Pharmacology MCQs — Part 1 (Q1–Q25)

Q1. The fraction of an administered dose that reaches the systemic circulation unchanged is called:

A. Clearance
B. Bioavailability ✅
C. Volume of distribution
D. Half-life

A: Clearance is the volume of plasma cleared of drug per unit time, not the fraction absorbed.
B: Bioavailability (F) is the fraction of unchanged drug that reaches systemic blood; IV dosing has F = 1.
C: Vd relates the amount of drug in the body to plasma concentration; not about absorption fraction.
D: Half-life is the time for plasma concentration to fall by 50%; unrelated to absorption fraction.

Q2. A drug exhibits first-order elimination. Which is true?

A. A constant amount is eliminated per unit time
B. A constant fraction is eliminated per unit time ✅
C. Elimination is saturable at therapeutic doses
D. Half-life changes with dose

A: Constant amount/time describes zero-order elimination.
B: First-order elimination removes a fixed proportion per unit time; rate ∝ concentration.
C: Saturation at therapeutic range suggests zero-order or capacity-limited kinetics.
D: For first-order, half-life is constant and independent of dose.

Q3. Which route avoids first-pass metabolism most completely?

A. Intravenous ✅
B. Oral
C. Sublingual
D. Rectal

A: IV delivers drug directly to systemic circulation; no first pass.
B: Oral drugs enter portal circulation and undergo first-pass hepatic metabolism.
C: Sublingual largely avoids first pass but not as absolute as IV.
D: Rectal partly avoids first pass; some drains to portal vein.

Q4. Competitive antagonists typically:

A. Reduce maximal efficacy (Emax)
B. Shift the agonist dose–response curve right (↑EC50) without changing Emax ✅
C. Shift curve left (↓EC50) and ↑Emax
D. Produce irreversible receptor inactivation

A: Noncompetitive antagonists reduce Emax.
B: Competitive antagonism increases EC50 (less potency) but Emax is preserved with enough agonist.
C: Left shift indicates higher potency, not expected with antagonism.
D: Irreversible binding is characteristic of noncompetitive/insurmountable antagonists.

Q5. Volume of distribution (Vd) is high when a drug is:

A. Highly lipophilic and tissue-bound ✅
B. Highly protein bound in plasma
C. Confined to extracellular fluid only
D. Ionized and hydrophilic

A: Lipophilic, tissue-sequestered drugs distribute widely → large Vd.
B: Plasma protein binding keeps drug intravascular → low Vd.
C: Restriction to ECF yields moderate Vd.
D: Ionized/hydrophilic drugs remain in plasma/ECF → smaller Vd.

Q6. Which enzyme is central to Phase I oxidation of many drugs?

A. Alcohol dehydrogenase
B. Cytochrome P450 (CYP) monooxygenase ✅
C. UDP-glucuronyl transferase
D. N-acetyltransferase

A: ADH handles ethanol; not the general oxidizer of xenobiotics.
B: CYPs catalyze Phase I oxidations, increasing polarity.
C: UGT is Phase II conjugation (glucuronidation).
D: NAT is Phase II acetylation.

Q7. A partial agonist at a receptor will:

A. Produce full efficacy at high doses
B. Reduce response to a full agonist (functional antagonism) ✅
C. Have zero intrinsic activity
D. Increase Emax in presence of antagonist

A: Partial agonists never reach full Emax even at high concentration.
B: By occupying receptors with lower intrinsic activity, they blunt full agonist response.
C: Zero intrinsic activity defines a pure antagonist, not partial agonist.
D: They decrease combined Emax vs full agonist alone.

Q8. Drug A (weak acid) is trapped in alkaline urine. This is an example of:

A. Active tubular secretion
B. Ion trapping via urinary alkalinization ✅
C. Zero-order elimination
D. Enterohepatic recycling

A: Active secretion is transporter-mediated, not pH dependent in this way.
B: Alkaline urine ionizes weak acids → ↓reabsorption → ↑excretion.
C: Kinetics type is unrelated to pH trapping.
D: Recycling returns drug to intestine via bile, not urine pH.

Q9. The therapeutic index (TI) is typically defined as:

A. LD50/ED10
B. TD50/ED50 (or LD50/ED50 in animals) ✅
C. ED50/TD50
D. EC50/IC50

A: Not standard; ED10 uncommon in TI.
B: TI compares toxic dose to effective dose—higher is safer.
C: Inverse of standard TI.
D: EC/IC50 relate to potency in vitro, not safety margin.

Q10. A drug shows rapid tolerance after repeated dosing due to receptor down-regulation. This is:

A. Tachyphylaxis
B. Pharmacodynamic tolerance ✅
C. Pharmacokinetic tolerance
D. Placebo effect

A: Tachyphylaxis is very acute tolerance after few doses, often via transmitter depletion.
B: Receptor down-regulation decreases response at same concentration—PD tolerance.
C: PK tolerance is increased metabolism/clearance.
D: Placebo is response from expectation, not tolerance.

Q11. Which β-blocker has additional α1-blocking leading to vasodilation?

A. Metoprolol
B. Carvedilol ✅
C. Atenolol
D. Esmolol

A: Metoprolol is β1-selective without α1 block.
B: Carvedilol blocks β1/β2 and α1 → ↓afterload.
C: Atenolol is β1-selective.
D: Esmolol is ultra-short-acting β1-selective IV agent.

