Analgesics and Anti-inflammatory Drugs Practice Questions

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

Celecoxib. **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].

Q: In low doses, aspirin inhibits which of the following enzymes?

Cyclo-oxygenase. **Explanation:** Aspirin (Acetylsalicylic acid) is a non-steroidal anti-inflammatory drug (NSAID) that works by **irreversibly inhibiting the Cyclo-oxygenase (COX)** enzyme. It achieves this by acetylating a serine residue at the active site of the enzyme, thereby blocking the synthesis of prostaglandins and thromboxanes. **Why Option B is Correct:** Aspirin is unique among NSAIDs because of its irreversible action. In **low doses (75–150 mg/day)**, aspirin selectively inhibits **COX-1** in platelets. Since platelets are anucleated and cannot synthesize new enzymes, the inhibition lasts for the entire lifespan of the platelet (approx. 8–11 days), leading to its potent anti-platelet effect. **Why Other Options are Incorrect:** * **A. Lipoxygenase:** Aspirin does not inhibit the lipoxygenase (LOX) pathway. In fact, by blocking the COX pathway, arachidonic acid may be shunted toward the LOX pathway, potentially increasing leukotriene production (the mechanism behind aspirin-induced asthma). * **C & D. Thromboxane A2 and Prostaglandin I2:** These are **products** of the COX pathway, not enzymes themselves. While aspirin reduces the levels of TXA2 and PGI2, the question specifically asks for the *enzyme* being inhibited. **High-Yield Clinical Pearls for NEET-PG:** * **Zero-order kinetics:** Aspirin follows first-order kinetics at low doses but shifts to zero-order kinetics at high/toxic doses. * **Reye’s Syndrome:** Aspirin is contraindicated in children with viral infections (except in Kawasaki disease) due to the risk of hepatic encephalopathy. * **Aspirin Triad (Samter’s Triad):** Asthma, nasal polyposis, and aspirin hypersensitivity. * **Antidote for Salicylate poisoning:** Sodium bicarbonate (to alkalinize urine and promote excretion).

Q: A common side effect associated with all NSAID drugs is?

Gastric irritation. **Explanation:** The primary mechanism of action for Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) is the inhibition of the enzyme **Cyclooxygenase (COX)**. This prevents the conversion of arachidonic acid into prostaglandins (PGs). **Gastric irritation** is the most common side effect because NSAIDs inhibit **COX-1**, which is responsible for synthesizing "housekeeping" prostaglandins (**PGE2 and PGI2**) in the gastric mucosa. These prostaglandins are cytoprotective; they increase bicarbonate secretion, enhance mucosal blood flow, and promote mucus production. By inhibiting their synthesis, NSAIDs increase gastric acid secretion and weaken the mucosal barrier, leading to dyspepsia, erosions, and peptic ulcers. **Analysis of Incorrect Options:** * **Drowsiness:** This is not a characteristic side effect of NSAIDs. It is more commonly associated with opioid analgesics or first-generation antihistamines. * **Xerostomia (Dry mouth):** This is a classic anticholinergic side effect (e.g., Atropine, TCAs) and is not typically caused by NSAIDs. * **Constipation:** This is the most common gastrointestinal side effect of **Opioids** (due to decreased intestinal motility). In contrast, some NSAIDs (like Mefenamic acid) may actually cause diarrhea. **High-Yield Clinical Pearls for NEET-PG:** * **Selective COX-2 Inhibitors (e.g., Celecoxib):** Developed to reduce gastric irritation, but carry a higher risk of cardiovascular thrombotic events. * **Misoprostol:** A PGE1 analogue used to prevent NSAID-induced gastric ulcers. * **Aspirin Sensitivity:** Inhibition of COX can shift arachidonic acid metabolism toward the lipoxygenase (LOX) pathway, increasing leukotrienes and potentially triggering **aspirin-exacerbated respiratory disease (AERD)** or "Aspirin Asthma."

Q: All drugs are used in the management of psoriatic arthritis except?

Chloroquine. **Explanation:** The correct answer is **Chloroquine**. **Why Chloroquine is the correct answer:** Chloroquine and Hydroxychloroquine are Antimalarial drugs commonly used as DMARDs (Disease-Modifying Antirheumatic Drugs) for Rheumatoid Arthritis and SLE. However, they are **contraindicated or avoided in Psoriatic Arthritis** because they can trigger or significantly exacerbate skin lesions, leading to severe exfoliative dermatitis or "psoriasis flare-ups." Therefore, they are not used in the management of this condition. **Analysis of other options:** * **A. Methotrexate:** This is the first-line conventional synthetic DMARD for psoriatic arthritis. It effectively treats both the joint inflammation and the underlying skin psoriasis. * **B. Leflunomide:** An alternative conventional DMARD used in patients who cannot tolerate methotrexate. It inhibits dihydroorotate dehydrogenase and is effective for peripheral joint involvement in psoriatic arthritis. * **D. Abatacept:** A biological DMARD that acts as a T-cell costimulation modulator (CTLA-4 Ig). It is FDA-approved for the treatment of active psoriatic arthritis in adults. **Clinical Pearls for NEET-PG:** * **First-line treatment:** NSAIDs for mild cases; Methotrexate for moderate-to-severe disease. * **TNF-inhibitors:** (e.g., Etanercept, Adalimumab) are highly effective for both skin and joint symptoms. * **IL-17 Inhibitors:** (e.g., Secukinumab) are specifically high-yield for psoriatic arthritis management. * **Avoid:** Systemic corticosteroids are generally avoided in psoriasis due to the risk of life-threatening **pustular psoriasis** upon withdrawal.

