Analgesics and Anti-inflammatory Drugs Practice Questions

Q: Which of the following NSAIDs can cause hepatic necrosis if used in overdose?

Acetaminophen. **Explanation:** **Acetaminophen (Paracetamol)** is the correct answer because its toxicity is uniquely characterized by **centrilobular hepatic necrosis**. At therapeutic doses, acetaminophen is primarily metabolized via glucuronidation and sulfation. However, a small fraction is converted by Cytochrome P450 (CYP2E1) into a highly reactive toxic metabolite called **NAPQI** (*N-acetyl-p-benzoquinone imine*). In an overdose, the liver's glutathione stores are depleted, leaving NAPQI free to bind to hepatic cellular proteins, leading to oxidative stress and cell death. **Why the other options are incorrect:** * **Diclofenac sodium:** While it can cause idiosyncratic drug-induced liver injury (DILI) or a transient rise in transaminases, it is not classically associated with dose-dependent hepatic necrosis in the same mechanism as acetaminophen. * **Indomethacin:** This is a potent non-selective COX inhibitor primarily known for significant gastrointestinal toxicity, frontal headaches, and hematological side effects (neutropenia). * **Piroxicam:** An oxicam derivative with a long half-life, it is most notorious for causing a high incidence of gastric ulcers and skin reactions (Stevens-Johnson Syndrome). **High-Yield Clinical Pearls for NEET-PG:** * **Antidote:** **N-acetylcysteine (NAC)** is the specific antidote; it acts by replenishing glutathione stores and acting as a glutathione substitute. * **Rumack-Matthew Nomogram:** Used to predict hepatotoxicity risk based on plasma acetaminophen levels relative to the time of ingestion. * **Chronic Alcoholics:** They are at higher risk of toxicity even at lower doses because alcohol induces **CYP2E1**, leading to increased production of NAPQI. * **Toxicity Marker:** The earliest laboratory sign of liver damage in overdose is usually an elevation in **ALT/AST**, followed by an increased Prothrombin Time (PT/INR).

Q: Regarding COX-2, which of the following is its function?

Cell proliferation. Cyclooxygenase-2 (COX-2) is an inducible enzyme primarily expressed during inflammation, injury, or stress [1, 3]. Unlike COX-1, which is "constitutive" and maintains physiological functions (like gastric protection), COX-2 is associated with pathological states, including carcinogenesis [3, 4]. **Why Cell Proliferation is correct:** COX-2 plays a critical role in **cell proliferation** and the inhibition of apoptosis [2]. It catalyzes the synthesis of Prostaglandin E2 (PGE2), which activates signaling pathways (like the Wnt/β-catenin and MAPK pathways) that drive the cell cycle forward. Overexpression of COX-2 is frequently observed in various cancers, most notably **Colorectal Carcinoma** [3]. By promoting proliferation and angiogenesis while suppressing programmed cell death, COX-2 facilitates tumor growth [2]. **Analysis of Incorrect Options:** * **A, C, & D (Cell adhesion, migration, and differentiation):** While COX-2 can indirectly influence the tumor microenvironment (e.g., promoting metastasis via matrix metalloproteinases), its primary, direct enzymatic hallmark in the context of molecular pharmacology and pathology is the stimulation of **proliferation** [2]. Adhesion and differentiation are more closely regulated by integrins and specific transcription factors rather than the prostaglandin pathway. **High-Yield Clinical Pearls for NEET-PG:** * **Selective COX-2 Inhibitors (Celecoxib, Etoricoxib):** These drugs are preferred in patients with peptic ulcers because they spare the protective COX-1 in the stomach. * **Cardiovascular Risk:** COX-2 inhibitors increase the risk of MI and stroke because they inhibit PGI2 (vasodilator/anti-aggregatory) without affecting Thromboxane A2 (vasoconstrictor/pro-aggregatory) produced by COX-1. * **Cancer Prevention:** Regular use of Aspirin or NSAIDs is known to reduce the risk of colorectal polyps and cancer due to the inhibition of COX-2-mediated cell proliferation [3].