Q12. Atropine will most reliably:

A. Induce miosis
B. Increase heart rate by blocking M2 receptors ✅
C. Stimulate sweating
D. Increase GI motility

A: Atropine causes mydriasis (not miosis).
B: Muscarinic blockade in SA node removes vagal tone → tachycardia.
C: Sweat glands are sympathetic cholinergic; atropine blocks sweating → dry skin.
D: It decreases GI motility → constipation.

Q13. Which drug inhibits acetylcholinesterase irreversibly?

A. Organophosphates (e.g., parathion) ✅
B. Neostigmine
C. Edrophonium
D. Physostigmine

A: Organophosphates phosphorylate AChE; “aging” makes inhibition persistent.
B: Neostigmine is reversible carbamate inhibitor.
C: Edrophonium is short-acting reversible AChE inhibitor.
D: Physostigmine is reversible and crosses BBB.

Q14. A selective α2-agonist used for hypertension and ADHD:

A. Phenylephrine
B. Clonidine ✅
C. Dobutamine
D. Albuterol

A: Phenylephrine is α1-agonist (vasoconstriction).
B: Clonidine stimulates central α2 → ↓sympathetic outflow.
C: Dobutamine is β1-agonist (inotropy).
D: Albuterol is β2-agonist (bronchodilation).

Q15. Which calcium channel blocker is most cardio-selective (rate control)?

A. Nifedipine
B. Verapamil ✅
C. Amlodipine
D. Nicardipine

A: Dihydropyridine; vascular selective → reflex tachycardia.
B: Verapamil (non-DHP) depresses AV conduction → rate control.
C: Dihydropyridine; long-acting vasodilator.
D: DHP with cerebrovascular preference.

Q16. ACE inhibitors decrease blood pressure mainly by:

A. Increasing aldosterone
B. Decreasing angiotensin II and increasing bradykinin ✅
C. Blocking β1 receptors
D. Direct arterial dilation via NO release

A: Aldosterone falls with ACE inhibition.
B: Less Ang II → vasodilation; ↑bradykinin contributes to vasodilation and cough.
C: β1 block is unrelated to ACE inhibitors.
D: NO effect is not their primary mechanism.

Q17. Which diuretic can cause ototoxicity, especially with aminoglycosides?

A. Hydrochlorothiazide
B. Furosemide ✅
C. Spironolactone
D. Acetazolamide

A: Thiazides rarely cause ototoxicity.
B: Loop diuretics (e.g., furosemide) can be ototoxic at high doses/IV.
C: Spironolactone causes endocrine effects (gynecomastia, hyperkalemia).
D: Acetazolamide causes metabolic acidosis, paresthesias.

Q18. Which statin is most potent at lowering LDL-C?

A. Pravastatin
B. Rosuvastatin ✅
C. Fluvastatin
D. Lovastatin

A: Moderate potency.
B: Rosuvastatin (and atorvastatin) are high-intensity options with strong LDL reduction.
C: Lower potency.
D: Moderate potency, prodrug.

Q19. A patient on isoniazid develops peripheral neuropathy. Which vitamin prevents this?

A. Vitamin B12
B. Vitamin B2
C. Vitamin B6 (pyridoxine) ✅
D. Vitamin B1

A: B12 treats macrocytic anemia/neurologic deficits, not INH neuropathy.
B: B2 deficiency causes cheilosis, corneal vascularization.
C: INH depletes pyridoxine → neuropathy; supplementation prevents it.
D: B1 deficiency leads to beriberi/Wernicke’s.

Q20. Which antibiotic inhibits bacterial peptidoglycan cross-linking by binding PBPs?

A. Penicillins ✅
B. Vancomycin
C. Daptomycin
D. Azithromycin

A: β-lactams bind transpeptidases (PBPs) → block cross-linking.
B: Vancomycin binds D-Ala-D-Ala, blocking polymerization (different target).
C: Daptomycin disrupts Gram-positive cell membranes.
D: Macrolides inhibit 50S ribosomal translocation.

Q21. A “disulfiram-like” reaction is classically associated with:

A. Azithromycin
B. Metronidazole ✅
C. Ciprofloxacin
D. Gentamicin

A: Macrolides do not cause disulfiram-like reactions.
B: Metronidazole + alcohol → flushing, tachycardia, nausea.
C: Quinolones risk tendinopathy, QT prolongation.
D: Aminoglycosides cause nephro/ototoxicity.

Q22. Which antifungal inhibits 14-α-demethylase (ergosterol synthesis)?

A. Amphotericin B
B. Fluconazole ✅
C. Caspofungin
D. Terbinafine

A: Amphotericin binds ergosterol and forms pores.
B: Azoles inhibit fungal CYP450 14-α-demethylase → ↓ergosterol.
C: Echinocandins inhibit β-glucan synthesis in cell wall.
D: Terbinafine inhibits squalene epoxidase.

Q23. Which insulin is ultra-rapid acting?

A. NPH
B. Lispro ✅
C. Glargine
D. Regular insulin

A: NPH is intermediate-acting.
B: Lispro (also aspart, glulisine) has rapid onset/short duration for meals.
C: Glargine is long-acting, peakless.
D: Regular is short-acting, slower than lispro.

Q24. A selective COX-2 inhibitor with lower GI ulcer risk is:

A. Aspirin
B. Ibuprofen
C. Celecoxib ✅
D. Indomethacin

A: Aspirin irreversibly inhibits COX-1/2 and increases GI risk.
B: Ibuprofen is nonselective COX inhibitor.
C: Celecoxib spares COX-1 → less GI toxicity but ↑CV risk.
D: Indomethacin is nonselective with notable GI/CNS effects.

