Analgesics and Anti-inflammatory Drugs Practice Questions

Q: Ibuprofen acts by inhibiting which enzyme?

Cyclooxygenase. **Explanation:** **Mechanism of Action (Why B is correct):** Ibuprofen is a prototypical **Non-Steroidal Anti-Inflammatory Drug (NSAID)** belonging to the propionic acid derivative class. Its primary mechanism of action is the **reversible, non-selective inhibition of the enzyme Cyclooxygenase (COX-1 and COX-2)**. By inhibiting COX, ibuprofen prevents the conversion of arachidonic acid into prostaglandins (PGs), specifically PGE2 and PGI2. These prostaglandins are key mediators of inflammation, pain sensitization, and fever induction. **Analysis of Incorrect Options:** * **A. Lipooxygenase (LOX):** This enzyme converts arachidonic acid into leukotrienes. While drugs like Zileuton inhibit LOX, standard NSAIDs like Ibuprofen do not; in fact, inhibiting COX can sometimes "shunt" arachidonic acid toward the LOX pathway, potentially worsening asthma (aspirin-exacerbated respiratory disease). * **C & D. Resetting the thermostat/Increasing pain threshold:** These describe the **physiological effects** (antipyretic and analgesic actions) resulting from PG inhibition, but they are not the biochemical mechanism or the enzyme being inhibited. **High-Yield Clinical Pearls for NEET-PG:** * **Pharmacokinetics:** Ibuprofen has a short half-life (~2 hours), requiring frequent dosing. * **Clinical Use:** It is the drug of choice for closing a **Patent Ductus Arteriosus (PDA)** in neonates (though Indomethacin is also used). * **Adverse Effects:** Compared to Aspirin, Ibuprofen causes less gastric irritation but can still cause interstitial nephritis and fluid retention. * **Contraindication:** Avoid in patients with the "Aspirin Triad" (Asthma, Nasal polyps, and NSAID sensitivity).

Q: Which of the following drugs inhibits Thromboxane A2 synthase?

Dazoxiben. **Explanation:** The correct answer is **Dazoxiben**. **1. Why Dazoxiben is correct:** Dazoxiben is a selective **Thromboxane A2 (TXA2) synthase inhibitor**. In the arachidonic acid cascade, the enzyme TXA2 synthase converts Prostaglandin H2 (PGH2) into Thromboxane A2 (a potent vasoconstrictor and platelet aggregator). By inhibiting this specific enzyme, Dazoxiben reduces TXA2 levels without significantly affecting the production of other prostaglandins or prostacyclin (PGI2). This makes it pharmacologically distinct from non-selective COX inhibitors. **2. Why the other options are incorrect:** * **Aspirin:** It is an irreversible inhibitor of **Cyclooxygenase (COX-1 and COX-2)**. While it ultimately reduces TXA2 production by blocking the upstream synthesis of PGH2, it does not inhibit the TXA2 synthase enzyme itself. * **Prednisolone:** This is a glucocorticoid that acts much higher in the inflammatory cascade. It induces lipocortin (annexin A1), which inhibits **Phospholipase A2**, thereby preventing the release of arachidonic acid from cell membranes. * **Naproxen:** Like Aspirin, this is a non-selective **COX inhibitor** (reversible). It blocks the conversion of arachidonic acid to PGH2. **3. NEET-PG High-Yield Pearls:** * **Selective TXA2 Synthase Inhibitors:** Dazoxiben and Ridogrel (Ridogrel also has TXA2 receptor-blocking properties). * **Aspirin "Anti-platelet" Dose:** Low doses (75–150 mg) selectively inhibit COX-1 in platelets, leading to a permanent deficit in TXA2 for the life of the platelet (7–10 days). * **Prostacyclin (PGI2):** Produced by vascular endothelium; it is the physiological antagonist of TXA2 (causes vasodilation and inhibits aggregation). Selective TXA2 synthase inhibitors are theoretically superior to Aspirin because they spare PGI2 production.

