Analgesics and Anti-inflammatory Drugs — MCQs

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

Question 211: Buprenorphine on opioid receptors is:

A. Pure agonist
B. Pure antagonist
C. Partial agonist (Correct Answer)
D. None

Explanation: ### Explanation **Correct Answer: C. Partial agonist** **Mechanism of Action:** Buprenorphine is a semi-synthetic thebaine derivative with a unique pharmacological profile. It acts as a **partial agonist at the $\mu$ (mu) opioid receptors** and an **antagonist at the $\kappa$ (kappa) receptors**. As a partial agonist, it has a high affinity for the $\mu$ receptor but low intrinsic activity. This results in a "ceiling effect"—beyond a certain dose, increasing the amount of buprenorphine does not increase the analgesic effect or respiratory depression, making it safer than full agonists. **Analysis of Incorrect Options:** * **A. Pure agonist:** Drugs like **Morphine, Fentanyl, and Pethidine** are pure agonists. They have high intrinsic activity at $\mu$ receptors and do not exhibit a ceiling effect for analgesia or respiratory depression. * **B. Pure antagonist:** **Naloxone and Naltrexone** are pure antagonists. They bind to opioid receptors with high affinity but have zero intrinsic activity, used primarily to reverse opioid overdose. * **D. None:** Incorrect, as the pharmacological classification of Buprenorphine is well-established. **High-Yield Clinical Pearls for NEET-PG:** 1. **Ceiling Effect:** Buprenorphine is safer in overdose due to its ceiling effect on respiratory depression. 2. **Opioid Substitution Therapy:** Due to its long duration of action and slow dissociation from $\mu$ receptors, it is used in the management of **opioid dependence** (detoxification and maintenance). 3. **Precipitated Withdrawal:** If given to a patient physically dependent on a full agonist (like Morphine), Buprenorphine can displace the full agonist and precipitate withdrawal symptoms. 4. **Route:** It undergoes extensive first-pass metabolism; hence, it is administered **sublingually**, parenterally, or via transdermal patches.

Question 212: What is the mechanism of analgesia?

A. Nociceptin stimulation
B. Nocistatin stimulation
C. Anandamide receptors
D. Nicotinic and cholinergic receptors (Correct Answer)

Explanation: ### Explanation The mechanism of analgesia is multifaceted, involving various neurotransmitter systems. While opioids are the most common focus, the **cholinergic system** plays a critical role in modulating pain pathways. **Why Option D is Correct:** Nicotinic and muscarinic (cholinergic) receptors are found in high concentrations in the **dorsal horn of the spinal cord** and the **periaqueductal gray (PAG)**. * **Nicotinic Receptors:** Stimulation of nicotinic acetylcholine receptors (nAChRs), specifically the **α4β2 subtype**, triggers the release of endogenous opioids and inhibits the transmission of pain signals. * **Cholinergic Receptors:** Acetylcholine acts as an inhibitory neurotransmitter in the spinal cord. Drugs that increase cholinergic tone (like acetylcholinesterase inhibitors) or direct agonists (like Epibatidine) produce potent analgesic effects. **Analysis of Incorrect Options:** * **A. Nociceptin stimulation:** Nociceptin (Orphanin FQ) is an endogenous ligand for the NOP receptor. Unlike classical opioids, its stimulation often produces **pro-nociceptive** (pain-enhancing) effects or functional antagonism of opioid analgesia in certain parts of the brain. * **B. Nocistatin stimulation:** Nocistatin is a peptide derived from the same precursor as nociceptin, but it actually **blocks** nociceptin-induced pain. It does not produce analgesia on its own through "stimulation" in the classical sense. * **C. Anandamide receptors:** Anandamide is an endogenous cannabinoid that acts on **CB1 and CB2 receptors**. While it provides analgesia, the term "Anandamide receptors" is technically inaccurate; they are referred to as Cannabinoid receptors. **NEET-PG High-Yield Pearls:** * **Epibatidine:** A potent nicotinic agonist (derived from frog skin) that is 200 times more potent than morphine but too toxic for clinical use. * **Varenicline:** A partial agonist at α4β2 nicotinic receptors used for smoking cessation; it highlights the clinical application of nicotinic modulation. * **Nefopam:** A non-opioid analgesic that acts partly through modulating dopaminergic and cholinergic systems.

