Analgesics and Anti-inflammatory Drugs Practice Questions

Q: Naltrexone is:

Mu receptor antagonist. **Explanation:** **Naltrexone** is a potent, long-acting **pure opioid antagonist**. It works by competitively binding to opioid receptors with a very high affinity, thereby blocking the effects of endogenous and exogenous opioids. While it acts on Mu, Kappa, and Delta receptors, its primary clinical effect is mediated through the **antagonism of Mu (μ) receptors**. * **Why Option D is correct:** Naltrexone blocks the Mu receptor, preventing the euphoria and physical dependence associated with opioid use. Unlike Naloxone (which is used for acute overdose), Naltrexone has high oral bioavailability and a long half-life (approx. 10 hours), making it ideal for maintenance therapy. * **Why Options A, B, and C are incorrect:** Naltrexone does not activate (agonize) any opioid receptors. An agonist would produce morphine-like effects (analgesia, sedation, respiratory depression). Naltrexone specifically lacks intrinsic activity; it only occupies the receptor to prevent agonist binding. **Clinical Pearls for NEET-PG:** 1. **Indications:** Used for the **prevention of relapse** in detoxified opioid addicts and for **Alcohol Dependence** (it reduces alcohol craving by blocking the reward pathways mediated by endogenous opioids). 2. **Naltrexone vs. Naloxone:** Remember the mnemonic **"Nal-O-xone is for Overdose"** (IV/Intranasal, short-acting) and **"Naltrexone is for Maintenance"** (Oral, long-acting). 3. **Contraindication:** It should never be given to a patient currently dependent on opioids without detoxification, as it will precipitate **acute withdrawal syndrome**. 4. **Vivitrol:** This is the extended-release injectable form of Naltrexone given once monthly.

Q: Buprenorphine is a partial agonist of which receptor?

Mu receptor. **Explanation:** **Buprenorphine** is a unique semi-synthetic opioid derivative. It is classified as a **partial Mu (μ) receptor agonist** [2] and a **Kappa (κ) receptor antagonist**. 1. **Why Mu receptor is correct:** Buprenorphine binds with high affinity but low intrinsic activity to the Mu receptor [2], [3]. This results in a "ceiling effect" for respiratory depression and euphoria [1], making it safer in overdose compared to full agonists like morphine. However, due to its high binding affinity, it can displace full agonists, potentially precipitating withdrawal in opioid-dependent individuals [3]. 2. **Why other options are incorrect:** * **Kappa (κ) receptor:** Buprenorphine acts as an **antagonist** at this receptor. This antagonism is clinically significant as it contributes to its antidepressant effects and lack of psychotomimetic side effects (like dysphoria) typically associated with Kappa agonists. * **Delta (δ) receptor:** Buprenorphine has relatively low affinity/activity here; it is primarily considered an antagonist at Delta receptors. * **Sigma (σ) receptor:** This is no longer classified as a true opioid receptor. It is associated with hallucinations and dysphoria (seen with drugs like Pentazocine), but it is not the primary site of action for Buprenorphine. **High-Yield Clinical Pearls for NEET-PG:** * **Ceiling Effect:** Buprenorphine exhibits a ceiling effect for respiratory depression, enhancing its safety profile [1]. * **Opioid Substitution Therapy:** It is used in the management of opioid addiction (detoxification and maintenance) [1]. * **Naloxone Resistance:** Because Buprenorphine dissociates very slowly from Mu receptors, respiratory depression caused by it is difficult to reverse with standard doses of Naloxone [1]. * **Route:** It undergoes extensive first-pass metabolism, so it is administered **sublingually**, parenterally, or via transdermal patches [1].

Q: Phenylbutazone use as an NSAID is restricted because:

