Analgesics and Anti-inflammatory Drugs — MCQs

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

Question 121: Which of the following drugs is a full agonist at opioid receptors, has excellent oral bioavailability, is equipotent to morphine, and has a longer duration of action with milder withdrawal symptoms on abrupt discontinuation?

A. Fentanyl
B. Hydromorphone
C. Methadone (Correct Answer)
D. Nalbuphine

Explanation: The correct answer is **Methadone**. This drug is a synthetic µ-opioid receptor agonist with unique pharmacokinetic properties that make it ideal for opioid detoxification and maintenance programs [1]. **Why Methadone is correct:** * **Bioavailability:** Unlike morphine, which undergoes extensive first-pass metabolism, methadone has excellent oral bioavailability (approx. 80%) [1]. * **Potency:** It is roughly equipotent to morphine in chronic dosing [1]. * **Duration of Action:** It has a very long half-life (15–40 hours), leading to a prolonged duration of action [2]. * **Withdrawal Profile:** Because of its long half-life, the withdrawal symptoms upon abrupt discontinuation are **milder but more prolonged** compared to the intense, short-lived withdrawal seen with morphine or heroin. **Why other options are incorrect:** * **Fentanyl:** It is significantly more potent than morphine (approx. 100x) and has a very short duration of action when given parenterally [2]. * **Hydromorphone:** While a potent full agonist, it has a shorter half-life and more intense withdrawal symptoms than methadone [2]. * **Nalbuphine:** This is a **mixed agonist-antagonist** (κ-agonist and µ-antagonist). It exhibits a

Question 122: Which of the following drugs acts by inhibiting granulocyte migration?

A. Colchicine (Correct Answer)
B. Montelukast
C. Cromoglycate
D. Allopurinol

Explanation: **Explanation:** **Colchicine** is the correct answer because its primary mechanism of action involves binding to **tubulin**, a structural protein. This binding inhibits microtubule polymerization, which is essential for various cellular functions. In the context of acute gout, colchicine disrupts the formation of the mitotic spindle and cytoskeleton in neutrophils. This leads to the **inhibition of granulocyte migration** (chemotaxis) into the inflamed joint and reduces the phagocytosis of urate crystals, thereby halting the inflammatory cascade. **Analysis of Incorrect Options:** * **Montelukast:** This is a **Leukotriene Receptor Antagonist (LTRA)** that selectively blocks the CysLT1 receptor. It is used in the management of asthma and allergic rhinitis, not for inhibiting granulocyte migration. * **Cromoglycate:** This is a **Mast Cell Stabilizer**. It prevents the degranulation of mast cells and the subsequent release of histamine and leukotrienes; it does not directly affect granulocyte chemotaxis. * **Allopurinol:** This is a **Xanthine Oxidase Inhibitor** used for the chronic management of gout (hypouricemic therapy). It reduces the synthesis of uric acid but has no direct anti-inflammatory or anti-migratory effect during an acute attack. **High-Yield NEET-PG Pearls:** * **Drug of Choice:** While Colchicine is classic, **NSAIDs** (like Indomethacin) are currently the first-line treatment for acute gout due to the side-effect profile of colchicine. * **Toxicity:** The dose-limiting toxicity of Colchicine is **diarrhea** (gastrointestinal toxicity). * **Other Uses:** Colchicine is also used in Familial Mediterranean Fever (FMF), Behçet’s disease, and recurrent pericarditis. * **Contraindication:** It should be avoided in patients with severe renal or hepatic impairment.

Question 123: Which of the following is a TNF-alpha inhibitor used in the treatment of rheumatoid arthritis?