Question 213: What is true about febuxostat?

A. It is an anti-gout medication and a xanthine oxidase inhibitor. (Correct Answer)
B. It is a purine inhibitor.
C. Dose adjustment is required in renal impairment.
D. It has uricosuric action.

Explanation: **Explanation:** **1. Why Option A is Correct:** Febuxostat is a potent, **non-purine selective inhibitor of xanthine oxidase (XO)**. Xanthine oxidase is the enzyme responsible for converting hypoxanthine to xanthine and xanthine to uric acid. By inhibiting this enzyme, febuxostat effectively lowers serum uric acid levels, making it a first-line chronic management strategy for hyperuricemia in patients with gout. **2. Why the Other Options are Incorrect:** * **Option B:** Febuxostat is a **non-purine** inhibitor. Unlike Allopurinol (which is a purine analog), Febuxostat does not resemble a purine base. This structural difference allows it to be more selective for XO without interfering with other enzymes in the purine/pyrimidine metabolic pathway. * **Option C:** One of the major clinical advantages of Febuxostat is that it is primarily metabolized by the liver. Therefore, **no dose adjustment is required** in patients with mild-to-moderate renal impairment, unlike Allopurinol, which requires strict renal dosing. * **Option D:** Febuxostat is a **hypouricemic** (decreases production), not a uricosuric (which increases excretion via kidneys, like Probenecid or Lesinurad). **3. High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** It forms a stable complex with both the reduced and oxidized states of the XO enzyme. * **Efficacy:** It is more potent than Allopurinol at standard doses (80mg Febuxostat vs. 300mg Allopurinol). * **Black Box Warning:** The FDA has issued a warning regarding an increased risk of **cardiovascular death** associated with Febuxostat compared to Allopurinol; it should generally be reserved for patients who cannot tolerate Allopurinol. * **Acute Flare:** Like all urate-lowering therapies, it can precipitate an acute gouty attack upon initiation; co-administration with NSAIDs or Colchicine is recommended for the first few months.

Question 214: Which of the following is an ocular side-effect of HAART therapy?

A. Retinitis
B. Uveitis (Correct Answer)
C. Optic neuritis
D. Scleritis

Explanation: **Explanation:** The correct answer is **Uveitis**. This occurs primarily due to a phenomenon known as **Immune Recovery Uveitis (IRU)**, which is a specific manifestation of **Immune Reconstitution Inflammatory Syndrome (IRIS)**. When a patient with advanced HIV/AIDS starts Highly Active Antiretroviral Therapy (HAART), their CD4+ T-cell count rises rapidly. This restored immune system begins to mount an exaggerated inflammatory response against subclinical or pre-existing opportunistic infections in the eye (most commonly *Cytomegalovirus* or CMV). This results in intraocular inflammation, specifically **anterior uveitis or vitritis**, leading to symptoms like floaters and blurred vision. **Analysis of Incorrect Options:** * **A. Retinitis:** While CMV Retinitis is the most common ocular infection in AIDS patients (when CD4 <50), it is a manifestation of the **disease** itself, not a side effect of the HAART therapy. In fact, HAART helps resolve retinitis by restoring immunity. * **C. Optic Neuritis:** This is more commonly associated with drugs like **Ethambutol** (anti-TB) or conditions like Multiple Sclerosis, rather than standard HAART regimens. * **D. Scleritis:** This is typically associated with systemic autoimmune diseases (e.g., Rheumatoid Arthritis) and is not a recognized complication of HAART. **High-Yield Clinical Pearls for NEET-PG:** * **Cidofovir**, an antiviral used for CMV, is also a notorious pharmacological cause of drug-induced uveitis. * **Rifabutin** (often used in HIV patients for MAC prophylaxis) is another high-yield cause of drug-induced uveitis. * **IRIS** typically occurs when the CD4 count rises above 100 cells/µL following HAART initiation.

Question 215: Allopurinol specifically inhibits which enzyme?