Q25. Naloxone reverses opioid overdose by:

A. Partial agonism at μ receptors
B. Competitive antagonism at opioid receptors ✅
C. Inhibiting opioid metabolism
D. Enhancing GABA release

A: Partial agonists (buprenorphine) can precipitate withdrawal but still activate μ.
B: Naloxone is a high-affinity competitive antagonist at μ (also κ, δ) reversing respiratory depression.
C: It doesn’t affect metabolism; it displaces opioids from receptors.
D: Mechanism is receptor blockade, not GABA modulation.

Pharmacology MCQs — Part 2 (Q26–Q50)

Q26. Which of the following is a selective β2-adrenergic agonist used for asthma?

A. Propranolol
B. Dobutamine
C. Salbutamol (Albuterol) ✅
D. Phenylephrine

A: Propranolol is a nonselective β-blocker; contraindicated in asthma.
B: Dobutamine is β1-agonist used in acute heart failure.
C: Salbutamol selectively stimulates β2 → bronchodilation.
D: Phenylephrine is α1-agonist → vasoconstriction, not bronchodilation.

Q27. Which opioid analgesic also has NMDA antagonist activity, reducing tolerance?

A. Morphine
B. Fentanyl
C. Methadone ✅
D. Codeine

A: Morphine acts on μ receptors but no NMDA block.
B: Fentanyl is a potent μ-agonist without NMDA effect.
C: Methadone is μ-agonist + NMDA antagonist → useful in neuropathic pain and addiction therapy.
D: Codeine is weaker opioid, mainly μ receptor action.

Q28. Which drug is first-line in acute status epilepticus?

A. Phenytoin
B. Lorazepam (IV benzodiazepine) ✅
C. Carbamazepine
D. Ethosuximide

A: Phenytoin is used for maintenance, not initial management.
B: IV benzodiazepines (lorazepam/diazepam) are first-line to stop seizures quickly.
C: Carbamazepine treats focal and tonic-clonic seizures, not emergencies.
D: Ethosuximide treats absence seizures, not status epilepticus.

Q29. A patient taking lithium is at greatest risk for toxicity if also prescribed:

A. Thiazide diuretics ✅
B. Loop diuretics
C. Calcium channel blockers
D. Proton pump inhibitors

A: Thiazides decrease renal clearance of lithium → toxicity.
B: Loops have less effect than thiazides.
C: CCBs don’t strongly affect lithium clearance.
D: PPIs do not significantly alter lithium levels.

Q30. Which antipsychotic has the highest risk of agranulocytosis?

A. Risperidone
B. Olanzapine
C. Haloperidol
D. Clozapine ✅

A: Risperidone → hyperprolactinemia, EPS risk.
B: Olanzapine → weight gain, metabolic syndrome.
C: Haloperidol → EPS, NMS, QT prolongation.
D: Clozapine carries risk of agranulocytosis; requires blood monitoring.

Q31. Flumazenil is an antagonist at which receptor?

A. GABA-A chloride channel
B. GABA-B receptor
C. Benzodiazepine binding site on GABA-A receptor ✅
D. NMDA receptor

A: GABA-A is the ion channel, but flumazenil doesn’t block GABA itself.
B: GABA-B is a GPCR targeted by baclofen.
C: Flumazenil competitively inhibits benzodiazepine binding site → reverses overdose.
D: NMDA receptors are for glutamate; not related.

Q32. Which antiarrhythmic drug is a potassium channel blocker (Class III)?

A. Verapamil
B. Lidocaine
C. Amiodarone ✅
D. Quinidine

A: Verapamil is Class IV (calcium channel blocker).
B: Lidocaine is Class Ib (Na+ channel blocker).
C: Amiodarone blocks K+ channels → prolongs repolarization (APD, QT).
D: Quinidine is Class Ia (Na+ channel blocker).

Q33. Which antitubercular drug causes orange-red discoloration of body fluids?

A. Isoniazid
B. Ethambutol
C. Rifampicin ✅
D. Pyrazinamide

A: INH → hepatotoxicity, neuropathy.
B: Ethambutol → optic neuritis (red-green blindness).
C: Rifampicin colors urine, tears, sweat orange-red.
D: Pyrazinamide → hyperuricemia, hepatotoxicity.

Q34. Which proton pump inhibitor is commonly used for peptic ulcer disease?

A. Ranitidine
B. Omeprazole ✅
C. Misoprostol
D. Sucralfate

A: Ranitidine is an H2 blocker.
B: Omeprazole irreversibly inhibits H+/K+-ATPase → strong acid suppression.
C: Misoprostol is PGE1 analog, used in NSAID-induced ulcers.
D: Sucralfate forms protective mucosal coating.

Q35. Which drug is used for medical abortion along with misoprostol?

A. Mifepristone ✅
B. Clomiphene
C. Tamoxifen
D. Oxytocin

A: Mifepristone is a progesterone receptor antagonist → detaches embryo. Misoprostol induces uterine contraction.
B: Clomiphene stimulates ovulation in infertility.
C: Tamoxifen is SERM used in breast cancer.
D: Oxytocin is used for induction of labor, not early abortion.

Q36. A selective estrogen receptor modulator (SERM) used in breast cancer:

A. Finasteride
B. Tamoxifen ✅
C. Flutamide
D. Mifepristone

A: Finasteride is 5α-reductase inhibitor.
B: Tamoxifen antagonizes estrogen receptors in breast but agonist in bone/uterus.
C: Flutamide is androgen receptor antagonist.
D: Mifepristone is a progesterone antagonist.