A. Infliximab (Correct Answer)
B. Rituximab
C. D-penicillamine
D. Cycloserine

Explanation: ### Explanation **Correct Answer: A. Infliximab** **Mechanism and Rationale:** Infliximab is a **chimeric monoclonal antibody** (composed of human and murine regions) that binds with high affinity to **Tumor Necrosis Factor-alpha (TNF-α)**. TNF-α is a key pro-inflammatory cytokine that mediates joint inflammation and destruction in Rheumatoid Arthritis (RA). By neutralizing both soluble and membrane-bound TNF-α, Infliximab reduces the infiltration of inflammatory cells into joints and slows radiological progression of the disease. **Analysis of Incorrect Options:** * **B. Rituximab:** This is a monoclonal antibody directed against the **CD20 antigen** found on the surface of B-lymphocytes. While used in RA, it is a B-cell depleting agent, not a TNF-alpha inhibitor. * **C. D-penicillamine:** This is a conventional synthetic Disease-Modifying Anti-Rheumatic Drug (csDMARD) and a chelating agent. Its use in RA has significantly declined due to toxicity (e.g., nephrotic syndrome, drug-induced lupus). * **D. Cycloserine:** This is a second-line **antitubercular drug** that inhibits bacterial cell wall synthesis. It has no role in the management of rheumatoid arthritis. **High-Yield Clinical Pearls for NEET-PG:** * **TNF-α Inhibitors Mnemonic:** "**A**ll **E**ngineers **I**nstall **G**iant **C**omputers" (**A**dalimumab, **E**tanercept, **I**nfliximab, **G**olimumab, **C**ertolizumab). * **Pre-treatment Screening:** Before starting any TNF-α inhibitor, patients **must** be screened for **Latent Tuberculosis** (via TST or IGRA) and Hepatitis B, as these drugs can cause reactivation. * **Etanercept** is unique because it is a **decoy receptor** (fusion protein), not a true monoclonal antibody. * Infliximab is typically administered via **IV infusion**, whereas most other biologics are given subcutaneously.

Question 124: Aspirin prolongs bleeding by inhibiting the synthesis of which of the following?

A. Adenosine receptors
B. Cyclic AMP
C. Prostacyclin
D. Thromboxane A2 (Correct Answer)

Explanation: ### Explanation **Correct Option: D. Thromboxane A2** Aspirin (Acetylsalicylic acid) is an irreversible inhibitor of the enzyme **Cyclooxygenase-1 (COX-1)**. In platelets, COX-1 is responsible for converting arachidonic acid into **Thromboxane A2 (TXA2)**. TXA2 is a potent vasoconstrictor and a key mediator of platelet aggregation. Because platelets are anucleated, they cannot synthesize new enzymes. Aspirin’s irreversible acetylation of COX-1 lasts for the entire lifespan of the platelet (approx. 7–10 days). By inhibiting TXA2 synthesis, aspirin prevents platelet plug formation, thereby prolonging bleeding time. --- ### Why the other options are incorrect: * **A. Adenosine receptors:** These are involved in coronary vasodilation and cardiac conduction (targeted by drugs like Adenosine or Caffeine), not the primary mechanism of aspirin. * **B. Cyclic AMP:** Increased levels of cAMP in platelets actually *inhibit* aggregation (the mechanism of drugs like Cilostazol or Dipyridamole). Aspirin does not work by decreasing cAMP. * **C. Prostacyclin (PGI2):** Produced by vascular endothelial cells, PGI2 *inhibits* platelet aggregation. While aspirin can inhibit PGI2 at high doses, its anti-platelet effect is specifically due to the suppression of TXA2. Endothelial cells can also resynthesize COX, unlike platelets. --- ### NEET-PG High-Yield Pearls: 1. **Low-dose Aspirin (75–150 mg):** Selectively inhibits TXA2, making it ideal for cardio-protection. 2. **Bleeding Time vs. Clotting Time:** Aspirin increases **Bleeding Time (BT)** but has no effect on Clotting Time (CT) or PT/APTT. 3. **Surgery Protocol:** Aspirin should ideally be stopped **7 days prior** to elective surgery to allow for the generation of new, functional platelets. 4. **Reye’s Syndrome:** Avoid aspirin in children with viral infections (Varicella/Influenza) due to the risk of fulminant hepatic failure and encephalopathy.

Question 125: Which of the following is an anti-inflammatory mediator?