Q: Which of the following drugs does NOT have an anti-inflammatory effect?

Paracetamol. **Explanation:** The correct answer is **Paracetamol (Acetaminophen)**. While it is a potent analgesic and antipyretic, it lacks significant anti-inflammatory activity at therapeutic doses. **Why Paracetamol is the correct answer:** The primary mechanism of Paracetamol involves the inhibition of prostaglandin synthesis in the **Central Nervous System (CNS)**. However, it is a weak inhibitor of Cyclooxygenase (COX) in peripheral tissues. This is because Paracetamol is inactivated by **peroxides** produced at sites of inflammation. Since inflammation is a peroxide-rich environment, Paracetamol cannot effectively inhibit COX-1 or COX-2 peripherally, thus failing to exert an anti-inflammatory effect. **Why the other options are incorrect:** * **A. Ibuprofen:** A propionic acid derivative and non-selective COX inhibitor. It effectively reduces prostaglandin synthesis both centrally and peripherally, providing significant anti-inflammatory action. * **C. Diclofenac:** A potent phenylacetic acid derivative that inhibits COX-1 and COX-2. It is widely used for its strong anti-inflammatory properties in conditions like osteoarthritis and rheumatoid arthritis. * **D. Aspirin:** An irreversible inhibitor of COX enzymes. At higher doses, it is a classic anti-inflammatory agent used in rheumatic fever and Kawasaki disease. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Paracetamol is the preferred analgesic/antipyretic in children (to avoid **Reye’s Syndrome** associated with Aspirin) and in patients with peptic ulcers or bleeding disorders. * **Toxicity:** Overdose leads to **Centrilobular Hepatic Necrosis** due to the metabolite **NAPQI**. The antidote is **N-acetylcysteine (NAC)**, which replenishes glutathione stores. * **COX-3:** Some literature suggests Paracetamol may act on a splice variant of COX-1, often referred to as COX-3, primarily located in the cerebral cortex.

Q: Which NSAID lacks anti-inflammatory action?

Paracetamol. **Explanation:** The correct answer is **Paracetamol (Acetaminophen)**. **Why Paracetamol is the correct answer:** While Paracetamol is chemically classified as a non-steroidal drug with analgesic and antipyretic properties, it lacks significant **anti-inflammatory** activity. Its mechanism involves the inhibition of prostaglandin synthesis primarily in the **Central Nervous System (CNS)**. In peripheral tissues, its action is neutralized by **peroxides** produced at sites of inflammation. Since it does not effectively inhibit COX enzymes in the periphery, it cannot reduce tissue inflammation. **Why the other options are incorrect:** * **Ibuprofen & Diclofenac sodium:** These are traditional non-selective NSAIDs that inhibit both COX-1 and COX-2 enzymes in both the CNS and peripheral tissues. They are highly effective at reducing prostaglandin-mediated inflammation. * **Celecoxib:** This is a selective COX-2 inhibitor. Since COX-2 is the primary enzyme induced during the inflammatory response, Celecoxib possesses potent anti-inflammatory properties while minimizing GI side effects. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Paracetamol is the preferred analgesic/antipyretic in children (to avoid Reye’s syndrome associated with Aspirin) and in patients with peptic ulcers or bleeding disorders. * **Toxicity:** The toxic metabolite of Paracetamol is **NAPQI**. In overdose, it causes hepatic necrosis. * **Antidote:** **N-acetylcysteine (NAC)**, which replenishes glutathione stores. * **Phenacetin:** Paracetamol is the active metabolite of Phenacetin (withdrawn due to nephrotoxicity).