Q37. Which antiplatelet drug irreversibly inhibits COX-1 in platelets?

A. Clopidogrel
B. Ticagrelor
C. Aspirin ✅
D. Abciximab

A: Clopidogrel blocks ADP receptor (P2Y12).
B: Ticagrelor is a reversible P2Y12 inhibitor.
C: Aspirin acetylates COX-1 irreversibly → ↓TXA2 → less platelet aggregation.
D: Abciximab blocks GPIIb/IIIa receptor.

Q38. Which anticoagulant enhances antithrombin III activity?

A. Warfarin
B. Heparin ✅
C. Rivaroxaban
D. Dabigatran

A: Warfarin inhibits vitamin K epoxide reductase → ↓clotting factor synthesis.
B: Heparin accelerates antithrombin → inactivates thrombin and Xa.
C: Rivaroxaban directly inhibits Xa.
D: Dabigatran directly inhibits thrombin.

Q39. A selective serotonin reuptake inhibitor (SSRI) is:

A. Amitriptyline
B. Venlafaxine
C. Fluoxetine ✅
D. Phenelzine

A: Amitriptyline is TCA.
B: Venlafaxine is SNRI.
C: Fluoxetine is SSRI → 1st line for depression, anxiety.
D: Phenelzine is MAOI.

Q40. Which antidiabetic drug activates PPAR-γ to increase insulin sensitivity?

A. Metformin
B. Pioglitazone ✅
C. Acarbose
D. Glibenclamide

A: Metformin ↓hepatic gluconeogenesis, ↑insulin sensitivity (AMPK activation).
B: Pioglitazone (thiazolidinedione) activates PPAR-γ nuclear receptor.
C: Acarbose inhibits α-glucosidase in intestine.
D: Glibenclamide is sulfonylurea → stimulates insulin release.

Q41. Which drug is a dopamine precursor used in Parkinson’s disease?

A. Selegiline
B. Levodopa ✅
C. Bromocriptine
D. Benztropine

A: Selegiline inhibits MAO-B → prevents dopamine breakdown.
B: Levodopa is converted to dopamine in CNS.
C: Bromocriptine is D2 agonist.
D: Benztropine is anticholinergic for tremor/rigidity.

Q42. Which drug is a long-acting muscarinic antagonist used in COPD?

A. Salmeterol
B. Tiotropium ✅
C. Montelukast
D. Theophylline

A: Salmeterol is long-acting β2-agonist.
B: Tiotropium blocks M3 receptors in airway smooth muscle → bronchodilation.
C: Montelukast is leukotriene receptor antagonist.
D: Theophylline inhibits PDE → ↑cAMP, bronchodilation.

Q43. Which local anesthetic has the shortest duration of action?

A. Lidocaine
B. Bupivacaine
C. Procaine ✅
D. Ropivacaine

A: Lidocaine is intermediate-acting.
B: Bupivacaine is long-acting, more cardiotoxic.
C: Procaine (ester type) is short-acting.
D: Ropivacaine is long-acting, less cardiotoxic.

Q44. A selective α1-blocker used for benign prostatic hyperplasia (BPH):

A. Clonidine
B. Propranolol
C. Tamsulosin ✅
D. Atenolol

A: Clonidine is α2-agonist.
B: Propranolol is nonselective β-blocker.
C: Tamsulosin relaxes prostatic smooth muscle via α1A blockade.
D: Atenolol is β1-blocker.

Q45. Which chemotherapy agent causes hemorrhagic cystitis?

A. Methotrexate
B. Vincristine
C. Cyclophosphamide ✅
D. Cisplatin

A: Methotrexate → myelosuppression, hepatotoxicity.
B: Vincristine → neurotoxicity.
C: Cyclophosphamide → metabolite acrolein causes cystitis (prevented by mesna).
D: Cisplatin → nephrotoxicity, ototoxicity.

Q46. Which monoclonal antibody targets HER2/neu in breast cancer?

A. Rituximab
B. Bevacizumab
C. Trastuzumab ✅
D. Cetuximab

A: Rituximab → CD20 (B-cell lymphomas).
B: Bevacizumab → VEGF.
C: Trastuzumab → HER2 receptor, breast/gastric cancers.
D: Cetuximab → EGFR.

Q47. Which antimalarial is associated with vivid dreams and neuropsychiatric effects?

A. Chloroquine
B. Mefloquine ✅
C. Artemisinin
D. Primaquine

A: Chloroquine → retinopathy, pruritus.
B: Mefloquine causes nightmares, psychosis.
C: Artemisinin → neurotoxicity rare, safe in pregnancy.
D: Primaquine → hemolysis in G6PD deficiency.

Q48. Which drug inhibits dihydrofolate reductase in bacteria?

A. Sulfonamides
B. Trimethoprim ✅
C. Ciprofloxacin
D. Rifampicin

A: Sulfonamides inhibit dihydropteroate synthase.
B: Trimethoprim blocks DHFR → ↓THF synthesis.
C: Ciprofloxacin inhibits DNA gyrase/topoisomerase.
D: Rifampicin inhibits RNA polymerase.

Q49. Which anti-HIV drug is a non-nucleoside reverse transcriptase inhibitor (NNRTI)?