A. Lipoxins (Correct Answer)
B. Thromboxane
C. Prostaglandins
D. Interleukins

Explanation: **Explanation:** The inflammatory response is a tightly regulated process involving both pro-inflammatory mediators that initiate the response and anti-inflammatory (pro-resolving) mediators that terminate it. **Why Lipoxins are correct:** Lipoxins (LXA4 and LXB4) are endogenous anti-inflammatory lipid mediators derived from arachidonic acid via the **lipoxygenase pathway**. Unlike leukotrienes, lipoxins act as "stop signals" for inflammation. They inhibit neutrophil chemotaxis and adhesion, decrease vascular permeability, and promote the non-phlogistic recruitment of monocytes/macrophages to clear apoptotic debris (efferocytosis). This process is essential for the **resolution phase** of inflammation. **Why the other options are incorrect:** * **Thromboxane (TXA2):** A potent pro-inflammatory mediator produced by platelets. It causes vasoconstriction and promotes platelet aggregation. * **Prostaglandins (e.g., PGE2, PGI2):** These are classic pro-inflammatory mediators. They cause vasodilation, increase vascular permeability, and sensitize pain receptors (hyperalgesia). * **Interleukins:** While a few interleukins (like IL-10) are anti-inflammatory, the term "Interleukins" generally refers to a broad class of cytokines (like IL-1, IL-6, and TNF-α) that are primarily responsible for driving the inflammatory cascade and fever. **High-Yield Clinical Pearls for NEET-PG:** * **Aspirin-Triggered Lipoxins (ATL):** Low-dose aspirin acetylates COX-2, diverting the pathway to produce "epi-lipoxins," which contribute to aspirin’s anti-inflammatory profile. * **Resolution Phase:** Other pro-resolving mediators include **Resolvins, Protectins, and Maresins** (derived from Omega-3 fatty acids). * **Dual Action:** Lipoxins are unique because they are produced through "transcellular biosynthesis" involving interactions between neutrophils and platelets/epithelial cells.

Question 126: What is true about anaphylactoid reactions caused by NSAIDs?

A. Caused by all NSAIDs.
B. COX-2 inhibitors are safe. (Correct Answer)
C. Related to hypersensitivity reaction.
D. Not related to inhibition of COX.

Explanation: **Explanation:** The "anaphylactoid" reaction (pseudo-allergy) caused by NSAIDs is not a true Type-I IgE-mediated hypersensitivity. Instead, it is a **pharmacological phenomenon** resulting from the inhibition of the **COX-1 enzyme**. **Why Option B is Correct:** When COX-1 is inhibited, the metabolism of arachidonic acid is diverted toward the **5-Lipoxygenase (5-LOX) pathway**. This leads to an overproduction of **cysteinyl leukotrienes**, which cause potent bronchoconstriction, vasodilation, and angioedema. Since **Selective COX-2 inhibitors** (e.g., Celecoxib, Etoricoxib) do not inhibit COX-1 at therapeutic doses, they do not trigger this leukotriene shift. Therefore, they are considered safe alternatives for patients with NSAID-induced asthma or urticaria. **Analysis of Incorrect Options:** * **Option A:** Not all NSAIDs cause this in all patients; it specifically occurs in "aspirin-sensitive" individuals (often associated with Samter’s Triad). * **Option C:** These are **anaphylactoid**, not anaphylactic. They do not involve prior sensitization or IgE antibodies; they occur due to direct biochemical mediator release. * **Option D:** The reaction is **directly related** to the inhibition of COX-1. **High-Yield Clinical Pearls for NEET-PG:** * **Samter’s Triad (Aspirin-Exacerbated Respiratory Disease):** Consists of Asthma, Nasal polyposis, and Aspirin intolerance. * **Drug of Choice:** For a patient with a history of NSAID-induced bronchospasm needing an analgesic, **Selective COX-2 inhibitors** or **Paracetamol** (in low doses, as it is a weak COX-1 inhibitor) are the preferred choices. * **Mechanism:** Shunting of arachidonic acid to the LOX pathway.

Question 127: Morphine is contraindicated in all of the following conditions except?