Q: The Mu receptor of opioids is responsible for which of the following clinical actions?

Diuresis. This question focuses on the specific physiological effects mediated by opioid receptor subtypes. While Mu ($\mu$) receptors are the primary targets for clinical analgesia, they are associated with **urinary retention**, not diuresis. ### **Why "Diuresis" is the Correct Choice (The Exception)** In the context of this question, **Diuresis** is the correct answer because it is **NOT** an action of the Mu receptor. Mu receptors (specifically $\mu_2$) stimulate the release of Antidiuretic Hormone (ADH) and increase sphincter tone, leading to urinary retention. * **Clinical Concept:** Diuresis is uniquely associated with the **Kappa ($\kappa$) receptor**. Kappa agonists inhibit the release of ADH (vasopressin) at the posterior pituitary, leading to increased free water clearance. ### **Analysis of Incorrect Options (Mu Receptor Actions)** * **A. Analgesia:** This is the hallmark effect of Mu receptors ($\mu_1$ for supraspinal and $\mu_2$ for spinal analgesia). * **B. Respiratory Depression:** This is the most dangerous side effect of Mu receptor activation ($\mu_2$), caused by decreased sensitivity of the brainstem to $CO_2$. * **C. Sedation:** Mu and Kappa receptors both contribute to drowsiness and sedation, though Mu-mediated sedation is more profound. ### **High-Yield Clinical Pearls for NEET-PG** * **Mu ($\mu$) Receptor Effects:** Analgesia, Respiratory depression, Miosis (Pin-point pupil), Reduced GI motility (Constipation), Euphoria, and Physical dependence. * **Kappa ($\kappa$) Receptor Effects:** Spinal analgesia, **Diuresis**, Dysphoria, and Psychotomimetic effects (hallucinations). * **Delta ($\delta$) Receptor Effects:** Spinal/Supraspinal analgesia and modulation of Mu receptor activity. * **Mnemonic:** Remember **"K"** for **K**appa and **"K"** for **K**idneys (Diuresis). Most other classic opioid side effects (The "3 Cs": Constipation, Coma/Resp Depression, Convulsions) are Mu-mediated.

Q: Which of the following has a high oral to parenteral activity ratio?

Methadone. ### Explanation The **oral to parenteral (O:P) activity ratio** refers to the effectiveness of a drug when administered orally compared to its effectiveness when given by injection. A high ratio indicates high oral bioavailability and minimal first-pass metabolism. **1. Why Methadone is Correct:** Methadone is a synthetic opioid with **excellent oral bioavailability (approx. 80-90%)**. Because it undergoes minimal first-pass hepatic metabolism, its oral potency is nearly equal to its parenteral potency. This high O:P ratio, combined with its long half-life, makes it the gold standard for **opioid substitution therapy** and chronic pain management, as it provides stable plasma levels without the need for frequent injections. **2. Analysis of Incorrect Options:** * **Morphine:** It has a **low O:P ratio (approx. 1:3 to 1:6)**. It undergoes extensive significant first-pass metabolism in the liver (glucuronidation), meaning an oral dose must be much higher than an IV dose to achieve the same analgesic effect. * **Diacetylmorphine (Heroin):** This is a highly lipophilic prodrug. While it is more potent than morphine when injected (crossing the blood-brain barrier rapidly), it is deacetylated to morphine in the gut and liver when taken orally, leading to significant loss of potency. * **Oxymorphone:** Similar to morphine, it has low oral bioavailability (approx. 10%) due to extensive first-pass metabolism, necessitating much higher oral doses compared to parenteral administration. **3. NEET-PG High-Yield Pearls:** * **High O:P Ratio Drugs:** Methadone, Levorphanol, Codeine, and Oxycodone. * **Low O:P Ratio Drugs:** Morphine, Hydromorphone, and Oxymorphone. * **Methadone Mechanism:** It is a $\mu$-opioid receptor agonist, an **NMDA receptor antagonist**, and a monoamine reuptake inhibitor. * **Clinical Note:** Methadone is known for causing **QT interval prolongation**; baseline ECG is recommended before starting therapy.