It has potential to cause agranulocytosis.. **Explanation:** **1. Why Option B is Correct:** Phenylbutazone is a pyrazolone derivative that was once widely used for its potent anti-inflammatory properties. However, its clinical use is now severely restricted (primarily to severe cases of ankylosing spondylitis or acute gout unresponsive to other treatments) due to its **idiosyncratic bone marrow toxicity**. The most serious adverse effect is **agranulocytosis** (and occasionally aplastic anemia), which can be fatal. Unlike dose-dependent side effects, this reaction is unpredictable and can occur even with short-term use, making the risk-benefit ratio unfavorable compared to newer NSAIDs. **2. Why Other Options are Incorrect:** * **Option A & C:** These are incorrect because Phenylbutazone is actually a **very potent** anti-inflammatory and analgesic agent. Its efficacy is comparable to or higher than many modern NSAIDs; the restriction is purely due to safety concerns, not lack of potency. * **Option D:** While Phenylbutazone does indeed cause significant drug interactions by displacing drugs (like warfarin or sulfonylureas) from plasma proteins and inhibiting their metabolism, this is a manageable clinical concern. It is not the primary reason for the near-total restriction of the drug; the life-threatening hematological toxicity (Option B) is the deciding factor. **3. High-Yield Clinical Pearls for NEET-PG:** * **Metabolite:** Oxyphenbutazone is the active metabolite of Phenylbutazone. * **Uricosuric Action:** Phenylbutazone has mild uricosuric properties, which is why it was historically used in gout. * **Sodium Retention:** It causes significant salt and water retention, making it contraindicated in patients with heart failure or hypertension. * **Exam Tip:** Whenever "Phenylbutazone" or "Metamizole (Analgin)" appears in NEET-PG, always look for **Agranulocytosis** as the key associated side effect.

Q: Which of the following drugs is useful in chronic gout but is NOT a uricosuric agent?

Allopurinol. ### Explanation **Correct Answer: D. Allopurinol** **1. Why Allopurinol is Correct:** Chronic gout is managed by lowering serum uric acid levels through two primary mechanisms: decreasing production or increasing excretion. **Allopurinol** is a **Xanthine Oxidase inhibitor**. It works by inhibiting the enzyme responsible for converting hypoxanthine to xanthine and xanthine to uric acid. Therefore, it reduces the *synthesis* of uric acid rather than increasing its renal excretion. It is the first-line drug for chronic gout, especially in "over-producers" of uric acid. **2. Why Other Options are Incorrect:** * **Probenecid (A):** This is a classic **uricosuric agent**. It inhibits the URAT1 transporter in the proximal convoluted tubule, blocking the reabsorption of uric acid and increasing its excretion in urine. * **Sulfinpyrazone (C):** Like probenecid, this is a potent **uricosuric agent** that inhibits renal tubular reabsorption of uric acid. * **Phenylbutazone (B):** This is an NSAID with weak uricosuric properties. While it has anti-inflammatory effects, it is rarely used today due to toxicity (e.g., agranulocytosis), but it technically falls into the category of drugs that increase uric acid excretion. **3. NEET-PG High-Yield Pearls:** * **Drug of Choice:** Allopurinol is the DOC for chronic gout in patients with renal impairment or a history of renal stones (where uricosurics are contraindicated). * **Hypersensitivity:** Watch for **HLA-B*5801** allele; patients with this gene are at high risk for Allopurinol Hypersensitivity Syndrome (SJS/TEN). * **Acute Attack Warning:** Never start Allopurinol during an acute attack of gout, as a sudden drop in serum urate can mobilize crystals from joints and worsen the inflammation. * **Drug Interaction:** Allopurinol inhibits the metabolism of **6-Mercaptopurine** and **Azathioprine**. If co-administered, the dose of these cytotoxic drugs must be reduced by 75%.

Q: All of the following are indications for eicosanoids or their inhibitors EXCEPT:

Essential hypertension. **Explanation:** The correct answer is **Essential Hypertension** because eicosanoids (prostaglandins) and their inhibitors are not standard or first-line treatments for this condition. While some prostaglandins have vasodilatory properties, they are not used clinically for essential hypertension due to their short half-life and significant side effects. **Analysis of Options:** * **Abortion:** Prostaglandin analogues like **Misoprostol (PGE1)** and **Dinoprostone (PGE2)** are used for medical termination of pregnancy and cervical ripening because they stimulate uterine contractions. * **Patent Ductus Arteriosus (PDA):** NSAIDs (eicosanoid inhibitors) like **Indomethacin** or **Ibuprofen** are the treatment of choice to close a PDA in neonates by inhibiting the synthesis of PGE2, which normally keeps the ductus open. * **Transposition of the Great Arteries:** In cyanotic heart defects, **Alprostadil (PGE1)** is used to **maintain** the patency of the ductus arteriosus. This allows for life-saving mixing of oxygenated and deoxygenated blood until surgical correction can be performed. **High-Yield Clinical Pearls for NEET-PG:** 1. **PGE1 (Alprostadil):** Used for maintaining PDA and treating erectile dysfunction. 2. **PGE1 Analogue (Misoprostol):** Used for NSAID-induced peptic ulcers and postpartum hemorrhage (PPH). 3. **PGF2α (Latanoprost):** First-line treatment for Open-Angle Glaucoma (increases uveoscleral outflow). 4. **PGI2 (Epoprostenol):** Used in Pulmonary Arterial Hypertension. 5. **TXA2 (Thromboxane):** Potent vasoconstrictor and platelet aggregator; inhibited by low-dose Aspirin for cardioprotection.