A. Xanthine oxidase (Correct Answer)
B. Arginase
C. Carbamoyl transferase
D. Urease

Explanation: **Explanation:** **1. Why Xanthine Oxidase is correct:** Allopurinol is a structural analog of hypoxanthine. It acts as a **competitive inhibitor** of the enzyme **Xanthine Oxidase (XO)**. In the body, allopurinol is converted by XO into its active metabolite, **Alloxanthine (Oxypurinol)**, which then acts as a non-competitive inhibitor of the same enzyme (suicide inhibition). By inhibiting XO, allopurinol prevents the conversion of hypoxanthine to xanthine and xanthine to **uric acid**, thereby lowering serum urate levels. It is the drug of choice for the chronic management of gout. **2. Why other options are incorrect:** * **Arginase:** This enzyme is part of the Urea Cycle, responsible for converting Arginine into Urea and Ornithine. It is not involved in purine metabolism. * **Carbamoyl transferase:** Specifically, Ornithine Carbamoyltransferase (OCT) is another Urea Cycle enzyme. Deficiencies here lead to hyperammonemia, not hyperuricemia. * **Urease:** This enzyme catalyzes the hydrolysis of urea into ammonia and carbon dioxide. It is notably produced by *H. pylori* and certain urinary tract pathogens (e.g., *Proteus*), but it is not a target for allopurinol. **3. High-Yield Clinical Pearls for NEET-PG:** * **Hypersensitivity:** Allopurinol is associated with **HLA-B*5801**; testing is recommended in certain ethnicities to prevent Stevens-Johnson Syndrome (SJS). * **Drug Interactions:** Since XO metabolizes **6-Mercaptopurine (6-MP)** and **Azathioprine**, co-administration with Allopurinol leads to toxic levels of these drugs. Reduce their dose by 75%. * **Acute Gout:** Never start Allopurinol during an acute attack, as sudden fluctuations in urate levels can worsen the inflammation. * **Alternative:** **Febuxostat** is a newer, non-purine selective inhibitor of XO used in patients intolerant to allopurinol.

Question 216: Which of the following is NOT a rheumatoid disease modifying drug?

A. Chloroquine
B. Gold
C. Penicillamine
D. BAL (Correct Answer)

Explanation: **Explanation:** The correct answer is **BAL (British Anti-Lewisite)**. **1. Why BAL is the correct answer:** BAL, also known as **Dimercaprol**, is a **chelating agent**, not a Disease-Modifying Anti-Rheumatic Drug (DMARD). It is used primarily in the treatment of acute poisoning by heavy metals such as arsenic, mercury, and gold. It works by forming stable, non-toxic, soluble complexes with metal ions, which are then excreted in the urine. It has no role in modifying the autoimmune pathophysiology of Rheumatoid Arthritis (RA). **2. Why the other options are incorrect:** * **Chloroquine/Hydroxychloroquine:** These are **Antimalarials** used as "Conventional Synthetic DMARDs." They are preferred for mild RA or in combination therapy (Triple Therapy) due to their relatively low toxicity. * **Gold (Chrysotherapy):** Historically, gold salts (e.g., Sodium aurothiomalate) were mainstay DMARDs. They inhibit macrophage phagocytosis and lysosomal enzyme release. Though rarely used today due to toxicity, they are classified as DMARDs. * **Penicillamine:** This is a degradation product of penicillin that acts as a DMARD by reducing the numbers of T-lymphocytes and inhibiting collagen cross-linking. Like gold, its use has declined due to the availability of safer alternatives like Methotrexate. **3. High-Yield Clinical Pearls for NEET-PG:** * **DMARD of Choice:** Methotrexate is the "Gold Standard" and first-line DMARD for Rheumatoid Arthritis. * **BAL Contraindication:** It should not be used in **Iron or Cadmium poisoning** as the resulting complex is nephrotoxic. * **Ocular Toxicity:** Patients on Hydroxychloroquine require regular ophthalmological screening for **"Bull’s eye maculopathy."** * **Triple Therapy for RA:** Includes Methotrexate + Sulfasalazine + Hydroxychloroquine.

