Analgesics and Anti-inflammatory Drugs — MCQs

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

Question 111: Which of the following is a disease-modifying antirheumatic drug (DMARD) commonly used in rheumatoid arthritis?

A. Azathioprine
B. Hydroxychloroquine
C. Methotrexate (Correct Answer)
D. Leflunomide

Explanation: **Explanation:** **Methotrexate (MTX)** is considered the **"Anchor Drug"** and the first-line Disease-Modifying Antirheumatic Drug (DMARD) for Rheumatoid Arthritis (RA). Its primary mechanism in RA is the inhibition of **aminoimidazole-4-carboxamide ribonucleotide (AICAR) transformylase**, leading to increased extracellular adenosine, which exerts potent anti-inflammatory effects. At higher doses (used in oncology), it inhibits dihydrofolate reductase (DHFR). It is preferred due to its efficacy, favorable cost-profile, and ability to reduce radiologic progression of the disease. **Analysis of Options:** * **A. Azathioprine:** While it has DMARD properties, it is generally reserved for refractory cases or systemic involvement (like vasculitis) due to its toxicity profile. It is not a first-line conventional synthetic DMARD (csDMARD). * **B. Hydroxychloroquine:** This is a "mild" DMARD. It is often used in very early/mild RA or as part of "Triple Therapy" (MTX + Sulfasalazine + HCQ), but it is rarely used as monotherapy for aggressive disease because it does not reliably prevent bone erosions. * **D. Leflunomide:** This is an effective DMARD that inhibits **dihydroorotate dehydrogenase**, arresting pyrimidine synthesis. While it is a valid alternative to Methotrexate, MTX remains the gold standard and the most "commonly used" initial therapy. **High-Yield Clinical Pearls for NEET-PG:** * **Supplementation:** Always co-prescribe **Folic acid** (5 mg/week) to reduce MTX side effects like mucosal ulcers and GI upset. * **Monitoring:** Monitor Liver Function Tests (LFTs) due to the risk of hepatic fibrosis and CBC for myelosuppression. * **Contraindications:** MTX is strictly **contraindicated in pregnancy** (Teratogenic). * **Fast Fact:** MTX is usually administered as a **once-weekly dose**, not daily.

Question 112: Which of the following statements regarding naltrexone is true?

A. It is an opioid antagonist.
B. It is used in alcohol dependence.
C. It is used to treat opioid dependence.
D. All of the above. (Correct Answer)

Explanation: **Explanation:** Naltrexone is a long-acting, competitive **opioid receptor antagonist** with high affinity for $\mu$-receptors. Its clinical utility stems from its ability to block the pharmacological effects of both exogenous opioids and endogenous endorphins. * **Option A (Opioid Antagonist):** Naltrexone binds to opioid receptors without activating them, effectively blocking the effects of agonists like morphine or heroin. Unlike naloxone, it has high oral bioavailability and a long half-life (approx. 10 hours), making it suitable for maintenance therapy rather than acute overdose. * **Option B (Alcohol Dependence):** It is FDA-approved for alcohol use disorder. It works by blocking the $\mu$-opioid receptors involved in the reward pathway, thereby reducing the "high" or euphoria associated with alcohol consumption and decreasing cravings. * **Option C (Opioid Dependence):** It is used for **relapse prevention** in patients who have already undergone detoxification. By blocking the effects of opioids, it prevents the reinforcing "rush" if a patient slips, helping to extinguish drug-seeking behavior. **High-Yield Clinical Pearls for NEET-PG:** * **Naltrexone vs. Naloxone:** Remember **"Naloxone is for Now"** (acute overdose, IV, short-acting) and **"Naltrexone is for Next"** (maintenance/chronic use, Oral, long-acting). * **Contraindication:** Never initiate naltrexone until a patient is opioid-free for 7–10 days to avoid precipitating **severe withdrawal syndrome**. * **Nalmefene:** Another long-acting antagonist similar to naltrexone but with a longer half-life and better oral absorption. * **Methylnaltrexone:** A peripheral antagonist used specifically for opioid-induced constipation (does not cross the BBB).