A. Zidovudine
B. Tenofovir
C. Efavirenz ✅
D. Ritonavir

A: Zidovudine is NRTI.
B: Tenofovir is NRTI (nucleotide analog).
C: Efavirenz is NNRTI → directly binds reverse transcriptase.
D: Ritonavir is protease inhibitor.

Q50. Which chemotherapeutic drug is a topoisomerase II inhibitor?

A. Methotrexate
B. Etoposide ✅
C. Paclitaxel
D. Bleomycin

A: Methotrexate → folate antagonist.
B: Etoposide inhibits topoisomerase II → DNA breaks.
C: Paclitaxel stabilizes microtubules.
D: Bleomycin causes DNA strand breaks via free radicals.

Pharmacology MCQs — Part 3 (Q51–Q75)

Q51. Which drug is most effective for motion sickness?

A. Metoclopramide
B. Scopolamine ✅
C. Ondansetron
D. Domperidone

A: Metoclopramide is D2 antagonist, used for chemotherapy-induced vomiting.
B: Scopolamine (antimuscarinic) is very effective for motion sickness.
C: Ondansetron is 5-HT3 antagonist, used in postoperative and chemotherapy vomiting.
D: Domperidone is a peripheral D2 antagonist, not first-line for motion sickness.

Q52. Which antiemetic is a 5-HT3 antagonist?

A. Metoclopramide
B. Chlorpromazine
C. Ondansetron ✅
D. Diphenhydramine

A: Metoclopramide is D2 antagonist.
B: Chlorpromazine blocks D2, H1, muscarinic receptors.
C: Ondansetron blocks 5-HT3 receptors in gut and brain → excellent antiemetic for chemo.
D: Diphenhydramine is H1 blocker, used for motion sickness.

Q53. Which is the antidote for benzodiazepine overdose?

A. Flumazenil ✅
B. Naloxone
C. Atropine
D. Protamine sulfate

A: Flumazenil is a benzodiazepine site antagonist at GABA-A receptor.
B: Naloxone reverses opioid toxicity.
C: Atropine is antidote for organophosphate poisoning.
D: Protamine sulfate reverses heparin.

Q54. Which anti-helminthic drug works by inhibiting microtubule synthesis?

A. Praziquantel
B. Albendazole ✅
C. Ivermectin
D. Niclosamide

A: Praziquantel increases Ca²⁺ permeability in trematodes/cestodes.
B: Albendazole binds β-tubulin, inhibits microtubule polymerization → effective against nematodes.
C: Ivermectin increases GABA-mediated chloride influx in nematodes.
D: Niclosamide uncouples oxidative phosphorylation in tapeworms.

Q55. Which antibiotic can cause “Gray baby syndrome”?

A. Chloramphenicol ✅
B. Erythromycin
C. Gentamicin
D. Vancomycin

A: Chloramphenicol causes gray baby syndrome due to immature UDP-glucuronyl transferase in neonates.
B: Erythromycin → diarrhea, QT prolongation.
C: Gentamicin → ototoxicity, nephrotoxicity.
D: Vancomycin → Red man syndrome.

Q56. Which drug is used in prophylaxis of malaria for travelers?

A. Mefloquine ✅
B. Artemisinin
C. Quinine
D. Chloroquine (in resistant areas)

A: Mefloquine is often given for prophylaxis in chloroquine-resistant regions.
B: Artemisinin is used for treatment, not prophylaxis.
C: Quinine is used in severe malaria.
D: Chloroquine works only in non-resistant regions.

Q57. Which drug is used to prevent chemotherapy-induced neutropenia?

A. Filgrastim (G-CSF) ✅
B. Erythropoietin
C. Interferon-alpha
D. Aldesleukin

A: Filgrastim stimulates granulocyte production → prevents neutropenia.
B: Erythropoietin stimulates RBC production.
C: Interferon-alpha has antiviral, anticancer activity.
D: Aldesleukin is IL-2 analog for renal cell carcinoma, melanoma.

Q58. Which β-lactamase inhibitor is combined with amoxicillin?

A. Sulbactam
B. Clavulanic acid ✅
C. Tazobactam
D. Avibactam

A: Sulbactam is combined with ampicillin.
B: Amoxicillin + clavulanic acid = Augmentin.
C: Tazobactam is often used with piperacillin.
D: Avibactam is a newer inhibitor.

Q59. Which drug inhibits viral neuraminidase?

A. Zidovudine
B. Acyclovir
C. Oseltamivir ✅
D. Ribavirin

A: Zidovudine is NRTI.
B: Acyclovir inhibits viral DNA polymerase (HSV, VZV).
C: Oseltamivir inhibits neuraminidase → prevents influenza virus release.
D: Ribavirin interferes with viral RNA synthesis.

Q60. Which anti-cancer drug inhibits dihydrofolate reductase?

A. 5-Fluorouracil
B. Methotrexate ✅
C. Cyclophosphamide
D. Dactinomycin

A: 5-FU inhibits thymidylate synthase.
B: Methotrexate blocks DHFR → ↓dTMP synthesis.
C: Cyclophosphamide alkylates DNA.
D: Dactinomycin intercalates DNA.

Q61. Which antidiabetic drug causes lactic acidosis rarely?

A. Glibenclamide
B. Metformin ✅
C. Pioglitazone
D. Acarbose

A: Sulfonylureas → hypoglycemia.
B: Metformin rarely causes lactic acidosis, especially in renal impairment.
C: Pioglitazone → weight gain, fluid retention.
D: Acarbose → flatulence, diarrhea.

