Modes of excretion MCQs With Answer

Introduction: Understanding the Modes of excretion MCQs With Answer is essential for B. Pharm students preparing for pharmacology, pharmacokinetics, and clinical pharmacy exams. This Student-friendly primer summarizes renal, hepatic, pulmonary, biliary, sweat, salivary, and mammary routes of drug elimination, key determinants like molecular size, protein binding, pH partitioning, glomerular filtration, tubular secretion/reabsorption, enterohepatic recirculation, and clinical implications for dosing and toxicity. Targeted practice using MCQs enhances retention of mechanisms, clearance concepts, and drug-specific excretion patterns. Clear, exam-focused questions help bridge theory and practice for safer therapeutic decisions. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which organ is the primary site for excretion of most hydrophilic drugs and their metabolites?

• Liver
• Kidney
• Lungs
• Skin

Correct Answer: Kidney

Q2. Glomerular filtration primarily depends on which of the following drug properties?

• Protein binding
• Lipid solubility
• pKa
• Rate of metabolism

Correct Answer: Protein binding

Q3. Tubular secretion in the kidney is mainly an active process located in which part of the nephron?

• Glomerulus
• Proximal tubule
• Loop of Henle
• Collecting duct

Correct Answer: Proximal tubule

Q4. Which mechanism explains increased excretion of weak acids by alkalinizing urine?

• Active transport
• Ion trapping (pH partitioning)
• Protein binding displacement
• Increased glomerular filtration

Correct Answer: Ion trapping (pH partitioning)

Q5. Biliary excretion is especially important for which type of compounds?

• Very small hydrophilic molecules
• Large, polar conjugates with molecular weight > 300–500 Da
• Inert gases
• Highly protein-bound free radicals

Correct Answer: Large, polar conjugates with molecular weight > 300–500 Da

Q6. Enterohepatic recirculation affects drug disposition by which process?

• Increasing renal clearance
• Reabsorption of drug from the intestine after biliary secretion
• Metabolism to inactive metabolites only
• Enhancing pulmonary excretion

Correct Answer: Reabsorption of drug from the intestine after biliary secretion

Q7. Pulmonary excretion is most significant for drugs that are:

• Highly ionized
• Volatile gases or low molecular weight volatile substances
• Extensively protein bound
• Large polar conjugates

Correct Answer: Volatile gases or low molecular weight volatile substances

Q8. Which of the following increases drug reabsorption in renal tubules?

• Low lipid solubility
• High degree of ionization
• High lipid solubility and non-ionized form
• Active tubular secretion inhibitors

Correct Answer: High lipid solubility and non-ionized form

Q9. Milk excretion of drugs is most affected by:

• Drug molecular weight exclusively
• Milk-to-plasma pH difference and lipid solubility
• Renal clearance only
• Presence of bile acids

Correct Answer: Milk-to-plasma pH difference and lipid solubility

Q10. Salivary excretion is clinically important because:

• It is the main route of drug elimination for all drugs
• It can provide noninvasive monitoring of free drug levels
• All drugs concentrate in saliva
• It prevents enterohepatic recirculation

Correct Answer: It can provide noninvasive monitoring of free drug levels

Q11. Which transporter family is primarily involved in hepatic uptake and biliary excretion of many drugs?

• P-glycoprotein (ABCB1) only
• Organic anion transporting polypeptides (OATPs) and ATP-binding cassette (ABC) transporters
• Monoamine oxidases
• CYP450 enzymes

Correct Answer: Organic anion transporting polypeptides (OATPs) and ATP-binding cassette (ABC) transporters

Q12. Protein binding reduces renal excretion primarily by:

• Blocking tubular secretion pumps
• Decreasing the free (unbound) fraction available for glomerular filtration
• Increasing hepatic metabolism
• Enhancing biliary excretion

Correct Answer: Decreasing the free (unbound) fraction available for glomerular filtration

Q13. A drug with high renal clearance relative to GFR suggests which process?

• Only glomerular filtration
• Active tubular secretion in addition to filtration
• No renal handling
• Only passive reabsorption

Correct Answer: Active tubular secretion in addition to filtration

Q14. Cholescintigraphy and bile sampling help study which excretion mode?

• Renal filtration
• Hepatic biliary excretion
• Pulmonary exhalation
• Sweat gland secretion

Correct Answer: Hepatic biliary excretion

Q15. Which physiological change in neonates affects drug excretion compared to adults?

• Increased renal glomerular filtration rate at birth
• Immature renal tubular function and lower GFR initially
• Exclusively biliary excretion maturation complete at birth
• Higher hepatic metabolism than adults

Correct Answer: Immature renal tubular function and lower GFR initially

Q16. Which clinical intervention increases urinary excretion of weak bases?

