Analgesics and Anti-inflammatory Drugs — MCQs

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

Question 11: Alprostadil is indicated in which of the following conditions?

A. Erectile dysfunction (Correct Answer)
B. Postpartum hemorrhage (PPH)
C. Glaucoma
D. Cervical ripening

Explanation: **Explanation:** **Alprostadil** is a synthetic analogue of **Prostaglandin E1 (PGE1)**. It acts as a potent vasodilator and relaxes the smooth muscles of the *corpus cavernosum* by increasing intracellular cAMP levels. * **Why Option A is Correct:** In **Erectile Dysfunction (ED)**, Alprostadil is used as a second-line treatment (often when PDE-5 inhibitors like Sildenafil fail). It is administered via intracavernosal injection or intraurethral suppository to induce an erection by increasing local blood flow. * **Why Options B, C, and D are Incorrect:** * **Postpartum Hemorrhage (PPH):** The drug of choice is Oxytocin; however, the prostaglandin used here is **Carboprost (PGF2α)** or **Misoprostol (PGE1)**. * **Glaucoma:** The prostaglandins used to reduce intraocular pressure are **PGF2α analogues** like **Latanoprost**, Bimatoprost, and Travoprost. * **Cervical Ripening:** This is achieved using **Dinoprostone (PGE2)** or **Misoprostol (PGE1)**. **High-Yield Clinical Pearls for NEET-PG:** 1. **Ductus Arteriosus:** Apart from ED, Alprostadil is used to **maintain the patency of the Ductus Arteriosus** in neonates with cyanotic heart disease (e.g., Transposition of Great Arteries) until surgery can be performed. 2. **Misoprostol vs. Alprostadil:** While both are PGE1 analogues, Misoprostol is orally active and used for NSAID-induced peptic ulcers and obstetric indications, whereas Alprostadil is used for vascular/erectile indications. 3. **Side Effect:** The most significant risk of intracavernosal Alprostadil is **priapism** (prolonged, painful erection).

Question 12: Which of the following statements about bradykinin is true?

A. Causes pain (Correct Answer)
B. Causes bronchodilation
C. Causes vasoconstriction
D. Decreases vascular permeability

Explanation: **Explanation:** Bradykinin is a potent inflammatory nonapeptide belonging to the kinin system. It plays a central role in the pathophysiology of pain and inflammation. **1. Why Option A is Correct:** Bradykinin is one of the most potent endogenous algogenic (pain-producing) substances. It stimulates **B2 receptors** on sensory nerve endings (nociceptors), leading to the sensation of sharp, localized pain. Furthermore, it sensitizes these nerve endings to other stimuli (hyperalgesia) by stimulating the release of prostaglandins. **2. Why the Other Options are Incorrect:** * **B. Causes bronchodilation:** Incorrect. Bradykinin is a potent **bronchoconstrictor**, particularly in patients with asthma. It acts via B2 receptors to contract airway smooth muscle. * **C. Causes vasoconstriction:** Incorrect. Bradykinin is a powerful **vasodilator** in most vascular beds (via nitric oxide and PGI2 release). However, it does cause contraction of non-vascular smooth muscle (like the gut and bronchi). * **D. Decreases vascular permeability:** Incorrect. Bradykinin **increases vascular permeability** by causing contraction of endothelial cells in post-capillary venules, leading to edema (a hallmark of angioedema). **Clinical Pearls for NEET-PG:** * **ACE Inhibitors (ACEIs):** ACE (also known as Kinanase II) is responsible for the degradation of bradykinin. ACEIs lead to increased bradykinin levels, which is the primary cause of the **dry cough** and **angioedema** associated with these drugs. * **Icatibant:** A selective B2 receptor antagonist used in the treatment of acute attacks of Hereditary Angioedema (HAE). * **Receptors:** B1 receptors are induced during chronic inflammation, while B2 receptors are constitutively expressed and mediate most acute effects.

Question 13: Which opioid is contraindicated in patients taking MAO inhibitors?

