Non-renal routes of drug excretion MCQs With Answer

Non-renal routes of drug excretion MCQs With Answer

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Non-renal routes of drug excretion MCQs With Answer
Non-renal routes of drug excretion encompass biliary, faecal, pulmonary, salivary, sweat, breast milk, dermal and other minor pathways essential for comprehensive pharmacokinetics. Topics include mechanisms (biliary secretion, enterohepatic recycling, pulmonary exhalation, ion trapping in saliva and milk), determinants (molecular weight, lipophilicity, plasma protein binding, transporters like OATP, P-gp, MRP2), and clinical implications (dose adjustment in hepatic impairment, neonatal exposure, drug interactions). Understanding these routes helps predict drug disposition, toxicity and monitoring strategies beyond renal clearance. Focused MCQs below probe transporter roles, physicochemical influences and clinical relevance. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which route is most important for elimination of large molecular-weight glucuronide conjugates?

  • Biliary excretion
  • Renal glomerular filtration
  • Pulmonary exhalation
  • Sweat secretion

Correct Answer: Biliary excretion

Q2. Which transporter is primarily responsible for ATP-dependent canalicular efflux of many drugs into bile?

  • Organic anion transporting polypeptide (OATP)
  • P-glycoprotein (P-gp)
  • Albumin
  • Cytochrome P450

Correct Answer: P-glycoprotein (P-gp)

Q3. Enterohepatic recycling of a drug most commonly leads to which pharmacokinetic effect?

  • Prolonged elimination half-life
  • Reduced oral bioavailability
  • Enhanced renal clearance
  • Immediate hepatic metabolism

Correct Answer: Prolonged elimination half-life

Q4. Pulmonary excretion is most significant for which type of drugs?

  • Volatile, low molecular-weight agents
  • Highly protein-bound peptides
  • Large conjugated glucuronides
  • Ionized polar electrolytes

Correct Answer: Volatile, low molecular-weight agents

Q5. Which parameter most directly affects the rate of pulmonary excretion of an inhaled or volatile drug?

  • Blood-gas partition coefficient
  • Renal clearance
  • Hepatic microsomal activity
  • Sweat gland density

Correct Answer: Blood-gas partition coefficient

Q6. Milk-to-plasma drug concentration ratio is primarily influenced by which property?

  • Degree of ionization (pKa and pH differences)
  • Renal tubular secretion
  • Presence of bile salts in milk
  • Pulmonary ventilation

Correct Answer: Degree of ionization (pKa and pH differences)

Q7. Detection of which class of drugs in sweat and saliva is commonly used in forensic or workplace testing?

  • Amphetamines
  • Insulin peptides
  • Low molecular weight steroids
  • Injectable heparins

Correct Answer: Amphetamines

Q8. Phase II conjugation (e.g., glucuronidation) typically affects biliary excretion by:

  • Increasing molecular weight and often promoting biliary elimination
  • Reducing molecular weight and increasing renal filtration only
  • Decreasing water solubility and preventing excretion
  • Directly inhibiting hepatic transporters

Correct Answer: Increasing molecular weight and often promoting biliary elimination

Q9. Impairment of which organ most directly reduces biliary and many non-renal excretory pathways?

  • Liver
  • Kidney
  • Lung
  • Skin

Correct Answer: Liver

Q10. Which of the following is NOT a non-renal route of drug excretion?

  • Bile
  • Lungs (exhalation)
  • Renal urine
  • Sweat

Correct Answer: Renal urine

Q11. Saliva drug concentrations are often used in therapeutic monitoring because saliva generally reflects:

  • The unbound (free) plasma concentration of drug
  • Total bound plus unbound plasma concentration
  • Only metabolites, not parent drug
  • Hepatic enzyme activity directly

Correct Answer: The unbound (free) plasma concentration of drug

Q12. Drugs with a high hepatic extraction ratio have clearance most dependent on which factor?

  • Hepatic blood flow
  • Plasma protein binding only
  • Renal blood flow
  • Pulmonary ventilation

Correct Answer: Hepatic blood flow

Q13. Uptake of many drugs into hepatocytes from blood is mediated by which transporter family?

  • Organic anion transporting polypeptides (OATPs)
  • P-glycoprotein (P-gp)
  • Na+/K+ ATPase pumps
  • CYP450 enzymes

Correct Answer: Organic anion transporting polypeptides (OATPs)

Q14. Which statement about enterohepatic recycling is correct?

  • It can produce secondary peaks in plasma concentration–time profiles
  • It always eliminates drugs faster from the body
  • It prevents any renal excretion of the drug
  • It depends solely on glomerular filtration

Correct Answer: It can produce secondary peaks in plasma concentration–time profiles

Q15. Neonatal exposure through breast milk is most likely for which type of drug?