Question 113: Short-acting synthetic opioid is

A. Fentanyl
B. Remifentanil (Correct Answer)
C. Alfentanil
D. Sufentanil

Explanation: **Explanation:** The correct answer is **Remifentanil**. The primary medical concept here is the **metabolism and duration of action** of synthetic opioids. Remifentanil is unique among opioids because it contains an **ester linkage**. This allows it to be rapidly metabolized by **non-specific plasma and tissue esterases**, rather than relying on hepatic metabolism. Consequently, it has an ultra-short half-life (approximately 3–10 minutes) and a predictable, rapid recovery profile that is independent of the duration of infusion (context-sensitive half-life). **Analysis of Options:** * **Remifentanil (Correct):** The shortest-acting opioid due to rapid esterase hydrolysis. It is ideal for procedures requiring intense analgesia with immediate recovery. * **Fentanyl:** A potent synthetic opioid, but it is highly lipid-soluble and undergoes hepatic metabolism. It has a longer duration of action compared to remifentanil. * **Alfentanil:** While it has a faster *onset* than fentanyl due to its low pKa (more unionized drug), its duration of action is longer than remifentanil. * **Sufentanil:** The most potent of the group (5–10x more than fentanyl), but it has a longer duration of action and a tendency for accumulation in fatty tissues. **High-Yield Clinical Pearls for NEET-PG:** * **Context-Sensitive Half-Life:** Remifentanil has the shortest context-sensitive half-life, making it the drug of choice for Total Intravenous Anesthesia (TIVA). * **Metabolism:** Remifentanil is the only opioid not significantly affected by hepatic or renal failure. * **Potency Order:** Sufentanil > Remifentanil > Fentanyl > Alfentanil > Morphine. * **Side Effect:** Rapid administration of these synthetic opioids can cause **Chest Wall Rigidity** (Wooden Chest Syndrome), which may require muscle relaxants for management.

Question 114: A 74-year-old man reports having multiple gout attacks of his left big toe. He is symptom-free currently and is prescribed allopurinol for gout prophylaxis. Which of the following is the most likely mechanism of action for this medication?

A. Increasing uric acid production
B. Blocking excretion of uric acid by renal tubular mechanism
C. Inhibiting xanthine oxidase (Correct Answer)
D. Diminishing inflammation of acute gouty arthritis

Explanation: **Explanation:** **Mechanism of Action (Correct Answer: C)** Allopurinol is a purine analog that acts as a competitive inhibitor of **Xanthine Oxidase (XO)**. Under normal physiological conditions, XO catalyzes the oxidation of hypoxanthine to xanthine and xanthine to **uric acid**. By inhibiting this enzyme, allopurinol reduces the plasma concentration and urinary excretion of uric acid, thereby preventing the formation of urate crystals in joints and tissues. **Analysis of Incorrect Options:** * **Option A:** This is counter-therapeutic; the goal of gout management is to decrease, not increase, uric acid levels. * **Option B:** This describes **Uricosurics** (e.g., Probenecid, Lesinurad), which inhibit the URAT1 transporter in the proximal tubule to increase excretion. Allopurinol actually decreases the total urate load. * **Option C:** This describes the mechanism of **Colchicine** (inhibits microtubule polymerization) or **NSAIDs** (COX inhibition), which are used for acute attacks. Allopurinol has no anti-inflammatory or analgesic activity and can actually precipitate an acute attack if started without prophylaxis. **High-Yield NEET-PG Pearls:** * **Active Metabolite:** Allopurinol is metabolized by XO into **Alloxanthine (Oxypurinol)**, which is a long-acting, non-competitive inhibitor of the same enzyme. * **Drug Interactions:** Since XO metabolizes **6-Mercaptopurine (6-MP)** and **Azathioprine**, co-administration with Allopurinol leads to toxic levels of these immunosuppressants. Doses must be reduced by 50-75%. * **HLA-B*5801:** Testing is recommended in certain populations (e.g., Han Chinese, Thai) to prevent **Stevens-Johnson Syndrome (SJS)**. * **Febuxostat:** A newer, non-purine selective inhibitor of XO used if allopurinol is not tolerated.