Q: What is the best drug for chronic gout in a patient with renal impairment?

Allopurinol. **Explanation:** **1. Why Allopurinol is the Correct Answer:** Allopurinol is a **Xanthine Oxidase Inhibitor** that reduces the production of uric acid. In chronic gout management, it is considered the first-line urate-lowering therapy (ULT) regardless of renal function. While allopurinol metabolites are excreted renally, it remains the drug of choice in renal impairment because its dose can be safely **titrated downwards** (starting at ≤100 mg/day) to achieve target serum urate levels while monitoring for toxicity. Unlike uricosurics, its efficacy does not depend on renal clearance of uric acid. **2. Why the Other Options are Incorrect:** * **Naproxen (NSAID):** NSAIDs are used for acute gouty attacks, not chronic management. Furthermore, they are generally **contraindicated** in significant renal impairment due to the risk of acute kidney injury and fluid retention. * **Probenecid & Sulfinpyrazone (Uricosurics):** These drugs work by inhibiting the reabsorption of uric acid in the proximal tubule. They are **ineffective** when the Glomerular Filtration Rate (GFR) is low (typically <30–50 mL/min) because they cannot reach their site of action in the tubular lumen. They also increase the risk of uric acid nephrolithiasis. **3. High-Yield Clinical Pearls for NEET-PG:** * **Febuxostat:** Another Xanthine Oxidase Inhibitor; it is metabolized by the liver and is a preferred alternative if allopurinol is not tolerated in renal patients. * **HLA-B*5801:** Testing for this allele is recommended before starting Allopurinol in high-risk populations (e.g., Han Chinese, Thai) to prevent **Stevens-Johnson Syndrome/TEN**. * **Acute Attack Prophylaxis:** When starting Allopurinol, always co-administer low-dose colchicine or NSAIDs for 3–6 months to prevent "mobilization flares."

Q: Which of the following disease-modifying antirheumatic drugs (DMARDs) requires regular liver function testing?

Methotrexate. **Explanation:** **Methotrexate (MTX)** is the "anchor drug" and first-line DMARD for Rheumatoid Arthritis. It acts as a folic acid antagonist, inhibiting dihydrofolate reductase. Its primary dose-limiting toxicity is **hepatotoxicity**, which can range from transient elevation of transaminases to chronic fibrosis and cirrhosis. Therefore, regular monitoring of **Liver Function Tests (LFTs)**, along with Complete Blood Counts (CBC) and serum creatinine, is mandatory (typically every 2–4 weeks initially, then every 3 months). **Analysis of Incorrect Options:** * **Infliximab:** A TNF-α inhibitor. While it carries a risk of reactivation of latent Tuberculosis and infusion reactions, it does not routinely require frequent LFT monitoring compared to MTX. * **Abatacept:** A T-cell costimulation modulator (CTLA-4 Ig). Its main concerns are increased risk of infections and COPD exacerbations, rather than primary hepatotoxicity. * **Cyclophosphamide:** An alkylating agent used in severe systemic vasculitis or lupus nephritis. Its hallmark toxicity is **hemorrhagic cystitis** (prevented by Mesna and hydration) and bone marrow suppression; monitoring focuses on urinalysis and CBC. **High-Yield Clinical Pearls for NEET-PG:** * **Rescue Therapy:** Leucovorin (folinic acid) is used to rescue normal cells from MTX toxicity. * **Supplementation:** Daily Folic acid (1–5 mg) reduces MTX-induced GI side effects and hepatotoxicity without compromising efficacy. * **Contraindication:** MTX is strictly **teratogenic** (Category X); it must be stopped at least 3 months before conception in both men and women. * **Leflunomide:** Another DMARD that also requires regular LFT monitoring due to significant hepatotoxicity.

Q: Which of the following antihistamines has very few cholinergic side effects?