Question 217: All are TNF alpha inhibitors except?

A. Adalimumab
B. Bevacizumab (Correct Answer)
C. Infliximab
D. Etanercept

Explanation: **Explanation:** The question asks to identify the drug that is **not** a TNF-alpha (Tumor Necrosis Factor) inhibitor. **1. Why Bevacizumab is the correct answer:** **Bevacizumab** is a recombinant humanized monoclonal antibody that targets **VEGF (Vascular Endothelial Growth Factor)**, not TNF-alpha. By inhibiting VEGF, it prevents angiogenesis (the formation of new blood vessels). It is primarily used in oncology (e.g., colorectal cancer, renal cell carcinoma) and ophthalmology (e.g., wet macular degeneration). **2. Why the other options are incorrect (TNF-alpha Inhibitors):** * **Adalimumab (Option A):** A fully human monoclonal antibody that binds directly to TNF-alpha, preventing it from interacting with its receptors. * **Infliximab (Option C):** A chimeric (mouse-human) monoclonal antibody that binds to both soluble and transmembrane forms of TNF-alpha. * **Etanercept (Option D):** A soluble **fusion protein** (not a true monoclonal antibody) that acts as a "decoy receptor." It consists of the ligand-binding portion of the human TNF receptor linked to the Fc fraction of IgG1. **Clinical Pearls for NEET-PG:** * **Indications:** TNF inhibitors are used for Rheumatoid Arthritis, Psoriasis, Ankylosing Spondylitis, and IBD (Crohn’s/Ulcerative Colitis). * **Mandatory Screening:** Before starting TNF inhibitors, always screen for **Latent Tuberculosis (TB)** using a Mantoux test or IGRA, as these drugs can cause reactivation of TB. * **Other TNF Inhibitors:** Certolizumab and Golimumab. * **Suffix Mnemonic:** Drugs ending in **"-mab"** are Monoclonal Antibodies; **"-cept"** refers to a Receptor fusion protein.

Question 218: Anti-TNF alpha drugs are used for the treatment of all the following diseases EXCEPT:

A. Systemic lupus erythematosus (Correct Answer)
B. Seronegative arthritis
C. Psoriatic arthritis
D. Crohn's disease

Explanation: **Explanation:** Anti-TNF alpha agents (e.g., Infliximab, Adalimumab, Etanercept) are potent biological DMARDs that neutralize Tumor Necrosis Factor-alpha, a key pro-inflammatory cytokine. **Why Systemic Lupus Erythematosus (SLE) is the correct answer:** While TNF-alpha is involved in many autoimmune processes, anti-TNF drugs are generally **avoided in SLE**. In fact, these drugs are known to induce a "Lupus-like syndrome" (Drug-induced Lupus) characterized by the development of Anti-nuclear antibodies (ANA) and Anti-dsDNA antibodies. Using them in a patient with pre-existing SLE can exacerbate the disease or cause paradoxical flares. **Why the other options are incorrect:** * **Seronegative arthritis:** This group (including Ankylosing Spondylitis) is characterized by high TNF-alpha levels in the entheses and joints. Anti-TNF drugs are the gold standard for patients non-responsive to NSAIDs. * **Psoriatic arthritis:** TNF-alpha plays a central role in both skin plaque formation and joint destruction. These drugs are highly effective in treating both the cutaneous and articular manifestations. * **Crohn’s disease:** TNF-alpha is a primary driver of intestinal inflammation. Monoclonal antibodies like Infliximab are mainstay treatments for moderate-to-severe or fistulizing Crohn’s disease. **NEET-PG High-Yield Pearls:** 1. **Screening:** Always screen for **Latent Tuberculosis** (via TST or IGRA) and Hepatitis B before starting anti-TNF therapy, as these drugs can cause reactivation. 2. **Drug-Induced Lupus:** Among anti-TNF agents, **Infliximab** and **Etanercept** are most commonly associated with positive ANA titers. 3. **Contraindications:** Avoid anti-TNF drugs in patients with NYHA Class III/IV **Heart Failure** and demyelinating diseases like Multiple Sclerosis.