A. Codeine
B. Morphine
C. Fentanyl (Correct Answer)
D. Buprenorphine

Explanation: ### Explanation **Correct Option: C. Fentanyl** The interaction between certain opioids and **Monoamine Oxidase Inhibitors (MAOIs)** can lead to a life-threatening condition known as **Serotonin Syndrome**. This occurs because some opioids act as weak serotonin reuptake inhibitors. When combined with MAOIs (which prevent the breakdown of serotonin), there is a massive accumulation of serotonin in the synaptic cleft. Fentanyl, along with **Pethidine (Meperidine)**, Tramadol, and Methadone, is known to have serotonergic activity. The interaction typically manifests as the "Excitatory Type" reaction, characterized by agitation, hyperpyrexia, muscular rigidity, and seizures. **Why other options are incorrect:** * **A. Codeine & B. Morphine:** These are phenanthrene derivatives. While they can cause a "Depressive Type" reaction (potentiation of opioid effects like respiratory depression) when used with MAOIs, they do not typically trigger Serotonin Syndrome. They are generally considered safer than Pethidine or Fentanyl in this context, though caution is still advised. * **D. Buprenorphine:** This is a partial mu-opioid agonist. It does not possess significant serotonergic activity and is not classically associated with the severe excitatory reactions seen with Fentanyl or Pethidine. **High-Yield NEET-PG Pearls:** 1. **Pethidine (Meperidine)** is the most notorious opioid for causing Serotonin Syndrome with MAOIs; however, Fentanyl is the most relevant potent synthetic opioid with this risk. 2. **Clinical Triad of Serotonin Syndrome:** Cognitive changes (agitation/confusion), Autonomic hyperactivity (tachycardia/hyperthermia), and Neuromuscular abnormalities (clonus/rigidity). 3. **Treatment:** Immediate discontinuation of offending agents and administration of **Cyproheptadine** (5-HT2A antagonist). 4. **Avoid "The Big Four" with MAOIs:** Pethidine, Fentanyl, Tramadol, and Dextromethorphan.

Question 14: The 00 opioid receptor is responsible for which of the following effects?

A. Miosis (Correct Answer)
B. Bradycardia
C. Hypothermia
D. Bronchodilation

Explanation: The **$\mu$ (Mu) opioid receptor** is the primary mediator for most clinical and adverse effects of opioid analgesics. ### **Explanation of the Correct Answer** **A. Miosis:** Opioids stimulate the **Edinger-Westphal nucleus** of the oculomotor nerve (CN III). This leads to parasympathetic overactivity, causing pupillary constriction (pinpoint pupils). Unlike many other opioid effects, tolerance does **not** develop to miosis, making it a reliable diagnostic sign of opioid overdose. ### **Analysis of Incorrect Options** * **B. Bradycardia:** While opioids can cause mild bradycardia via central vagal stimulation, this is more characteristic of the **$\kappa$ (Kappa)** receptor or specific drugs like Fentanyl. It is less a defining feature of the $\mu$ receptor compared to miosis. * **C. Hypothermia:** Opioids typically interfere with the thermoregulatory center in the hypothalamus. While $\mu$ receptors can cause a slight decrease in body temperature, **$\kappa$ receptors** are more specifically associated with significant hypothermia. * **D. Bronchodilation:** This is incorrect. Opioids can cause **bronchoconstriction** (especially Morphine) due to histamine release from mast cells. This is why Morphine is used with caution in bronchial asthma. ### **High-Yield NEET-PG Pearls** * **The "Rule of Two":** Tolerance does **not** develop to two specific opioid effects: **Miosis** and **Constipation**. * **$\mu$ Receptor Effects:** Supraspinal analgesia, respiratory depression (the most common cause of death in overdose), euphoria, and physical dependence. * **$\kappa$ Receptor Effects:** Spinal analgesia, miosis, dysphoria, and psychotomimetic effects (hallucinations). * **Diagnostic Triad of Opioid Poisoning:** Coma, Pinpoint pupils, and Respiratory depression.

Question 15: Which of the following drugs has the least gastrointestinal toxicity?