Loratidine. **Explanation:** The core concept behind this question is the classification of antihistamines into **First-generation** and **Second-generation** agents based on their selectivity and ability to cross the blood-brain barrier. **Why Loratadine is correct:** Loratadine is a **second-generation H1-antihistamine**. Unlike first-generation drugs, second-generation agents are highly selective for peripheral H1 receptors and have minimal affinity for cholinergic (muscarinic), adrenergic, or serotonergic receptors. Furthermore, they are large, lipophobic molecules that do not cross the blood-brain barrier significantly, resulting in a lack of central anticholinergic effects (like sedation) and peripheral effects (like dry mouth or urinary retention). **Analysis of Incorrect Options:** * **Promethazine (Option A):** A first-generation antihistamine (phenothiazine group) with potent anticholinergic and sedative properties. It is often used for motion sickness and as a pre-anesthetic medication due to these effects. * **Chlorpheniramine (Option B):** A common first-generation agent found in cough syrups. It possesses significant anticholinergic activity, often leading to sedation and dryness of mucous membranes. * **Hydroxyzine (Option C):** A first-generation agent with high anticholinergic and sedative potency, frequently used for its anxiolytic and antipruritic properties. **NEET-PG High-Yield Pearls:** * **Second-generation antihistamines:** Loratadine, Cetirizine, Fexofenadine, Desloratadine, and Azelastine. * **Fexofenadine** is the active metabolite of Terfenadine and is considered the least sedating antihistamine. * **Terfenadine and Astemizole** were withdrawn from the market because they cause **QT prolongation (Torsades de Pointes)** when co-administered with CYP3A4 inhibitors (like Ketoconazole or Erythromycin). * **Cetirizine** is a second-generation drug that may still cause mild sedation in some patients compared to Loratadine.

Question 1

Naltrexone is:

Accepted Answer

Mu receptor antagonist

Answer

Mu receptor agonist

Answer

Delta receptor agonist

Answer

Kappa receptor agonist

Question 2

Buprenorphine is a partial agonist of which receptor?

Accepted Answer

Mu receptor

Answer

Delta receptor

Answer

Kappa receptor

Answer

Sigma receptor

Question 3

Phenylbutazone use as an NSAID is restricted because:

Accepted Answer

It has potential to cause agranulocytosis.

Answer

It has lower anti-inflammatory efficacy than other NSAIDs.

Answer

It has weak analgesic action.

Answer

It alters the protein binding and metabolism of many drugs.

Question 4

Which of the following drugs is useful in chronic gout but is NOT a uricosuric agent?

Accepted Answer

Allopurinol

Answer

Probenecid

Answer

Phenylbutazone

Answer

Sulfinpyrazone

Question 5

All of the following are indications for eicosanoids or their inhibitors EXCEPT:

Accepted Answer

Essential hypertension

Answer

Abortion

Answer

Patent ductus arteriosus

Answer

Transposition of the great arteries

Question 6

What is the best drug for chronic gout in a patient with renal impairment?

Accepted Answer

Allopurinol

Answer

Naproxen

Answer

Probenecid

Answer

Sulfinpyrazone

Question 7

Which of the following disease-modifying antirheumatic drugs (DMARDs) requires regular liver function testing?

Accepted Answer

Methotrexate

Answer

Infliximab

Answer

Abatacept

Answer

Cyclophosphamide

Question 8

Which of the following statements is not true about NSAIDs?

Accepted Answer

Its clearance is independent of plasma concentration.

Answer

Acetylsalicylic acid is an irreversible inhibitor of the Cox enzyme.

Answer

Acetylsalicylic acid reduces in vivo synthesis of prostaglandins.

Answer

The antiplatelet effect of low-dose aspirin is related to presystemic Cox inhibition.

Question 9

As compared to morphine, methadone is considered to be:

Accepted Answer

A superior analgesic and an inferior hypnotic

Answer

An inferior hypnotic and a superior analgesic

Answer

A superior analgesic and a superior hypnotic

Answer

An inferior analgesic and an inferior hypnotic

Question 10

Which of the following antihistamines has very few cholinergic side effects?

Accepted Answer

Loratidine

Answer

Promethazine

Answer

Chlorpheniramine

Answer

Hydroxyzine

Analgesics and Anti-inflammatory Drugs — MCQs

Analgesics and Anti-inflammatory Drugs — MCQs

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