Question 115: Which antirheumatoid drug specifically acts on T-cells?

A. Etanercept
B. Infliximab
C. Rituximab
D. Abatacept (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. Abatacept** **Mechanism of Action:** Abatacept is a fusion protein (CTLA-4 linked to the Fc portion of IgG1) that acts as a **selective co-stimulation modulator**. For a T-cell to become fully activated, it requires two signals from an Antigen-Presenting Cell (APC). The second signal involves the binding of **CD80/86** on the APC to **CD28** on the T-cell. Abatacept binds to CD80/86 with high affinity, preventing it from interacting with CD28. This inhibits T-cell activation and the subsequent inflammatory cascade in Rheumatoid Arthritis. **Analysis of Incorrect Options:** * **A. Etanercept:** This is a soluble decoy receptor that binds to **TNF-α** and TNF-β, preventing them from interacting with cell surface receptors. It does not target T-cells directly. * **B. Infliximab:** This is a chimeric monoclonal antibody that binds directly to **TNF-α**. Like Etanercept, it is a TNF inhibitor, not a T-cell modulator. * **C. Rituximab:** This is a chimeric monoclonal antibody directed against the **CD20** antigen found on the surface of **B-lymphocytes**, leading to B-cell depletion. **High-Yield Clinical Pearls for NEET-PG:** * **Abatacept Mnemonic:** **A**batacept **A**nagonizes **A**PC-T cell interaction. * **Leflunomide:** Another T-cell related drug; it inhibits **dihydroorotate dehydrogenase**, leading to decreased pyrimidine synthesis and decreased T-cell proliferation. * **Anakinra:** An IL-1 receptor antagonist used in RA. * **Tocilizumab:** An IL-6 receptor antagonist. * **Screening:** Always screen for latent Tuberculosis (via Mantoux or IGRA) before starting any biological DMARD.

Question 116: Which of the following drugs used in gout acts by converting uric acid into allantoin?

A. Colchicine
B. Allopurinol
C. Probenecid
D. Rasburicase (Correct Answer)

Explanation: **Explanation:** **Correct Answer: D. Rasburicase** Rasburicase is a recombinant form of the enzyme **urate oxidase**. Humans lack this enzyme due to an evolutionary mutation. It works by catalyzing the oxidation of uric acid into **allantoin**, a highly water-soluble metabolite that is easily excreted by the kidneys. Because it works directly on existing uric acid in the blood, it acts rapidly and is primarily used to prevent and treat hyperuricemia in **Tumor Lysis Syndrome**. **Why other options are incorrect:** * **A. Colchicine:** It is an anti-inflammatory drug that inhibits **microtubule polymerization** by binding to tubulin. It prevents neutrophil migration and degranulation; it has no effect on uric acid levels. * **B. Allopurinol:** It is a hypuricemic agent that acts as a **xanthine oxidase inhibitor**. It prevents the *synthesis* of uric acid from hypoxanthine and xanthine but does not break down existing uric acid. * **C. Probenecid:** It is a **uricosuric** drug. It inhibits the URAT-1 transporter in the proximal tubule, thereby decreasing the reabsorption of uric acid and increasing its renal excretion. **High-Yield Clinical Pearls for NEET-PG:** * **Pegloticase:** A pegylated recombinant urate oxidase used for chronic refractory gout. * **Contraindication:** Rasburicase and Pegloticase are contraindicated in **G6PD deficiency** because the breakdown of uric acid produces hydrogen peroxide, which can trigger hemolysis. * **Drug of Choice:** Allopurinol is the DOC for chronic gout, while NSAIDs (or Colchicine) are the DOC for acute gouty attacks.

Question 117: Which drug has greater analgesic effects than morphine?