A. Indomethacin
B. Aspirin
C. Paracetamol (Correct Answer)
D. Phenylbutazone

Explanation: ### Explanation **Correct Answer: C. Paracetamol** **Mechanism and Rationale:** The primary reason **Paracetamol (Acetaminophen)** has the least gastrointestinal (GI) toxicity compared to the other options is its mechanism of action. Unlike traditional Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), paracetamol is a **poor inhibitor of cyclooxygenase (COX-1 and COX-2) in peripheral tissues** [1]. GI toxicity in NSAIDs is primarily due to the inhibition of **COX-1** in the gastric mucosa, which leads to a decrease in protective prostaglandins ($PGE_2$ and $PGI_2$). These prostaglandins are essential for maintaining the gastric mucosal barrier and stimulating bicarbonate secretion. Since paracetamol acts predominantly on the central nervous system (often attributed to COX-3 inhibition or modulation of the endocannabinoid system) and has negligible peripheral COX inhibition, it does not interfere with gastric mucosal protection [1]. **Analysis of Incorrect Options:** * **A. Indomethacin:** One of the most potent non-selective COX inhibitors. It has a very high incidence of GI side effects, including peptic ulcers and GI bleeding, as well as CNS side effects (frontal headaches). * **B. Aspirin:** An irreversible inhibitor of COX-1 and COX-2. It causes direct mucosal irritation and systemic inhibition of protective prostaglandins, making it highly gastrotoxic [2]. * **D. Phenylbutazone:** An older NSAID with significant toxicity profiles, including severe GI irritation and a high risk of bone marrow suppression (aplastic anemia). **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Paracetamol is the analgesic/antipyretic of choice for patients with peptic ulcer disease, bleeding disorders, or those on anticoagulants. * **Toxicity:** While safe for the GI tract, the limiting toxicity of Paracetamol is **Hepatotoxicity** (due to the metabolite NAPQI) [3]. The antidote is **N-acetylcysteine (NAC)** [3]. * **Anti-inflammatory effect:** Paracetamol has negligible anti-inflammatory activity because it is inactivated by peroxides present at sites of inflammation [1].

Question 16: Which of the following statements about cyclooxygenase-2 (COX-2) is true?

A. COX-2 is not inhibited by indomethacin.
B. COX-2 is inducible. (Correct Answer)
C. COX-2 generates cytoprotective prostaglandins in the gastric mucosa.
D. COX-2 is found only in fetal tissues.

Explanation: **Explanation:** The enzyme Cyclooxygenase (COX) exists in two primary isoforms: COX-1 and COX-2. Understanding their differences is high-yield for pharmacology. **1. Why Option B is Correct:** **COX-2 is an inducible enzyme.** While COX-1 is "constitutive" (constantly present in most tissues), COX-2 is normally absent or present in very low amounts. It is rapidly upregulated (induced) by inflammatory stimuli such as cytokines (IL-1, TNF-α), growth factors, and endotoxins. It is primarily responsible for synthesizing prostaglandins that mediate **pain, inflammation, and fever.** **2. Why the Other Options are Incorrect:** * **Option A:** Indomethacin is a **non-selective NSAID**. It inhibits both COX-1 and COX-2. Only "Coxibs" (like Celecoxib) are selective for COX-2. * **Option C:** This describes **COX-1**. COX-1 produces cytoprotective prostaglandins ($PGE_2$ and $PGI_2$) that maintain the gastric mucosal barrier and regulate renal blood flow. This is why non-selective NSAIDs cause gastric ulcers. * **Option D:** COX-2 is not limited to fetal tissues. While it is inducible in most places, it is **constitutively expressed** in specific adult organs, including the **Kidneys, Brain, and Spinal Cord.** **Clinical Pearls for NEET-PG:** * **The "Constitutive" Exception:** Remember that COX-2 is constitutive in the **Kidney** (macula densa) and **CNS**. This explains why selective COX-2 inhibitors can still cause renal side effects and hypertension. * **Cardiovascular Risk:** Selective COX-2 inhibitors (e.g., Rofecoxib) were associated with increased MI/Stroke risk because they inhibit $PGI_2$ (vasodilator/anti-aggregatory) in endothelium without inhibiting $TXA_2$ (vasoconstrictor/pro-aggregatory) in platelets (which is COX-1 dependent). * **Glucocorticoids:** These drugs exert their anti-inflammatory effect partly by inhibiting the expression of the COX-2 gene.