Question 219: Which of the following analgesic is used in arthritis and has a synovial fluid to plasma concentration ratio of 3:1?

A. Ibuprofen
B. Diclofenac (Correct Answer)
C. Tenoxicam
D. Piroxicam

Explanation: **Explanation:** **Diclofenac** is the correct answer due to its unique pharmacokinetic profile. While most NSAIDs have high plasma protein binding, Diclofenac exhibits a significant "preferential accumulation" in the synovial fluid. Although its plasma half-life is short (approx. 1–2 hours), it persists in the synovial fluid for much longer. The **synovial fluid to plasma concentration ratio is approximately 3:1**, making it exceptionally effective for chronic joint conditions like osteoarthritis and rheumatoid arthritis, as it provides prolonged local therapeutic effects despite low systemic levels. **Analysis of Incorrect Options:** * **Ibuprofen (A):** It has a short half-life (2 hours) and penetrates the synovial fluid, but it does not achieve the 3:1 concentration ratio seen with Diclofenac. Its concentrations in the joint are generally lower than or equal to plasma levels. * **Tenoxicam (C) & Piroxicam (D):** These are oxicam derivatives characterized by very **long plasma half-lives** (approx. 50–70 hours). While they are used in arthritis, they do not show the specific 3:1 synovial-to-plasma ratio; rather, they maintain steady-state concentrations in both compartments due to their slow elimination. **High-Yield NEET-PG Pearls:** * **Mechanism:** Diclofenac is a non-selective COX inhibitor but also slightly inhibits the lipoxygenase (LOX) pathway and reduces intracellular arachidonic acid concentrations. * **Toxicity:** Diclofenac is associated with a higher risk of **hepatotoxicity** compared to other NSAIDs. * **Formulations:** It is often combined with Misoprostol (a PGE1 analog) to prevent NSAID-induced peptic ulcers. * **Topical Advantage:** Due to its high potency and tissue penetration, it is the most commonly used topical NSAID gel.

Question 220: A 24-year-old female presents with severe pain during menses (dysmenorrhea). To treat her symptoms, you advise her to take indomethacin in the hope that it will reduce her pain by interfering with the production of which substance?

A. Bradykinin
B. Histamine
C. Leukotrienes
D. Prostaglandin F2 (Correct Answer)

Explanation: **Explanation:** **1. Why Prostaglandin F2α is Correct:** Primary dysmenorrhea is caused by the excessive production of endometrial prostaglandins, specifically **Prostaglandin F2α (PGF2α)** and PGE2, during menstruation. PGF2α is a potent stimulator of myometrial contractions and a vasoconstrictor. High levels lead to uterine hypercontractility and ischemia, which manifest as cramping pain. **Indomethacin**, a non-selective Non-Steroidal Anti-inflammatory Drug (NSAID), acts by inhibiting the enzyme **Cyclooxygenase (COX)**. This inhibition prevents the conversion of arachidonic acid into prostaglandins, thereby reducing uterine pressure and relieving pain. **2. Why Other Options are Incorrect:** * **A. Bradykinin:** While bradykinin is a potent pain mediator involved in acute inflammation and vasodilation, it is not the primary driver of menstrual uterine contractions. * **B. Histamine:** Histamine is primarily involved in allergic reactions and gastric acid secretion; it does not play a significant role in the pathogenesis of dysmenorrhea. * **C. Leukotrienes:** These are products of the **Lipoxygenase (LOX)** pathway. While they may contribute to some inflammatory processes, NSAIDs like indomethacin do not inhibit their production; in fact, COX inhibition can sometimes "shunt" arachidonic acid toward the LOX pathway. **3. NEET-PG High-Yield Pearls:** * **Drug of Choice:** NSAIDs (like Mefenamic acid or Ibuprofen) are the first-line treatment for primary dysmenorrhea. * **Mechanism:** NSAIDs are most effective if started 1–2 days before the onset of menses or at the earliest sign of pain. * **Indomethacin Specifics:** Apart from dysmenorrhea, it is the drug of choice for **Ankylosing Spondylitis**, **Bartter syndrome**, and promoting the **closure of Patent Ductus Arteriosus (PDA)** in neonates.

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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