Q62. Which antithyroid drug is safe in the first trimester of pregnancy?

A. Propylthiouracil (PTU) ✅
B. Methimazole
C. Levothyroxine
D. Radioactive iodine

A: PTU is preferred in first trimester due to less teratogenicity.
B: Methimazole can cause aplasia cutis in fetus.
C: Levothyroxine is replacement therapy for hypothyroidism, not antithyroid.
D: Radioactive iodine is contraindicated in pregnancy.

Q63. Which drug is a dopamine D2 antagonist used as an antiemetic?

A. Ondansetron
B. Metoclopramide ✅
C. Domperidone
D. Lorazepam

A: Ondansetron is 5-HT3 antagonist.
B: Metoclopramide blocks D2 receptors in CTZ → antiemetic.
C: Domperidone is peripheral D2 antagonist with less CNS effect.
D: Lorazepam is anxiolytic, not standard antiemetic.

Q64. Which antiretroviral drug causes hyperbilirubinemia and kidney stones?

A. Zidovudine
B. Efavirenz
C. Indinavir ✅
D. Nevirapine

A: Zidovudine → anemia.
B: Efavirenz → vivid dreams, CNS toxicity.
C: Indinavir (protease inhibitor) causes nephrolithiasis, indirect hyperbilirubinemia.
D: Nevirapine → hepatotoxicity, rash.

Q65. Which immunosuppressant inhibits calcineurin by binding FKBP-12?

A. Cyclosporine
B. Tacrolimus ✅
C. Sirolimus
D. Azathioprine

A: Cyclosporine binds cyclophilin, not FKBP.
B: Tacrolimus binds FKBP-12 → inhibits calcineurin → ↓IL-2.
C: Sirolimus also binds FKBP but inhibits mTOR, not calcineurin.
D: Azathioprine is purine analog → blocks DNA synthesis.

Q66. Which drug is a leukotriene receptor antagonist used in asthma?

A. Theophylline
B. Montelukast ✅
C. Cromolyn sodium
D. Salbutamol

A: Theophylline inhibits PDE → bronchodilation.
B: Montelukast blocks leukotriene D4 receptor (LTD4) → ↓bronchoconstriction.
C: Cromolyn stabilizes mast cells → prevents histamine release.
D: Salbutamol is β2 agonist.

Q67. Which drug inhibits xanthine oxidase, preventing uric acid synthesis?

A. Probenecid
B. Allopurinol ✅
C. Colchicine
D. Febuxostat

A: Probenecid increases uric acid excretion.
B: Allopurinol inhibits xanthine oxidase → ↓uric acid.
C: Colchicine inhibits microtubules → anti-inflammatory in gout.
D: Febuxostat also inhibits xanthine oxidase (newer agent).

Q68. Which drug causes gingival hyperplasia as a side effect?

A. Valproate
B. Phenytoin ✅
C. Carbamazepine
D. Ethosuximide

A: Valproate → hepatotoxicity, neural tube defects.
B: Phenytoin → gingival hyperplasia, hirsutism, teratogenicity.
C: Carbamazepine → agranulocytosis, SIADH.
D: Ethosuximide → GI upset, lethargy.

Q69. Which drug is used in hypertensive emergency, releasing NO?

A. Minoxidil
B. Nitroprusside ✅
C. Hydralazine
D. Diazoxide

A: Minoxidil opens K⁺ channels → vasodilation (used in severe HTN, alopecia).
B: Nitroprusside releases NO → immediate vasodilation, cyanide toxicity possible.
C: Hydralazine dilates arterioles, slower onset.
D: Diazoxide opens K⁺ channels, used in insulinoma as well.

Q70. Which opioid is used in diarrhea treatment (low abuse potential)?

A. Morphine
B. Loperamide ✅
C. Methadone
D. Fentanyl

A: Morphine is strong analgesic, high abuse potential.
B: Loperamide acts on μ receptors in gut → ↓motility, minimal CNS entry.
C: Methadone is used in opioid dependence.
D: Fentanyl is potent analgesic, risk of abuse.

Q71. Which drug is first-line for generalized absence seizures?

A. Phenytoin
B. Carbamazepine
C. Ethosuximide ✅
D. Valproate

A: Phenytoin ineffective in absence seizures.
B: Carbamazepine worsens absence seizures.
C: Ethosuximide blocks T-type Ca²⁺ channels in thalamus.
D: Valproate is second-line, also useful in mixed seizures.

Q72. Which insulin preparation has the longest duration of action?

A. NPH
B. Lispro
C. Glargine ✅
D. Regular insulin

A: NPH is intermediate-acting.
B: Lispro is rapid-acting.
C: Glargine is long-acting, peakless basal insulin.
D: Regular is short-acting.

Q73. Which drug inhibits 5-α-reductase, used in BPH?

A. Tamsulosin
B. Finasteride ✅
C. Flutamide
D. Leuprolide

A: Tamsulosin is α1A-blocker.
B: Finasteride blocks 5-α-reductase → ↓DHT, used in BPH and male baldness.
C: Flutamide is androgen receptor antagonist.
D: Leuprolide is GnRH analog.

Q74. Which drug is an H1 receptor antagonist with sedative properties?

A. Ranitidine
B. Diphenhydramine ✅
C. Loratadine
D. Famotidine

A: Ranitidine is H2 blocker.
B: Diphenhydramine is 1st-gen H1 blocker → sedative, anti-motion sickness.
C: Loratadine is 2nd-gen H1 blocker, less sedating.
D: Famotidine is H2 blocker.