Q: What is the loading dose of leflunomide in rheumatoid arthritis?

100 mg. **Explanation:** **Leflunomide** is a Disease-Modifying Antirheumatic Drug (DMARD) that acts by inhibiting the enzyme **dihydroorotate dehydrogenase (DHODH)**. This inhibition leads to the depletion of intracellular pyrimidine pools, thereby arresting the proliferation of activated T-cells. **Why 100 mg is correct:** Leflunomide has a very long half-life (approximately **2 weeks**) due to extensive enterohepatic circulation. To achieve therapeutic steady-state plasma concentrations rapidly, a **loading dose of 100 mg once daily for 3 consecutive days** is administered. Without this loading dose, it would take several weeks to reach effective levels. **Analysis of incorrect options:** * **10 mg & 20 mg:** These represent the standard **maintenance doses**. After the initial 3-day loading period, patients are typically transitioned to 20 mg daily (or 10 mg if the higher dose is not tolerated). * **400 mg:** This is an excessively high dose and is not used in standard rheumatological practice; it would significantly increase the risk of hepatotoxicity and gastrointestinal distress. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Pyrimidine synthesis inhibitor (DHODH inhibitor). * **Active Metabolite:** Malononitrilamide (MNA) / A77 1726. * **Washout Procedure:** Due to its long half-life, if a patient experiences toxicity or wishes to become pregnant, **Cholestyramine** is used to interrupt enterohepatic circulation and accelerate drug elimination. * **Contraindication:** It is highly **teratogenic** (Category X) and contraindicated in pregnancy. * **Monitoring:** Baseline and periodic Liver Function Tests (LFTs) are mandatory due to the risk of hepatotoxicity.

Question 1

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

Accepted Answer

Celecoxib

Answer

Indomethacin

Answer

Naproxen

Answer

All of the above

Question 2

All of the following statements regarding prostaglandins are true EXCEPT:

Accepted Answer

Leukotrienes cause vasoconstriction and decreased vascular permeability.

Answer

Prostaglandins are derived from 20-carbon unsaturated fatty acids.

Answer

Prostacyclin inhibits platelet aggregation.

Answer

Prostaglandins cause uterine muscle contraction and can induce labor.

Question 3

Administration of which of the following will alleviate respiratory depression caused by opioids, without blocking their analgesic effect?

Accepted Answer

5-HT agonist

Answer

Kappa-opioid antagonist

Answer

Delta-opioid antagonist

Answer

Adrenergic agonist

Question 4

All are true about cyclosporine-A EXCEPT?

Accepted Answer

It is too toxic to be given by the intravenous route and is generally administered orally.

Answer

It is indicated in renal transplantation.

Answer

It selectively inhibits T-lymphocyte proliferation.

Answer

It causes renal toxicity.

Question 5

In low doses, aspirin inhibits which of the following enzymes?

Accepted Answer

Cyclo-oxygenase

Answer

Lipoxygenase

Answer

Thromboxane A2

Answer

Prostaglandin I2

Question 6

A common side effect associated with all NSAID drugs is?

Accepted Answer

Gastric irritation

Answer

Drowsiness

Answer

Xerostomia

Answer

Constipation

Question 7

A 30-year-old male presents with sudden onset pain, swelling, and redness of the left first metatarsophalangeal joint. A needle aspirate of the joint shows needle-shaped, negatively birefringent crystals. The patient was prescribed a medication and returned the next day with nausea, vomiting, and diarrhea after taking it. Which of the following is the most likely medication that was prescribed?

Accepted Answer

Colchicine

Answer

Allopurinol

Answer

Steroids

Answer

Indomethacin

Question 8

All drugs are used in the management of psoriatic arthritis except?

Accepted Answer

Chloroquine

Answer

Methotrexate

Answer

Leflunomide

Answer

Abatacept

Question 9

What is the loading dose of leflunomide in rheumatoid arthritis?

Accepted Answer

100 mg

Answer

20 mg

Answer

10 mg

Answer

400 mg

Question 10

What is the plasma half-life of aspirin?

Accepted Answer

Longer for anti-inflammatory doses compared to analgesic doses

Answer

Independent of dose

Answer

Shorter for anti-inflammatory doses compared to analgesic doses

Answer

Can be increased by alkalinizing the urine

Analgesics and Anti-inflammatory Drugs — MCQs

Analgesics and Anti-inflammatory Drugs — MCQs

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