Q: Which of the following effects is NOT caused by Platelet Activating Factor (PAF)?

Decreased vascular permeability. **Explanation:** Platelet Activating Factor (PAF) is a potent phospholipid autacoid derived from cell membranes. It plays a crucial role in inflammation, allergy, and anaphylaxis. **Why Option C is the correct answer:** PAF is one of the most potent agents known to **increase vascular permeability**. It causes the contraction of endothelial cells, leading to the formation of intercellular gaps. This results in the leakage of plasma proteins and fluid into the extravascular space (edema). Therefore, "Decreased vascular permeability" is the incorrect effect and the right answer to this question. **Analysis of Incorrect Options:** * **A. Bronchoconstriction:** PAF is a powerful bronchoconstrictor (about 1000 times more potent than histamine). It also induces bronchial hyperreactivity, a hallmark of asthma. * **B & D. Vasoconstriction and Vasodilation:** PAF has complex vascular effects. While it is a potent **vasodilator** in most vascular beds (leading to hypotension and shock), it can cause **vasoconstriction** in specific areas, such as the pulmonary and coronary arteries, depending on the dose and the underlying vascular tone. **High-Yield Clinical Pearls for NEET-PG:** * **Source:** Produced by platelets, neutrophils, monocytes, and endothelial cells via the action of Phospholipase A2. * **Potency:** It is significantly more potent than histamine in inducing wheal and flare reactions. * **Platelet Effects:** As the name suggests, it causes platelet aggregation and release of thromboxane A2. * **Antagonist:** **Ginkgolide B** (derived from the Ginkgo biloba tree) is a specific PAF receptor antagonist often mentioned in competitive exams.

Q: What is the drug of choice for acute gout?

Indomethacin. **Explanation:** The primary goal in managing **acute gout** is to control intense inflammation and pain. **NSAIDs** are currently considered the **first-line drug of choice** due to their efficacy and better safety profile compared to colchicine. Among NSAIDs, **Indomethacin** is traditionally the most frequently used agent. It works by inhibiting cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis and inhibiting urate crystal phagocytosis. **Analysis of Options:** * **A. Colchicine:** While highly effective, it is now considered **second-line** due to its narrow therapeutic index and significant gastrointestinal side effects (nausea, vomiting, abdominal cramps, and diarrhea). It is used if NSAIDs are contraindicated. * **C. Allopurinol:** This is a Xanthine Oxidase inhibitor used for **chronic gout** (prophylaxis). It should **never be started during an acute attack**, as a rapid drop in serum uric acid can mobilize urate crystals from tissues, potentially worsening or prolonging the acute episode. * **D. Dexamethasone:** Corticosteroids are reserved for patients who cannot tolerate NSAIDs or colchicine, or those with refractory polyarticular gout. **High-Yield Clinical Pearls for NEET-PG:** * **Treatment Sequence:** NSAIDs (1st line) → Colchicine (2nd line) → Corticosteroids (for resistant cases or renal failure). * **Aspirin Paradox:** Low-dose aspirin inhibits uric acid excretion (causing hyperuricemia), while high-dose aspirin is uricosuric. Therefore, aspirin is **avoided** in gout. * **Allopurinol Timing:** If a patient is already on Allopurinol when an acute attack starts, do not stop it; however, do not initiate it until the acute inflammation has subsided (usually 2 weeks later).

Q: Abatacept is used in the treatment of which of the following conditions?