Question 17: Which of the following drugs inhibits xanthine oxidase?

A. Probenecid
B. Quiniarcine
C. Allopurinol (Correct Answer)
D. Sulfinpyrazone

Explanation: **Explanation:** **Correct Answer: C. Allopurinol** **Mechanism of Action:** Allopurinol is a structural analog of hypoxanthine [2]. It acts as a potent **competitive inhibitor of Xanthine Oxidase (XO)**, the enzyme responsible for converting hypoxanthine to xanthine and xanthine to uric acid [1]. Furthermore, allopurinol is metabolized by XO into **Alloxanthine (Oxypurinol)**, which is a non-competitive, long-acting inhibitor of the same enzyme (suicide inhibition) [1], [2]. By blocking this pathway, allopurinol reduces the synthesis of uric acid, making it the drug of choice for the chronic management of gout [4]. **Analysis of Incorrect Options:** * **A & D (Probenecid and Sulfinpyrazone):** These are **Uricosuric drugs**. They act on the renal tubules (inhibiting URAT-1) to block the reabsorption of uric acid, thereby increasing its excretion in urine [4]. They do not inhibit the production of uric acid. * **B (Quinacrine):** This is an older antimalarial and anthelmintic agent (used in Giardiasis). It has no role in the xanthine oxidase pathway. **High-Yield Clinical Pearls for NEET-PG:** * **Acute Gout Warning:** Never start Allopurinol during an acute attack of gout, as the sudden shift in serum urate levels can mobilize urate crystals from tissues and worsen the inflammation [2]. * **Drug Interactions:** Since **6-Mercaptopurine (6-MP)** and **Azathioprine** are metabolized by xanthine oxidase, co-administration with Allopurinol leads to their toxicity. The dose of these drugs must be reduced to 1/4th [3]. * **HLA-B*5801:** Testing for this allele is recommended in certain populations to prevent life-threatening hypersensitivity reactions like Stevens-Johnson Syndrome (SJS). * **Febuxostat:** A newer, non-purine selective inhibitor of xanthine oxidase.

Question 18: Pulse steroid therapy can be given in which of the following conditions?

A. Pemphigus vulgaris
B. Acute renal allograft rejection
C. Optic neuritis
D. All the above (Correct Answer)

Explanation: **Explanation:** **Pulse Steroid Therapy** refers to the administration of supra-pharmacological doses of glucocorticoids (typically **Methylprednisolone 500–1000 mg IV**) over a short period (usually 3–5 days). This technique aims to achieve a rapid, potent anti-inflammatory and immunosuppressive effect while minimizing the long-term side effects associated with chronic steroid use. **Why "All the Above" is Correct:** Pulse therapy is indicated in life-threatening or organ-threatening autoimmune and inflammatory conditions where immediate suppression of the immune system is required: * **Pemphigus Vulgaris:** High-dose steroids are the mainstay to control extensive blistering and prevent fatal fluid loss or secondary infections. * **Acute Renal Allograft Rejection:** It is the first-line treatment to reverse cellular rejection and salvage the transplanted organ. * **Optic Neuritis:** Specifically in Multiple Sclerosis-related cases, IV Methylprednisolone pulses accelerate the recovery of visual function (as per the ONTT trial). **Incorrect Options:** Since all three conditions are classic indications for pulse therapy, selecting any single option would be incomplete. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** **Methylprednisolone** is preferred over Dexamethasone due to its better tissue penetration and lower mineralocorticoid (salt-retaining) activity. * **Mechanism:** At these high doses, steroids work via **non-genomic mechanisms** (direct effects on cell membranes and mitochondrial function), providing a faster response than the standard genomic pathway. * **Side Effects to Watch:** Sudden cardiac arrhythmias (due to electrolyte shifts), acute psychosis, and hyperglycemia. * **Other Indications:** Systemic Lupus Erythematosus (SLE) with nephritis, Polyarteritis Nodosa (PAN), and Wegener’s Granulomatosis.