A. Pulmonary edema (Correct Answer)
B. Emphysema
C. Bronchial asthma
D. Head injury

Explanation: **Explanation:** **Correct Answer: A. Pulmonary edema** Morphine is not only indicated but is a **drug of choice** in the management of acute Left Ventricular Failure (LVF) and **Acute Pulmonary Edema**. Its therapeutic benefit is derived from its **venodilatory effect** (mediated by histamine release and reduced sympathetic tone), which increases venous capacitance. This reduces venous return (preload) and decreases pulmonary capillary pressure, providing rapid symptomatic relief from "air hunger." **Why the other options are contraindications:** * **B & C (Emphysema and Bronchial Asthma):** Morphine is a potent **respiratory depressant**. It reduces the sensitivity of the respiratory center to $CO_2$. In COPD/Emphysema, where the respiratory drive is already compromised, it can lead to fatal respiratory failure. In Asthma, morphine-induced **histamine release** can trigger bronchospasm, worsening the condition. * **D (Head Injury):** Morphine is strictly contraindicated in head injuries for two reasons: 1. It causes respiratory depression, leading to $CO_2$ retention. $CO_2$ is a potent vasodilator that **increases intracranial pressure (ICP)**, risking brain herniation. 2. It causes **miosis** (pin-point pupils), which interferes with the neurological monitoring of pupillary responses (a key sign of clinical worsening). **High-Yield Clinical Pearls for NEET-PG:** * **Biliary Colic:** Morphine is generally avoided because it causes constriction of the **Sphincter of Oddi**, potentially worsening the pain. Pethidine is often preferred. * **Antidote:** In case of morphine overdose (triad of miosis, coma, and respiratory depression), the specific antagonist is **Naloxone**. * **Mnemonic for Contraindications:** **"HEAD"** – **H**ead injury, **E**lderly/Endocrine (Myxedema), **A**sthma/COPD, **D**elivery (causes neonatal respiratory depression).

Question 128: Which of the following drugs is NOT used for analgesia in a patient with head injury?

A. Morphine (Correct Answer)
B. NSAIDs
C. Rofecoxib
D. Acetaminophen

Explanation: **Explanation:** The correct answer is **Morphine**. In patients with head injuries, opioids like Morphine are strictly contraindicated due to several critical physiological interactions: 1. **Respiratory Depression & ICP:** Morphine causes respiratory depression, leading to CO₂ retention (hypercapnia). CO₂ is a potent cerebral vasodilator; vasodilation increases cerebral blood volume, which further elevates **Intracranial Pressure (ICP)**, potentially leading to brain herniation. 2. **Miosis:** Morphine causes pupillary constriction (pin-point pupils). This masks the pupillary changes (like dilation) that clinicians use to monitor for neurological worsening or transtentorial herniation. 3. **Sedation:** It induces drowsiness and mental clouding, making it impossible to accurately assess the patient’s Glasgow Coma Scale (GCS) score. 4. **Emetic Effect:** It can cause vomiting, which further spikes ICP. **Why other options are incorrect:** * **NSAIDs (e.g., Ibuprofen) & Rofecoxib (COX-2 Inhibitor):** These do not cause respiratory depression or pupillary changes. While non-selective NSAIDs are sometimes avoided if there is a high risk of intracranial hemorrhage (due to anti-platelet effects), they do not carry the same absolute contraindication as opioids regarding ICP monitoring. * **Acetaminophen (Paracetamol):** This is the preferred analgesic in head injury cases as it provides effective pain relief without affecting the respiratory drive, pupil size, or neurological status. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of choice for pain in head injury:** Acetaminophen (Paracetamol). * **Opioid of choice if necessary:** Fentanyl is sometimes preferred over Morphine in ICU settings due to its shorter half-life, but generally, opioids are avoided. * **Triad of Opioid Poisoning:** Miosis, Respiratory Depression, and Coma.

Question 129: Which of the following is a selective COX-2 inhibitor?