• Administering ammonium chloride to acidify urine
• Administering sodium bicarbonate to alkalinize urine
• Giving probenecid
• Administering bile sequestrants

Correct Answer: Administering ammonium chloride to acidify urine

Q17. Probenecid affects excretion of some drugs by:

• Enhancing CYP450 activity
• Inhibiting renal tubular secretion of organic anions
• Alkalinizing urine
• Stimulating bile flow

Correct Answer: Inhibiting renal tubular secretion of organic anions

Q18. The clearance concept that combines renal and hepatic elimination into a single measure is called:

• Volume of distribution
• Total body clearance
• Bioavailability
• Protein binding coefficient

Correct Answer: Total body clearance

Q19. Which phase II reaction typically increases water solubility facilitating renal excretion?

• Oxidation by CYP450
• Glucuronidation
• Hydrolysis by esterases only
• Photodegradation

Correct Answer: Glucuronidation

Q20. A drug with significant enterohepatic recycling is likely to show which pharmacokinetic feature?

• Shortened half-life
• Multiple plasma concentration peaks and prolonged elimination
• No oral absorption
• Immediate renal clearance only

Correct Answer: Multiple plasma concentration peaks and prolonged elimination

Q21. Which lab measure best estimates glomerular filtration of a drug in clinical practice?

• Serum creatinine clearance (eGFR)
• Urine pH
• Hepatic enzyme levels
• Salivary concentration

Correct Answer: Serum creatinine clearance (eGFR)

Q22. Which statement about drug excretion in sweat is correct?

• Sweat is a major elimination route for large polar drugs
• Sweat can contribute to dermal exposure and odor but is a minor route of systemic elimination
• Sweat excretion is independent of drug lipophilicity
• Sweat excretion always reduces systemic toxicity significantly

Correct Answer: Sweat can contribute to dermal exposure and odor but is a minor route of systemic elimination

Q23. P-glycoprotein (P-gp) in the kidney and liver mainly affects excretion by:

• Promoting intracellular drug metabolism
• Actively pumping drugs into bile or urine, reducing intracellular accumulation
• Increasing glomerular filtration rate
• Changing plasma protein binding

Correct Answer: Actively pumping drugs into bile or urine, reducing intracellular accumulation

Q24. Which factor least influences renal drug excretion?

• Renal blood flow
• Urine flow rate
• Drug pKa relative to urine pH
• Rate of gastric emptying

Correct Answer: Rate of gastric emptying

Q25. Which analytical method is commonly used to measure drug concentrations in plasma or urine for excretion studies?

• Thin-layer chromatography without detection
• High-performance liquid chromatography (HPLC) with mass spectrometry
• Naked eye color observation
• Pulse oximetry

Correct Answer: High-performance liquid chromatography (HPLC) with mass spectrometry

Q26. Renal clearance of inulin is used experimentally because inulin is:

• Actively secreted
• Freely filtered and neither reabsorbed nor secreted
• Highly protein bound
• Strongly metabolized by the kidney

Correct Answer: Freely filtered and neither reabsorbed nor secreted

Q27. Which drug is primarily eliminated unchanged in the urine and requires dose adjustment in renal impairment?

• Warfarin
• Gentamicin
• Propranolol
• Diazepam

Correct Answer: Gentamicin

Q28. Hepatic clearance of a drug is influenced by three main factors summed in the well-stirred model. Which is NOT one of them?

• Hepatic blood flow
• Intrinsic clearance (enzyme activity)
• Fraction unbound in blood
• Renal glomerular filtration rate

Correct Answer: Renal glomerular filtration rate

Q29. Which process reduces biliary excretion and may increase systemic exposure?

• Cholestasis (impaired bile flow)
• Enhanced phase II conjugation
• Upregulation of OATP transporters
• Increased enterohepatic cycling

Correct Answer: Cholestasis (impaired bile flow)

Q30. Drugs that are weak acids are generally cleared more when urine is:

• Acidic
• Alkaline
• Neutral only
• Highly proteinaceous

Correct Answer: Alkaline

Q31. Which clinical scenario would most likely reduce renal excretion of a highly protein-bound drug?

• Hypoalbuminemia increasing free fraction
• Drug displacement increasing free fraction transiently
• Renal impairment decreasing GFR
• Administration of diuretics increasing urine flow

Correct Answer: Renal impairment decreasing GFR

Q32. Which drug elimination half-life parameter is directly related to clearance and volume of distribution?

• Half-life (t1/2) = (0.693 × Vd) / Clearance
• Half-life is independent of Vd and clearance
• Half-life equals clearance divided by Vd
• Half-life equals bioavailability times clearance

Correct Answer: Half-life (t1/2) = (0.693 × Vd) / Clearance

Q33. Which of the following drugs undergoes significant pulmonary excretion and is monitored via exhaled breath?

• Isoflurane
• Insulin
• Warfarin
• Digoxin

Correct Answer: Isoflurane

Q34. Saliva as a sampling matrix best reflects which drug fraction?

