine is a potent antitussive but is reserved for terminal conditions (e.g., lung cancer). ACE inhibitor-induced cough is managed by switching to ARBs. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice for MI Pain:** Morphine is the preferred analgesic for pain in Myocardial Infarction (except in inferior wall MI where it may worsen bradycardia). * **Specific Antidote:** Naloxone is the competitive antagonist used for morphine overdose. * **The "Miosis" Rule:** Morphine causes "pinpoint pupils" (miosis) via the Edinger-Westphal nucleus; tolerance does *not* develop to this effect or to constipation.

Question 247: Gold salts can be used in which of the following conditions?

A. Ankylosing spondylitis
B. Rheumatoid arthritis (Correct Answer)
C. Osteoarthritis
D. Behcet's syndrome

Explanation: **Explanation:** **Gold salts** (e.g., Sodium aurothiomalate, Auranofin) are classified as **Disease-Modifying Anti-Rheumatic Drugs (DMARDs)**. Their primary mechanism involves the inhibition of macrophage phagocytosis, lysosomal enzyme release, and the suppression of cell-mediated immunity, which helps slow the progression of bone and joint destruction. * **Why Rheumatoid Arthritis (RA) is correct:** Gold salts were historically a mainstay in the treatment of active, progressive RA that did not respond to NSAIDs. Although they have largely been replaced by safer and more effective DMARDs like Methotrexate, they remain a classic pharmacological example of second-line therapy for RA. * **Why other options are incorrect:** * **Ankylosing Spondylitis:** This is a seronegative spondyloarthropathy. While DMARDs like Sulfasalazine may be used for peripheral joint involvement, gold salts are not effective for the axial skeleton inflammation characteristic of this condition. * **Osteoarthritis:** This is a degenerative joint disease, not a primary systemic inflammatory/autoimmune condition. Treatment focuses on analgesics (NSAIDs) and lifestyle modifications; DMARDs have no role here. * **Behcet’s Syndrome:** This is a systemic vasculitis. Management typically involves corticosteroids, Colchicine, or immunosuppressants (Azathioprine, Cyclosporine), but not gold salts. **High-Yield Clinical Pearls for NEET-PG:** * **Route of Administration:** Sodium aurothiomalate is given IM; **Auranofin** is the only **oral** gold preparation (though less effective). * **Adverse Effects:** The most common side effect is **dermatitis** (pruritus/rash). The most serious include **nephrotic syndrome** (membranous glomerulonephritis) and **bone marrow suppression** (aplastic anemia). * **Chrysiasis:** A rare side effect where gold deposits in the skin cause a permanent blue-grey discoloration.

Question 248: All of the following drugs are used in the treatment of chronic gout, except?

A. Allopurinol
B. Benzbromarone
C. Pegloticase
D. Methotrexate (Correct Answer)

Explanation: **Explanation:** The management of gout is divided into two phases: treatment of acute attacks (using NSAIDs, Colchicine, or Steroids) and long-term management of **chronic gout** (Urate Lowering Therapy - ULT). **Why Methotrexate is the correct answer:** **Methotrexate** is a folate antagonist and a Disease-Modifying Antirheumatic Drug (DMARD) primarily used in Rheumatoid Arthritis and Psoriasis. It has **no role** in the management of gout. In fact, cytotoxic drugs like methotrexate can occasionally increase uric acid levels due to rapid cell turnover (tumor lysis). **Analysis of incorrect options:** * **Allopurinol:** The first-line drug for chronic gout. It is a **Xanthine Oxidase inhibitor** that reduces the synthesis of uric acid. * **Benzbromarone:** A potent **Uricosuric agent**. It works by inhibiting the URAT1 transporter in the proximal tubule, increasing the renal excretion of uric acid. It is used in patients who are underexcretors of uric acid. * **Pegloticase:** A recombinant **Urate Oxidase (Uricase) enzyme**. It converts uric acid into allantoin, which is highly soluble and easily excreted. It is reserved for refractory or "orphan" gout. **High-Yield Clinical Pearls for NEET-PG:** 1. **Never start ULT during an acute attack:** Sudden fluctuations in serum urate levels can precipitate or worsen a flare. 2. **Febuxostat:** A non-purine selective inhibitor of Xanthine Oxidase, used if Allopurinol is contraindicated or not tolerated. 3. **Probenecid:** Another common uricosuric; however, it is ineffective if the GFR is <50 mL/min. 4. **Drug of choice for Acute Gout:** NSAIDs (e.g., Indomethacin, Naproxen). If contraindicated (e.g., renal failure), use Corticosteroids.