  • Lipophilic weak bases with low protein binding
  • Highly protein-bound acidic drugs
  • Large polar conjugates only excreted in bile
  • Inhaled gaseous anesthetics

Correct Answer: Lipophilic weak bases with low protein binding

Q16. Inhibition of canalicular transporters such as MRP2 or P-gp will most likely cause:

  • Reduced biliary secretion and increased systemic drug exposure
  • Increased pulmonary elimination
  • Enhanced renal filtration
  • Immediate increase in sweat excretion

Correct Answer: Reduced biliary secretion and increased systemic drug exposure

Q17. Sweat excretion preferentially removes drugs that are:

  • Small, hydrophilic and unbound
  • High molecular-weight lipophilic conjugates
  • Strongly protein-bound acidic drugs
  • Exclusively metabolized by CYP450

Correct Answer: Small, hydrophilic and unbound

Q18. Which category of drugs is predominantly eliminated unchanged by exhalation?

  • Volatile anesthetic agents
  • Large peptide hormones
  • Conjugated glucuronides
  • Ingested heavy metals

Correct Answer: Volatile anesthetic agents

Q19. A low blood/gas partition coefficient indicates:

  • The drug rapidly equilibrates into alveolar gas and is more readily exhaled
  • Drug is tightly retained in blood and poorly exhaled
  • Drug is highly protein-bound in plasma only
  • Drug is exclusively eliminated in bile

Correct Answer: The drug rapidly equilibrates into alveolar gas and is more readily exhaled

Q20. For biliary excretion, drugs typically have which characteristics?

  • Higher molecular weight and often conjugated (e.g., glucuronides)
  • Extremely low molecular weight and neutral polarity
  • Exclusive renal clearance only
  • Complete resistance to hepatic uptake

Correct Answer: Higher molecular weight and often conjugated (e.g., glucuronides)

Q21. Which transporter is specifically important for bile salt secretion into bile?

  • Bile salt export pump (BSEP)
  • Organic cation transporter 2 (OCT2)
  • Glutathione peroxidase
  • Sodium-glucose cotransporter (SGLT)

Correct Answer: Bile salt export pump (BSEP)

Q22. A secondary rise in plasma concentration after an oral dose most likely indicates:

  • Enterohepatic recycling or enteroenteric reabsorption
  • Complete first-pass metabolism without reabsorption
  • Immediate renal elimination only
  • Accelerated pulmonary clearance

Correct Answer: Enterohepatic recycling or enteroenteric reabsorption

Q23. Which drug property tends to increase transfer into breast milk?

  • Low plasma protein binding
  • Extensive hepatic conjugation only
  • Very high molecular weight (>1000 Da)
  • Exclusive elimination via lungs

Correct Answer: Low plasma protein binding

Q24. Presence of an unchanged drug in feces may indicate which of the following?

  • Incomplete absorption or biliary excretion of parent drug
  • Renal filtration of the drug
  • Exclusive pulmonary elimination
  • Immediate metabolism to volatile metabolites

Correct Answer: Incomplete absorption or biliary excretion of parent drug

Q25. Which factor would NOT increase pulmonary excretion of a volatile drug?

  • High blood-gas partition coefficient
  • Increased minute ventilation
  • Large alveolar surface area
  • Low blood-gas partition coefficient

Correct Answer: High blood-gas partition coefficient

Q26. Detection of drugs in hair or nails is most useful for demonstrating:

  • Chronic or historical exposure over weeks to months
  • Instantaneous plasma concentration at dosing
  • Only renal impairment status
  • Immediate pulmonary elimination rates

Correct Answer: Chronic or historical exposure over weeks to months

Q27. Inhibition of P-gp at the canalicular membrane is most likely to:

  • Reduce biliary excretion and raise systemic drug levels
  • Increase renal tubular secretion directly
  • Enhance sweat gland elimination
  • Convert drug into volatile metabolites

Correct Answer: Reduce biliary excretion and raise systemic drug levels

Q28. The phenomenon where a weak base accumulates in milk due to pH differences is called:

  • Ion trapping
  • Enterohepatic cycling
  • Pulmonary partitioning
  • Conjugative metabolism

Correct Answer: Ion trapping

Q29. MRP2 (multidrug resistance-associated protein 2) is primarily involved in:

  • Canalicular export of conjugated organic anions into bile
  • Glomerular filtration of small molecules
  • Transport across alveolar epithelium into air
  • Oxidative metabolism by hepatocytes

Correct Answer: Canalicular export of conjugated organic anions into bile

Q30. In cholestasis, biliary excretion of drugs is typically:

  • Decreased, causing higher plasma concentrations of bile-excreted drugs
  • Increased, leading to rapid clearance of all drugs
  • Unaffected because only renal routes compensate
  • Converted to pulmonary excretion automatically

Correct Answer: Decreased, causing higher plasma concentrations of bile-excreted drugs

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