Rheumatoid Arthritis. **Explanation:** **Abatacept** is a biological disease-modifying antirheumatic drug (bDMARD) used primarily in the treatment of **Rheumatoid Arthritis (RA)**, particularly in patients who have had an inadequate response to methotrexate or TNF inhibitors [1]. **Mechanism of Action:** Abatacept is a soluble fusion protein consisting of the extracellular domain of human **CTLA-4** linked to a modified Fc portion of human IgG1. It acts as a **T-cell costimulation modulator**. To activate a T-cell, two signals are required: 1. The TCR binding to the MHC-peptide complex. 2. The **CD28** on the T-cell binding to **CD80/86** on the Antigen Presenting Cell (APC). Abatacept binds to CD80/86 with high affinity, preventing it from binding to CD28, thereby inhibiting T-cell activation and the subsequent inflammatory cascade in RA [1]. **Analysis of Incorrect Options:** * **B. Asthma:** Managed with inhaled corticosteroids, beta-agonists, or biologics like Omalizumab (anti-IgE) or Mepolizumab (anti-IL-5). * **C. Paroxysmal Nocturnal Hemoglobinuria (PNH):** The drug of choice is **Eculizumab**, a monoclonal antibody against the complement protein C5. * **D. Autoimmune Hemolytic Anemia (AIHA):** Primarily treated with corticosteroids, immunosuppressants (Azathioprine/Mycophenolate), or Rituximab (anti-CD20). **High-Yield Clinical Pearls for NEET-PG:** * **Belatacept:** A related drug (higher affinity for CD80/86) used in **renal transplantation** to prevent graft rejection. * **Screening:** Always screen for **Latent TB** and Hepatitis B before starting Abatacept. * **Contraindication:** Do not combine Abatacept with TNF-alpha inhibitors (e.g., Etanercept, Infliximab) due to the significantly increased risk of serious infections [1]. **Note on Management:** Early use of DMARDs such as methotrexate is the mainstay of RA treatment, with progression to biological drugs if necessary [2].

Q: Which of the following is NOT an immunomodulator?

Cycloserine. **Explanation:** The correct answer is **Cycloserine** because it is an **antitubercular antibiotic**, not an immunomodulator. **1. Why Cycloserine is the correct answer:** Cycloserine is a second-line drug used in the treatment of multi-drug-resistant tuberculosis (MDR-TB). It acts by inhibiting the enzymes **D-alanine synthetase** and **alanine racemase**, thereby preventing bacterial cell wall synthesis. It has no primary role in modulating the immune system. **2. Why the other options are incorrect:** * **Tacrolimus (A) & Cyclosporin (B):** Both are **Calcineurin Inhibitors**. They bind to specific cytoplasmic proteins (FKBP-12 for Tacrolimus; Cyclophilin for Cyclosporin) to inhibit calcineurin. This prevents the dephosphorylation of NFAT (Nuclear Factor of Activated T-cells), leading to decreased production of IL-2 and other cytokines. * **Sirolimus (D):** Also known as Rapamycin, it is an **mTOR inhibitor**. It binds to FKBP-12 but, unlike Tacrolimus, it inhibits the "Mammalian Target of Rapamycin" (mTOR) pathway, blocking the cell cycle of T-cells in the G1-S phase. **Clinical Pearls for NEET-PG:** * **Cycloserine Side Effects:** Notable for **neurotoxicity** (seizures, psychosis). Pyridoxine (Vit B6) is often co-administered to reduce these effects. * **Gingival Hyperplasia:** A classic side effect of **Cyclosporin**, but notably **not** seen with Tacrolimus. * **Nephrotoxicity:** Both Cyclosporin and Tacrolimus are nephrotoxic, whereas Sirolimus is relatively non-nephrotoxic but can cause **hyperlipidemia and thrombocytopenia**. * **Drug of Choice:** Tacrolimus is generally preferred over Cyclosporin in solid organ transplantation due to higher potency and a better side-effect profile.

Q: Tolerance occurs to all side effects of Morphine, EXCEPT?