Q75. Which drug is a TNF-α inhibitor used in rheumatoid arthritis?

A. Rituximab
B. Infliximab ✅
C. Trastuzumab
D. Imatinib

A: Rituximab targets CD20.
B: Infliximab is chimeric anti-TNF-α antibody → RA, Crohn’s disease.
C: Trastuzumab targets HER2.
D: Imatinib inhibits BCR-ABL tyrosine kinase.

Pharmacology MCQs — Part 4 (Q76–Q100)

Q76. Which opioid causes mydriasis instead of miosis in overdose?

A. Morphine
B. Meperidine (Pethidine) ✅
C. Methadone
D. Codeine

A: Morphine typically causes pinpoint pupils.
B: Meperidine toxicity → mydriasis due to antimuscarinic activity.
C: Methadone → miosis.
D: Codeine → miosis.

Q77. Which drug causes pulmonary fibrosis as a side effect?

A. Cyclophosphamide
B. Amiodarone ✅
C. Cisplatin
D. Vincristine

A: Cyclophosphamide → hemorrhagic cystitis.
B: Amiodarone → interstitial pulmonary fibrosis, thyroid and hepatic toxicity.
C: Cisplatin → nephrotoxicity, ototoxicity.
D: Vincristine → neuropathy.

Q78. Which drug is a muscarinic agonist used in postoperative urinary retention?

A. Atropine
B. Bethanechol ✅
C. Ipratropium
D. Scopolamine

A: Atropine blocks muscarinic receptors.
B: Bethanechol selectively stimulates M receptors in bladder/GI → treats urinary retention.
C: Ipratropium is muscarinic antagonist for asthma/COPD.
D: Scopolamine is anti-motion sickness drug.

Q79. Which cephalosporin is effective against Pseudomonas aeruginosa?

A. Cefazolin
B. Ceftriaxone
C. Ceftazidime ✅
D. Cefuroxime

A: Cefazolin (1st gen) → Gram-positive cocci.
B: Ceftriaxone (3rd gen) → broad Gram-neg coverage, not Pseudomonas.
C: Ceftazidime (3rd gen) active against Pseudomonas.
D: Cefuroxime (2nd gen) → moderate Gram-neg coverage.

Q80. Which drug is used for glaucoma and acts by inhibiting carbonic anhydrase?

A. Pilocarpine
B. Latanoprost
C. Acetazolamide ✅
D. Timolol

A: Pilocarpine is muscarinic agonist → ↑aqueous outflow.
B: Latanoprost is PGF2α analog → ↑outflow.
C: Acetazolamide inhibits carbonic anhydrase → ↓aqueous humor formation.
D: Timolol is β-blocker → ↓aqueous humor secretion.

Q81. Which antifungal binds ergosterol and forms pores in cell membrane?

A. Fluconazole
B. Caspofungin
C. Amphotericin B ✅
D. Terbinafine

A: Fluconazole inhibits ergosterol synthesis.
B: Caspofungin inhibits β-glucan synthesis.
C: Amphotericin B binds ergosterol → pore formation, leakage.
D: Terbinafine inhibits squalene epoxidase.

Q82. Which drug is a direct thrombin inhibitor?

A. Warfarin
B. Heparin
C. Dabigatran ✅
D. Rivaroxaban

A: Warfarin inhibits vitamin K-dependent clotting factor synthesis.
B: Heparin enhances antithrombin activity.
C: Dabigatran directly inhibits thrombin.
D: Rivaroxaban directly inhibits factor Xa.

Q83. Which drug is a prodrug that requires activation by bacterial catalase-peroxidase?

A. Rifampicin
B. Isoniazid ✅
C. Ethambutol
D. Pyrazinamide

A: Rifampicin inhibits RNA polymerase.
B: INH activated by KatG enzyme → inhibits mycolic acid synthesis.
C: Ethambutol inhibits arabinosyl transferase.
D: Pyrazinamide inhibits fatty acid synthase I.

Q84. Which drug causes “red man syndrome” due to histamine release?

A. Penicillin
B. Vancomycin ✅
C. Gentamicin
D. Linezolid

A: Penicillin → allergy, anaphylaxis.
B: Vancomycin rapid infusion → flushing, hypotension (“red man syndrome”).
C: Gentamicin → nephro/ototoxicity.
D: Linezolid → bone marrow suppression.

Q85. Which antipsychotic is safest in Parkinson’s disease psychosis?

A. Haloperidol
B. Clozapine ✅
C. Chlorpromazine
D. Fluphenazine

A: Haloperidol blocks D2 strongly → worsens Parkinsonism.
B: Clozapine has least D2 blockade → minimal motor worsening.
C: Chlorpromazine → strong D2 blockade.
D: Fluphenazine → high EPS risk.

Q86. Which drug is an H2 receptor blocker?

A. Omeprazole
B. Ranitidine ✅
C. Misoprostol
D. Sucralfate

A: Omeprazole is a proton pump inhibitor.
B: Ranitidine blocks H2 receptors → ↓acid secretion.
C: Misoprostol is a PGE1 analog.
D: Sucralfate is a mucosal coating agent.

Q87. Which agent is used to treat acetaminophen (paracetamol) overdose?