• Total (bound + unbound) plasma concentration
• Only protein-bound fraction
• Free unbound plasma concentration for many drugs
• Metabolite concentration exclusively

Correct Answer: Free unbound plasma concentration for many drugs

Q35. Renal tubular reabsorption of weak bases is enhanced when urine is made:

• More acidic
• More alkaline
• Neutralized with buffers
• Protein-rich

Correct Answer: More alkaline

Q36. Which drug interaction can reduce biliary excretion of co-administered substrates?

• Induction of CYP3A4
• Inhibition of hepatic transporters like BSEP or MRP2
• Increased renal blood flow
• Activation of salivary secretion

Correct Answer: Inhibition of hepatic transporters like BSEP or MRP2

Q37. For a drug eliminated by first-order kinetics, doubling the dose will:

• Double the elimination half-life
• Double the steady-state concentration (assuming linear kinetics)
• Halve the clearance
• Make elimination saturable immediately

Correct Answer: Double the steady-state concentration (assuming linear kinetics)

Q38. Which statement about renal secretion and reabsorption competition is TRUE?

• Two drugs competing for the same tubular secretion transporter can increase renal excretion of both
• Competition for secretion transporters can reduce clearance and increase plasma levels of one or both drugs
• Competition always leads to increased elimination and reduced toxicity
• Tubular reabsorption is independent of transporter-mediated processes

Correct Answer: Competition for secretion transporters can reduce clearance and increase plasma levels of one or both drugs

Q39. Which factor promotes biliary excretion of drugs conjugated to glucuronic acid?

• Low molecular weight < 100 Da
• Conjugation increases polarity and molecular size facilitating active transport into bile
• Conjugation reduces biliary transport
• High plasma protein binding ensures biliary excretion

Correct Answer: Conjugation increases polarity and molecular size facilitating active transport into bile

Q40. Which urine test would detect unmetabolized parent drug for excretion study?

• Serum enzyme panel
• Urine drug screening by chromatography or immunoassay
• Complete blood count
• Liver function tests

Correct Answer: Urine drug screening by chromatography or immunoassay

Q41. Which of the following increases renal clearance of a weak acid drug?

• Acidifying urine
• Alkalinizing urine
• Decreasing urine flow
• Increasing protein binding

Correct Answer: Alkalinizing urine

Q42. Phase I metabolic reactions typically prepare drugs for excretion by:

• Converting drugs to more polar metabolites via oxidation, reduction, or hydrolysis
• Directly conjugating them with glucuronic acid only
• Sequestering drugs in adipose tissue forever
• Removing conjugates in bile exclusively

Correct Answer: Converting drugs to more polar metabolites via oxidation, reduction, or hydrolysis

Q43. Renal clearance less than GFR suggests which of the following?

• Net tubular secretion
• Net tubular reabsorption or high protein binding
• No renal handling
• Clearance equals zero

Correct Answer: Net tubular reabsorption or high protein binding

Q44. Which transporter in hepatocytes mediates canalicular secretion of organic anions into bile?

• GLUT4
• BSEP (Bile Salt Export Pump) and MRP2
• Na+/K+ ATPase exclusively
• Monoamine oxidase

Correct Answer: BSEP (Bile Salt Export Pump) and MRP2

Q45. Which clinical condition would most likely decrease hepatic clearance of high-extraction drugs?

• Increased hepatic blood flow
• Reduced hepatic blood flow such as in heart failure or shock
• Induction of metabolizing enzymes
• Increased transporter activity

Correct Answer: Reduced hepatic blood flow such as in heart failure or shock

Q46. Which method can be used to enhance elimination of phenobarbital in overdose?

• Urine alkalinization to promote excretion of the weak acid
• Urine acidification to trap the drug in plasma
• Administering P-gp inhibitors
• Decreasing urine flow

Correct Answer: Urine alkalinization to promote excretion of the weak acid

Q47. A drug that is extensively metabolized to active metabolites may show which excretion pattern?

• Only parent drug in urine
• Both parent drug and metabolites in urine and bile, prolonging pharmacologic effect
• No excretion at all
• Excretion exclusively via sweat

Correct Answer: Both parent drug and metabolites in urine and bile, prolonging pharmacologic effect

Q48. Which property most favors urinary excretion rather than biliary excretion?

• High molecular weight > 500 Da
• Small molecular size < 300 Da and high water solubility
• Large conjugated polar metabolites
• Strong affinity for hepatocyte transporters

Correct Answer: Small molecular size < 300 Da and high water solubility

Q49. In renal failure, dosing adjustments are typically required for drugs primarily eliminated by:

• Hepatic metabolism only
• Renal excretion of unchanged drug
• Pulmonary excretion exclusively
• Salivary elimination only

Correct Answer: Renal excretion of unchanged drug

Q50. Which factor would most likely increase the renal elimination of a drug cleared by glomerular filtration?

• Severe proteinuria decreasing free drug in plasma
• Increased free fraction due to displacement from plasma proteins
• Decrease in renal blood flow
• Inhibition of filtration barrier

Correct Answer: Increased free fraction due to displacement from plasma proteins

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

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