Question 19: Morphine withdrawal is characterized by all EXCEPT?

A. Miosis (Correct Answer)
B. Yawning
C. Lacrimation
D. Diarrhoea

Explanation: The correct answer is **A. Miosis**. Morphine withdrawal is characterized by a "rebound" phenomenon where the body’s physiological processes, previously suppressed by the opioid, become hyperactive. Morphine (an opioid agonist) causes **miosis** (pinpoint pupils) during acute action via stimulation of the Edinger-Westphal nucleus. Conversely, during **withdrawal**, the sympathetic nervous system becomes overactive, leading to **Mydriasis** (pupillary dilation), not miosis. [2] **Analysis of Options:** * **B. Yawning:** This is one of the earliest and most characteristic signs of opioid withdrawal, often accompanied by sneezing and rhinorrhea. [2] * **C. Lacrimation:** Excessive tearing (lacrimation) and sweating (diaphoresis) occur due to autonomic hyperactivity during the withdrawal phase. * **D. Diarrhoea:** Opioids are known to cause constipation by slowing GI motility. [1] During withdrawal, the GI tract becomes hypermotile, leading to abdominal cramps and profuse diarrhea. **Clinical Pearls for NEET-PG:** * **The "Cold Turkey" Sign:** Piloerection (goosebumps) occurs during withdrawal, giving the skin the appearance of a plucked turkey. [2] * **Miosis Exception:** While most opioids cause miosis, **Meperidine (Pethidine)** is an exception; it causes mydriasis due to its atropine-like (anticholinergic) action. [1] * **Treatment:** Acute withdrawal is managed with **Clonidine** (α2 agonist to reduce sympathetic overactivity) or substitution therapy with long-acting opioids like **Methadone** or **Buprenorphine**. * **Naloxone:** Administration of this antagonist in an opioid-dependent patient will precipitate "precipitated withdrawal," which is sudden and severe.

Question 20: Low-dose aspirin inhibits the formation of which substance?

A. Prostaglandin F2
B. Thromboxane A2 (Correct Answer)
C. Prostaglandin I2
D. All of the above

Explanation: ### Explanation **Mechanism of Action:** Aspirin (Acetylsalicylic acid) is an irreversible inhibitor of the enzyme **Cyclooxygenase (COX)**. It works by acetylating a serine residue at the active site of the enzyme. While high doses of aspirin inhibit both COX-1 and COX-2 globally, **low-dose aspirin (75–150 mg/day)** exhibits a preferential and irreversible inhibition of **COX-1 in platelets**. Platelets lack a nucleus and cannot synthesize new enzymes. Therefore, the inhibition of COX-1 lasts for the entire lifespan of the platelet (approx. 8–11 days). This prevents the conversion of arachidonic acid into **Thromboxane A2 (TXA2)**, a potent vasoconstrictor and platelet aggregator. This specific biochemical effect is the basis for aspirin’s use as an antiplatelet agent. **Analysis of Incorrect Options:** * **Option A (PGF2α):** While aspirin can inhibit the synthesis of various prostaglandins at higher anti-inflammatory doses, low-dose aspirin is specifically titrated to target platelet TXA2. * **Option C (PGI2/Prostacyclin):** PGI2 is produced by vascular endothelial cells. Unlike platelets, endothelial cells have nuclei and can regenerate new COX enzymes. Therefore, at low doses, the synthesis of PGI2 (a vasodilator and anti-aggregator) is relatively spared or only transiently affected, maintaining a favorable antithrombotic balance. * **Option D:** Incorrect because the selectivity for TXA2 is the hallmark of low-dose therapy. **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). * **Aspirin Triad (Samter’s Triad):** Asthma, Nasal polyposis, and Aspirin hypersensitivity. * **Primary Prevention:** Low-dose aspirin is used to reduce the risk of Myocardial Infarction (MI) and Stroke.

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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