Constipation. **Explanation:** In chronic opioid therapy, the body develops **tolerance**—a state where increasing doses are required to achieve the same pharmacological effect [1]. This occurs due to the downregulation and desensitization of mu-opioid receptors [1]. However, tolerance does not develop uniformly across all organ systems [1],[2]. **Why Constipation is the Correct Answer:** Tolerance develops to most effects of Morphine, but there are **two notable exceptions: Constipation (miosis-inducing effect on the GI tract) and Miosis (pinpoint pupils) [2].** The enteric nervous system and the oculomotor nucleus (Edinger-Westphal nucleus) do not undergo the same receptor desensitization seen in the CNS [1]. Therefore, patients on long-term Morphine will continue to suffer from constipation regardless of the duration of use, often requiring prophylactic stimulant laxatives. **Analysis of Incorrect Options:** * **A. Sedation:** Tolerance to the sedative and "clouding" effects of Morphine develops relatively quickly (within days), allowing patients to remain alert while maintaining analgesia [1],[2]. * **C. Pain Relieving (Analgesia):** This is the most clinically significant area where tolerance occurs [1],[2]. Over time, higher doses are needed to manage the same level of pain. * **D. Euphoric Effect:** Addicts and patients experience a rapid decline in the "high" or euphoric sensation, leading to dose escalation [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic:** Remember **"Miosis and Constipation"** as the two "Persistent" side effects (No tolerance) [2]. * **Lethal Effect:** Tolerance also develops to **Respiratory Depression** [2]. This is why addicts can survive doses that would be fatal to a non-user. * **Mechanism:** Opioid-induced constipation (OIC) is primarily mediated by **$μ$-receptors in the myenteric plexus**, reducing gastric motility and secretions.

Question 1

Ibuprofen acts by inhibiting which enzyme?

Accepted Answer

Cyclooxygenase

Answer

Lipooxygenase

Answer

Resetting the hypothalamic thermostat

Answer

Increasing the pain threshold

Question 2

Which of the following drugs inhibits Thromboxane A2 synthase?

Accepted Answer

Dazoxiben

Answer

Aspirin

Answer

Prednisolone

Answer

Naproxen

Question 3

The Mu receptor of opioids is responsible for which of the following clinical actions?

Accepted Answer

Diuresis

Answer

Analgesia

Answer

Respiratory depression

Answer

Sedation

Question 4

Which of the following has a high oral to parenteral activity ratio?

Accepted Answer

Methadone

Answer

Morphine

Answer

Diacetyl morphine

Answer

Oxymorphine

Question 5

Which of the following effects is NOT caused by Platelet Activating Factor (PAF)?

Accepted Answer

Decreased vascular permeability

Answer

Bronchoconstriction

Answer

Vasoconstriction

Answer

Vasodilation

Question 6

What is the drug of choice for acute gout?

Accepted Answer

Indomethacin

Answer

Colchicine

Answer

Allopurinol

Answer

Dexamethasone

Question 7

What is the mechanism of action of colchicine in acute gout?

Accepted Answer

Deficiency of enzyme Xanthine oxidase

Answer

Uric acid nephrolithiasis.

Answer

Increase in serum urate concentration

Answer

Renal disease involving interstitial tissues

Question 8

Abatacept is used in the treatment of which of the following conditions?

Accepted Answer

Rheumatoid Arthritis

Answer

Asthma

Answer

Paroxysmal nocturnal hemoglobinuria

Answer

Autoimmune Hemolytic Anemia

Question 9

Which of the following is NOT an immunomodulator?

Accepted Answer

Cycloserine

Answer

Tacrolimus

Answer

Cyclosporin

Answer

Sirolimus

Question 10

Tolerance occurs to all side effects of Morphine, EXCEPT?

Accepted Answer

Constipation

Answer

Sedation

Answer

Pain relieving

Answer

Euphoric effect

Analgesics and Anti-inflammatory Drugs — MCQs

Analgesics and Anti-inflammatory Drugs — MCQs

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