Q: The mu (u) opioid receptor is responsible for which of the following effects, except?

bronchodilation. **Explanation:** The **mu (μ) opioid receptor** is the primary mediator for most of the clinical and adverse effects of opioid analgesics (like Morphine). **Why "Bronchodilation" is the correct answer:** Opioids do **not** cause bronchodilation. In fact, they can cause **bronchoconstriction**. This occurs through two mechanisms: 1. **Central Respiratory Depression:** Mu receptors in the brainstem decrease the sensitivity of the respiratory center to CO2. 2. **Histamine Release:** Certain opioids (especially Morphine) trigger mast cell degranulation, leading to histamine release, which causes bronchospasm. Therefore, opioids should be used with caution in patients with bronchial asthma. **Analysis of Incorrect Options:** * **Miosis (A):** Mu and Kappa receptors stimulate the **Edinger-Westphal nucleus** (oculomotor nerve), leading to pupillary constriction (pinpoint pupils). This is a classic sign of opioid overdose. * **Bradycardia (B):** Opioids generally cause vagal stimulation and have a depressant effect on the sinoatrial (SA) node, leading to a decrease in heart rate. * **Hypothermia (C):** Mu receptor activation interferes with the hypothalamic thermoregulatory mechanisms, typically leading to a decrease in body temperature (though effects can vary with dosage and species). **High-Yield Clinical Pearls for NEET-PG:** * **Miosis & Constipation:** These are the two effects of opioids to which **tolerance never develops**. * **Triad of Opioid Overdose:** Coma, Pinpoint pupil, and Respiratory depression. * **Antidote:** **Naloxone** is the drug of choice for acute opioid poisoning (competitive antagonist at all opioid receptors). * **Exception:** Pethidine (Meperidine) is an opioid that causes **mydriasis** (due to its atropine-like action) rather than miosis.

Q: Aspirin produces all of the following effects except?

Constipation. **Explanation:** Aspirin (Acetylsalicylic acid) is a non-selective, irreversible inhibitor of Cyclooxygenase (COX-1 and COX-2) enzymes. The correct answer is **Constipation**, as Aspirin and other NSAIDs are more commonly associated with **diarrhea** or dyspepsia rather than constipation (which is a classic side effect of Opioid analgesics). **Why the other options are incorrect:** * **Frank gastric bleeding:** Aspirin inhibits COX-1, which is responsible for synthesizing protective prostaglandins ($PGE_2$ and $PGI_2$) in the gastric mucosa. Loss of these prostaglandins leads to increased acid secretion, reduced mucus production, and direct mucosal irritation, resulting in erosive gastritis and frank GI bleeding. * **Prolonged prothrombin time:** In high doses, Aspirin interferes with the synthesis of clotting factors (specifically Vitamin K-dependent factors) in the liver, leading to a functional hypoprothrombinemia and a prolonged Prothrombin Time (PT). * **Platelet dysfunction:** Aspirin irreversibly acetylates platelet COX-1, inhibiting the production of **Thromboxane $A_2$ ($TXA_2$)**, a potent platelet aggregator. Since platelets cannot synthesize new enzymes, this effect lasts for the entire lifespan of the platelet (approx. 7–10 days). **High-Yield Clinical Pearls for NEET-PG:** * **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:** Aspirin is contraindicated in children with viral infections (Flu/Varicella) due to the risk of fulminant hepatic failure and encephalopathy. * **Aspirin Triad (Samter’s Triad):** Asthma, Nasal polyposis, and Aspirin hypersensitivity. * **Toxicity:** Salicylism presents with **Tinnitus** (earliest sign), respiratory alkalosis, and metabolic acidosis. Management involves urinary alkalinization with Sodium Bicarbonate.

Q: Which of the following drugs does not possess any agonist action?