A. N-acetylcysteine ✅
B. Atropine
C. Flumazenil
D. Naloxone

A: N-acetylcysteine replenishes glutathione → detoxifies NAPQI metabolite.
B: Atropine treats organophosphate poisoning.
C: Flumazenil reverses benzodiazepine toxicity.
D: Naloxone reverses opioid toxicity.

Q88. Which drug is a selective β1-blocker?

A. Propranolol
B. Atenolol ✅
C. Labetalol
D. Carvedilol

A: Propranolol is nonselective β-blocker.
B: Atenolol is cardioselective (β1 > β2).
C: Labetalol blocks α1, β1, β2.
D: Carvedilol blocks α1, β1, β2.

Q89. Which chemotherapy drug stabilizes microtubules and prevents depolymerization?

A. Vincristine
B. Paclitaxel ✅
C. Etoposide
D. Methotrexate

A: Vincristine inhibits microtubule polymerization.
B: Paclitaxel “freezes” microtubules in metaphase → mitotic arrest.
C: Etoposide inhibits topoisomerase II.
D: Methotrexate inhibits DHFR.

Q90. Which drug is a P2Y12 receptor inhibitor?

A. Clopidogrel ✅
B. Abciximab
C. Aspirin
D. Heparin

A: Clopidogrel blocks ADP receptor (P2Y12) → inhibits platelet aggregation.
B: Abciximab blocks GPIIb/IIIa receptor.
C: Aspirin blocks COX-1 irreversibly.
D: Heparin enhances antithrombin activity.

Q91. Which antimalarial drug is contraindicated in G6PD deficiency?

A. Chloroquine
B. Artemether
C. Primaquine ✅
D. Mefloquine

A: Chloroquine safe in G6PD deficiency.
B: Artemether safe.
C: Primaquine causes hemolysis in G6PD deficiency.
D: Mefloquine safe.

Q92. Which antipsychotic is associated with hyperprolactinemia?

A. Olanzapine
B. Quetiapine
C. Risperidone ✅
D. Clozapine

A: Olanzapine → metabolic syndrome.
B: Quetiapine → sedation, low EPS.
C: Risperidone strongly blocks D2 → ↑prolactin (gynecomastia, amenorrhea).
D: Clozapine → agranulocytosis.

Q93. Which local anesthetic is most cardiotoxic?

A. Lidocaine
B. Prilocaine
C. Bupivacaine ✅
D. Procaine

A: Lidocaine is relatively safe.
B: Prilocaine → methemoglobinemia.
C: Bupivacaine → high cardiotoxicity, arrhythmias.
D: Procaine short-acting, low toxicity.

Q94. Which drug is an aldosterone antagonist used in heart failure?

A. Furosemide
B. Hydrochlorothiazide
C. Spironolactone ✅
D. Mannitol

A: Furosemide is a loop diuretic.
B: Hydrochlorothiazide is thiazide diuretic.
C: Spironolactone blocks aldosterone receptors → K⁺ sparing, HF benefit.
D: Mannitol is osmotic diuretic.

Q95. Which drug is an antiviral guanosine analog used in HSV infections?

A. Zidovudine
B. Acyclovir ✅
C. Oseltamivir
D. Ribavirin

A: Zidovudine is NRTI for HIV.
B: Acyclovir phosphorylated by viral thymidine kinase → inhibits viral DNA polymerase.
C: Oseltamivir is neuraminidase inhibitor (influenza).
D: Ribavirin used in RSV, hepatitis C.

Q96. Which drug is a long-acting β2 agonist used in asthma prophylaxis?

A. Albuterol
B. Salmeterol ✅
C. Ipratropium
D. Theophylline

A: Albuterol is short-acting β2 agonist.
B: Salmeterol is long-acting β2 agonist (LABA) for asthma prevention.
C: Ipratropium is muscarinic antagonist.
D: Theophylline is PDE inhibitor.

Q97. Which drug is used in opioid dependence as maintenance therapy?

A. Naloxone
B. Methadone ✅
C. Loperamide
D. Tramadol

A: Naloxone is an antagonist used in overdose, not maintenance.
B: Methadone is long-acting μ agonist → prevents withdrawal, used in de-addiction programs.
C: Loperamide is antidiarrheal.
D: Tramadol is weak μ agonist + SNRI, not for dependence therapy.

Q98. Which vitamin deficiency can isoniazid therapy cause?

A. Vitamin B1
B. Vitamin B2
C. Vitamin B6 (Pyridoxine) ✅
D. Vitamin B12

A: B1 deficiency → beriberi, Wernicke’s.
B: B2 deficiency → cheilosis.
C: INH depletes pyridoxine → neuropathy.
D: B12 deficiency → megaloblastic anemia.

Q99. Which chemotherapeutic agent causes hemorrhage and pulmonary fibrosis?

A. Bleomycin ✅
B. Vinblastine
C. Busulfan
D. Cisplatin

A: Bleomycin → pulmonary fibrosis, skin changes.
B: Vinblastine → bone marrow suppression.
C: Busulfan → pulmonary fibrosis, hyperpigmentation.
D: Cisplatin → nephrotoxicity.

Q100. Which drug is a 5-HT1B/1D agonist used in acute migraine?

A. Ergotamine
B. Sumatriptan ✅
C. Propranolol
D. Flunarizine

A: Ergotamine is also used in migraine but less specific.
B: Sumatriptan is selective 5-HT1B/1D agonist → vasoconstriction, ↓neurotransmitter release.
C: Propranolol is for migraine prophylaxis, not acute attack.
D: Flunarizine is Ca²⁺ channel blocker used in prophylaxis.

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