A. Heroin (Correct Answer)
B. Apomorphine
C. Codeine
D. Pethidine

Explanation: **Explanation:** The correct answer is **Heroin (Diacetylmorphine)**. The potency of an opioid analgesic is determined by its ability to cross the blood-brain barrier (BBB) and its affinity for mu-opioid receptors. Heroin is highly lipid-soluble due to the presence of two acetyl groups [2]. This allows it to cross the BBB much faster and in higher concentrations than morphine [1], [2]. Once in the brain, it is rapidly metabolized into 6-monoacetylmorphine and morphine, leading to a more intense and rapid analgesic effect (approximately 2–3 times more potent than morphine) [2]. **Analysis of Incorrect Options:** * **Apomorphine:** Despite its name, it is not an analgesic. It is a dopamine (D2) receptor agonist used primarily in Parkinson’s disease to treat "off" episodes and as an emetic in emergency toxicology. * **Codeine (Methylmorphine):** It is a much weaker analgesic (about 1/10th the potency of morphine). It acts as a prodrug that must be converted to morphine by the CYP2D6 enzyme to exert its effects [3]. * **Pethidine (Meperidine):** It is significantly less potent than morphine (about 1/10th). It has a shorter duration of action and possesses anticholinergic properties. **High-Yield Clinical Pearls for NEET-PG:** * **Potency Hierarchy:** Fentanyl (100x) > Heroin (2-3x) > Morphine (1x) > Pethidine (0.1x). * **Pethidine** is preferred in biliary colic because it causes less spasm of the Sphincter of Oddi compared to morphine. * **Heroin** is not used clinically in many countries (including India) due to its high addiction potential and "rush" effect [1], [2]. * **Pinpoint pupil (Miosis)** is a classic sign of opioid overdose, except with Pethidine (due to its atropine-like action).

Question 118: Which of the following are features of opioid withdrawal?

A. Constipation, bradycardia, coma
B. Abdominal cramps, vomiting, insomnia (Correct Answer)
C. Hyperthermia, vomiting, restlessness
D. Hypothermia, nausea, constipation

Explanation: Opioid withdrawal occurs due to the sudden cessation or reduction of opioid use in a physically dependent individual, or the administration of an opioid antagonist (e.g., Naloxone) [1]. The underlying mechanism is **rebound hyperactivity of the autonomic nervous system**, particularly the sympathetic system, as the body attempts to compensate for the absence of the chronic CNS depressant effect of opioids [1]. **Why Option B is Correct:** Opioids typically cause constipation, sedation, and miosis [3]. Withdrawal presents as the "polar opposite" of these effects: * **Gastrointestinal:** Increased motility leads to **abdominal cramps**, nausea, and **vomiting** [2]. * **CNS:** Hyper-excitability leads to **insomnia**, anxiety, and restlessness [2]. * **Autonomic:** Mydriasis, rhinorrhea, lacrimation, and piloerection ("cold turkey") [2]. **Why Other Options are Incorrect:** * **Option A & D:** Constipation and bradycardia are features of **opioid toxicity (overdose)**, not withdrawal [3]. In withdrawal, patients experience diarrhea and tachycardia [2]. * **Option C:** While vomiting and restlessness occur, **hyperthermia** is less characteristic than sweating and chills. Option B provides a more classic triad of withdrawal symptoms frequently tested in exams. **High-Yield Clinical Pearls for NEET-PG:** 1. **Objective Sign:** **Piloerection** (goosebumps) is a pathognomonic sign of severe opioid withdrawal [2]. 2. **Pupils:** Opioid overdose causes "pin-point pupils" (miosis), whereas withdrawal causes **mydriasis** (dilated pupils) [3]. 3. **Management:** * **Methadone or Buprenorphine** (Substitution therapy). * **Clonidine** (Alpha-2 agonist) is used to reduce sympathetic overactivity (tachycardia, hypertension). 4. **Severity:** While extremely distressing, opioid withdrawal is rarely life-threatening, unlike alcohol or benzodiazepine withdrawal (which can cause seizures).

Question 119: Which one of the following is the shortest acting intravenous analgesic?