A. Celecoxib (Correct Answer)
B. Indomethacin
C. Naproxen
D. All of the above

Explanation: **Explanation:**1. Why Celecoxib is correct:Non-Steroidal Anti-inflammatory Drugs (NSAIDs) are classified based on their selectivity for Cyclooxygenase (COX) enzymes. **Celecoxib** is a diaryl-substituted pyrazole that specifically binds to the distinct side pocket of the **COX-2** isoenzyme [1]. Unlike non-selective NSAIDs, it does not inhibit COX-1 at therapeutic concentrations. This selectivity preserves the cytoprotective prostaglandins in the gastric mucosa, significantly reducing the risk of peptic ulcers and GI bleeding [1, 2].2. Why other options are incorrect:* **Indomethacin:** It is a potent, **non-selective COX inhibitor** (acetic acid derivative). It is highly effective but associated with a high incidence of GI side effects and frontal headaches.* **Naproxen:** It is a propionic acid derivative and a **non-selective COX inhibitor**. It is often preferred in patients with high cardiovascular risk because it has a more favorable profile regarding platelet inhibition compared to other NSAIDs.* **Option D:** Incorrect because only Celecoxib exhibits COX-2 selectivity.3. NEET-PG High-Yield Clinical Pearls:* **The "Sulfa" Connection:** Celecoxib contains a sulfonamide moiety; use with caution in patients with known **sulfa allergies**.* **Cardiovascular Risk:** While selective COX-2 inhibitors (Coxibs) are "gastric-friendly," they lack anti-platelet activity (as platelets only express COX-1). This creates a pro-thrombotic state, increasing the risk of **Myocardial Infarction and Stroke** [1, 2].* **Etoricoxib:** This is the most COX-2 selective agent available globally [1].* **Therapeutic Use:** Celecoxib is often used in osteoarthritis, rheumatoid arthritis, and familial adenomatous polyposis (FAP) [1].

Question 130: All of the following statements regarding prostaglandins are true EXCEPT:

A. Leukotrienes cause vasoconstriction and decreased vascular permeability. (Correct Answer)
B. Prostaglandins are derived from 20-carbon unsaturated fatty acids.
C. Prostacyclin inhibits platelet aggregation.
D. Prostaglandins cause uterine muscle contraction and can induce labor.

Explanation: ### Explanation **1. Why Option A is the Correct Answer (The Exception):** Leukotrienes (specifically Cysteinyl Leukotrienes like **LTC4, LTD4, and LTE4**) are potent mediators of inflammation. While they do cause potent vasoconstriction in certain vascular beds, their hallmark effect on microvasculature is a **marked increase in vascular permeability** (especially in post-capillary venules), leading to exudation and edema. This is significantly more potent than histamine. Additionally, LTB4 is a major chemotactic agent for neutrophils. **2. Analysis of Incorrect Options:** * **Option B:** Prostaglandins are indeed eicosanoids, synthesized from **Arachidonic acid**, which is a **20-carbon polyunsaturated fatty acid** released from cell membrane phospholipids by Phospholipase A2. * **Option C:** **Prostacyclin (PGI2)**, produced by vascular endothelium, is a powerful vasodilator and the body’s primary **inhibitor of platelet aggregation**. It acts in physiological antagonism to Thromboxane A2 (TXA2). * **Option D:** **PGE2 and PGF2α** are potent stimulators of uterine smooth muscle. They increase the force and frequency of contractions throughout pregnancy and are used clinically for **induction of labor** (e.g., Dinoprostone) and medical abortion. **3. NEET-PG High-Yield Pearls:** * **Rate-limiting step:** Release of arachidonic acid by Phospholipase A2 (inhibited by Corticosteroids). * **PGE2 (Alprostadil):** Used to keep the **Ductus Arteriosus patent** in cyanotic heart disease. * **PGF2α (Latanoprost):** First-line treatment for **Glaucoma** (increases uveoscleral outflow). * **TXA2 vs. PGI2:** TXA2 (from platelets) causes aggregation/vasoconstriction; PGI2 (from endothelium) causes anti-aggregation/vasodilation. The balance between these two determines vascular homeostasis.

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

Practice Questions

Migraine Therapeutics

Practice Questions

Neuropathic Pain Management

Practice Questions

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