Nalmefene. ### Explanation The question tests the classification of opioid ligands based on their receptor activity. Opioids are categorized as pure agonists, mixed agonist-antagonists, or pure antagonists. **1. Why Nalmefene is the correct answer:** Nalmefene is a **pure opioid antagonist**. It is a derivative of naltrexone and acts as a competitive antagonist at $\mu$ (mu) and $\delta$ (delta) receptors, and a partial antagonist at $\kappa$ (kappa) receptors. Unlike the other options, it possesses **zero intrinsic activity** (no agonist action) at any opioid receptor. It is primarily used for treating alcohol dependence and opioid overdose due to its longer half-life compared to naloxone. **2. Why the other options are incorrect:** * **Buprenorphine:** It is a **partial $\mu$-agonist** and a $\kappa$-antagonist. Because it has partial agonist activity, it can precipitate withdrawal in opioid-dependent individuals but provides analgesia on its own. * **Butorphanol:** It is a **$\kappa$-agonist** and a $\mu$-antagonist (or partial agonist). Its primary analgesic effect is mediated through kappa receptors. * **Nalbuphine:** Similar to butorphanol, it acts as a **strong $\kappa$-agonist** and a $\mu$-antagonist. It is often used for obstetric analgesia. **3. High-Yield Clinical Pearls for NEET-PG:** * **Pure Antagonists:** Naloxone (IV, short-acting), Naltrexone (Oral, long-acting), and Nalmefene (IV/Oral, longest-acting). * **Buprenorphine** exhibits a "ceiling effect" for respiratory depression, making it safer in overdose, and is used in opioid substitution therapy. * **Mixed Agonist-Antagonists** (Butorphanol, Nalbuphine, Pentazocine) can precipitate withdrawal symptoms if administered to a patient already on a pure $\mu$-agonist like Morphine. * **Naloxone** is the drug of choice for acute opioid poisoning.

Question 1

Which of the following statements about Pentazocine is false?

Accepted Answer

Has a higher risk of addiction than morphine.

Answer

Causes decreased vomiting and constipation compared to morphine.

Answer

Has a lower risk of addiction than morphine.

Answer

Acts as an agonist-antagonist.

Question 2

Which of the following NSAIDs can cause hepatic necrosis if used in overdose?

Accepted Answer

Acetaminophen

Answer

Diclofenac sodium

Answer

Indomethacin

Answer

Piroxicam

Question 3

Regarding COX-2, which of the following is its function?

Accepted Answer

Cell proliferation

Answer

Cell adhesion

Answer

Cell migration

Answer

Cell differentiation

Question 4

Which of the following drugs does NOT have an anti-inflammatory effect?

Accepted Answer

Paracetamol

Answer

Ibuprofen

Answer

Diclofenac

Answer

Aspirin

Question 5

Which NSAID lacks anti-inflammatory action?

Accepted Answer

Paracetamol

Answer

Ibuprofen

Answer

Diclofenac sodium

Answer

Celecoxib

Question 6

Corticosteroids inhibit _______ to decrease the synthesis of prostaglandins?

Accepted Answer

Phospholipase - A2

Answer

Phospholipase - C

Answer

Lipoxygenase

Answer

Cyclo-oxygenase

Question 7

The mu (u) opioid receptor is responsible for which of the following effects, except?

Accepted Answer

bronchodilation

Answer

miosis

Answer

bradycardia

Answer

hypothermia

Question 8

Aspirin produces all of the following effects except?

Accepted Answer

Constipation

Answer

Frank gastric bleeding

Answer

Prolonged prothrombin time

Answer

Platelet dysfunction

Question 9

Which of the following actions of aspirin is manifested at the lowest dose?

Accepted Answer

Antiplatelet aggregatory

Answer

Analgesic

Answer

Antipyretic

Answer

Anti-inflammatory

Question 10

Which of the following drugs does not possess any agonist action?

Accepted Answer

Nalmefene

Answer

Buprenorphine

Answer

Butorphanol

Answer

Nalbuphine

Analgesics and Anti-inflammatory Drugs — MCQs

Analgesics and Anti-inflammatory Drugs — MCQs

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