A. Remifentanil (Correct Answer)
B. Fentanyl
C. Alfentanil
D. Sufentanil

Explanation: **Explanation:** The correct answer is **Remifentanil**. The primary factor determining the duration of action of these opioid analgesics is their metabolic pathway. Remifentanil is unique because it contains an **ester linkage**, making it susceptible to rapid hydrolysis by **non-specific plasma and tissue esterases**. Unlike other opioids, its metabolism is independent of hepatic or renal function. It has an ultra-short context-sensitive half-life (approximately 3–4 minutes) that remains constant regardless of the duration of infusion, allowing for rapid recovery. **Analysis of Incorrect Options:** * **Fentanyl:** A highly lipid-soluble opioid. While it has a rapid onset, its duration of action increases significantly with prolonged infusion due to redistribution and accumulation in adipose tissue (long context-sensitive half-life). * **Alfentanil:** Although it has a faster onset than fentanyl (due to a low pKa and high unionized fraction), its metabolism is hepatic (CYP3A4). It is shorter-acting than fentanyl but significantly longer-acting than remifentanil. * **Sufentanil:** The most potent opioid among the options. Like fentanyl, it is highly lipophilic and undergoes hepatic metabolism, resulting in a longer duration of action compared to remifentanil. **NEET-PG High-Yield Pearls:** * **Metabolism:** Remifentanil = Plasma esterases; Fentanyl/Alfentanil/Sufentanil = Hepatic (CYP450). * **Context-Sensitive Half-life:** This is the time required for the plasma concentration to decrease by 50% after stopping an infusion. Remifentanil has the shortest and most predictable context-sensitive half-life in clinical anesthesia. * **Clinical Use:** Remifentanil is ideal for procedures requiring intense analgesia with rapid emergence (e.g., neurosurgery or "total intravenous anesthesia" - TIVA).

Question 120: Which of the following opioid derivatives is a partial agonist as well as antagonist?

A. Buprenorphine
B. Naloxone
C. Nalorphine (Correct Answer)
D. Naltrexone

Explanation: The question tests the classification of opioid ligands based on their receptor activity. **Nalorphine** is a classic example of a **mixed agonist-antagonist** [2, 3]. It acts as a competitive antagonist at the $\mu$ (mu) receptors (blocking morphine-like effects) while simultaneously acting as a partial agonist at $\kappa$ (kappa) receptors (producing analgesia and sedation). Due to its $\mu$-antagonist properties, it can precipitate withdrawal symptoms in opioid-dependent individuals. **Analysis of Options:** * **Buprenorphine (Option A):** It is a **partial $\mu$-agonist** [1, 2, 3] and a $\kappa$-antagonist. It has a high affinity but low intrinsic activity at $\mu$ receptors, making it useful in opioid de-addiction [1]. * **Naloxone (Option B):** It is a **pure opioid antagonist** at $\mu$, $\kappa$, and $\delta$ receptors. It is the drug of choice for acute opioid poisoning due to its rapid onset (given IV). * **Naltrexone (Option D):** Similar to Naloxone, it is a **pure antagonist** but has a longer half-life and better oral bioavailability. It is primarily used for the maintenance of opioid-free states and alcohol dependence. **High-Yield Clinical Pearls for NEET-PG:** * **Pentazocine** is another mixed agonist-antagonist ($\kappa$ agonist, weak $\mu$ antagonist/partial agonist) [3]. * **Ceiling Effect:** Partial agonists and mixed agonist-antagonists exhibit a "ceiling effect" where increasing the dose beyond a point does not increase the respiratory depression or analgesia [1, 2]. * **Nalorphine** is rarely used clinically today because the $\kappa$-agonism causes unpleasant psychotomimetic effects (dysphoria, hallucinations).

Practice by Chapter

NSAIDs: Classification and Mechanism

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COX-2 Selective Inhibitors

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Acetaminophen (Paracetamol)

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Opioid Analgesics and Antagonists

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Drugs Used in Gout and Hyperuricemia

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Drugs Used in Rheumatoid Arthritis

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Disease-Modifying Antirheumatic Drugs

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Glucocorticoids as Anti-inflammatory Agents

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Migraine Therapeutics

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Neuropathic Pain Management

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