Question 249: Which of the following is NOT an inhibitor of cyclooxygenase enzyme?

A. Aspirin
B. Warfarin (Correct Answer)
C. Phenylbutazone
D. Diclofenac

Explanation: ### Explanation **Correct Answer: B. Warfarin** **Why Warfarin is the correct answer:** Warfarin is an **oral anticoagulant**, not an anti-inflammatory drug. Its mechanism of action involves the inhibition of the enzyme **Vitamin K Epoxide Reductase (VKORC1)**. This prevents the gamma-carboxylation of Vitamin K-dependent clotting factors (**II, VII, IX, and X**) and proteins C and S. It has no inhibitory effect on the cyclooxygenase (COX) enzyme. **Why the other options are incorrect:** * **A. Aspirin:** An irreversible inhibitor of both COX-1 and COX-2. It acetylates a serine residue in the active site of the enzyme, leading to decreased synthesis of prostaglandins and thromboxane A2. * **C. Phenylbutazone:** A pyrazolone derivative and a non-selective COX inhibitor. While its clinical use is limited due to toxicity (e.g., agranulocytosis), it is a classic example of a traditional NSAID. * **D. Diclofenac:** A potent phenylacetic acid derivative that non-selectively inhibits COX-1 and COX-2. It is one of the most commonly used NSAIDs for pain and inflammation. **High-Yield Clinical Pearls for NEET-PG:** * **Aspirin unique feature:** It is the only NSAID that binds **irreversibly** to COX; all others are reversible inhibitors. * **Warfarin Monitoring:** Monitored using **PT/INR** (Prothrombin Time/International Normalized Ratio). * **Warfarin Teratogenicity:** It can cause **Fetal Warfarin Syndrome** (nasal hypoplasia, stippled epiphyses); hence, Heparin is preferred during pregnancy. * **COX-2 Selective Inhibitors:** Drugs like Celecoxib spare COX-1, reducing GI side effects but increasing the risk of cardiovascular thrombotic events.

Question 250: Pethidine is pharmacologically different from morphine because it

A. Causes more sedation
B. Causes more constipation
C. Has additional Anticholinergic action (Correct Answer)
D. Causes spasm of sphincter of Oddi

Explanation: Pethidine (Meperidine) is a synthetic opioid that differs from Morphine due to its unique chemical structure, which resembles Atropine. This structural similarity imparts significant **anticholinergic (antimuscarinic) properties** to Pethidine, which are absent in Morphine [2]. **Why Option C is Correct:** The additional anticholinergic action of Pethidine leads to several clinical differences: * **Mydriasis:** Unlike Morphine, which causes "pin-point pupils" (miosis), Pethidine can cause pupillary dilation or maintain a normal pupil size. * **Tachycardia:** It may cause an increase in heart rate, whereas Morphine typically causes bradycardia [2]. * **Dry Mouth:** Patients often experience more xerostomia. **Analysis of Incorrect Options:** * **A. Sedation:** Pethidine is generally **less sedating** than Morphine. At high doses or with chronic use, its metabolite (normeperidine) can cause CNS excitation, tremors, and seizures. * **B. Constipation:** Pethidine causes **less constipation** and has a shorter duration of action on the gastrointestinal tract compared to Morphine [1]. * **D. Spasm of Sphincter of Oddi:** While Pethidine does cause some contraction of smooth muscles, it causes **less spasm** of the Sphincter of Oddi than Morphine. Historically, this made it the preferred opioid for biliary colic (though NSAIDs are now first-line). **High-Yield Clinical Pearls for NEET-PG:** 1. **Metabolite Danger:** Pethidine is metabolized to **Normeperidine** [1], which is neurotoxic. It can cause **seizures**, especially in patients with renal failure [2]. 2. **Drug Interaction:** Pethidine is strictly contraindicated with **MAO Inhibitors** (e.g., Selegiline) as it can trigger a life-threatening **Serotonin Syndrome** (hyperpyrexia, delirium, convulsions). 3. **Obstetrics:** Pethidine is often preferred in labor because it does not delay uterine contractions as much as Morphine.

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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