Drug interactions related to transporters MCQs With Answer

Drug interactions related to transporters MCQs With Answer

This quiz set focuses on transporter-mediated drug interactions — a crucial component of Modern Bio‑Analytical Techniques for M.Pharm students. It covers major uptake and efflux transporters (P‑gp, BCRP, OATP, OAT, OCT, MATE, MRP), mechanisms of inhibition and induction, common clinical examples, genetic impacts, and in vitro/in vivo extrapolation strategies used in bioanalytical and DDI assessment. Questions are designed to deepen your understanding of how transporters alter drug absorption, distribution, clearance and toxicity, and how these effects are investigated experimentally and interpreted for regulatory decision‑making. Use these MCQs to reinforce conceptual knowledge and practical considerations for transporter‑related DDIs.

Q1. Which of the following is a major efflux transporter implicated in multidrug resistance and many drug–drug interactions?

• P-glycoprotein (P-gp/ABCB1)
• OATP1B1 (SLCO1B1)
• OCT2 (SLC22A2)
• MATE1 (SLC47A1)

Correct Answer: P-glycoprotein (P-gp/ABCB1)

Q2. A competitive inhibitor of P-gp co‑administered with a P-gp substrate is most likely to cause which effect?

• Decrease intracellular concentration of the substrate
• Increase intracellular concentration of the substrate
• No change in substrate exposure
• Immediate enzymatic degradation of the substrate

Correct Answer: Increase intracellular concentration of the substrate

Q3. Which of the following drugs is a well‑recognized clinical inhibitor of P-gp?

• Rifampin
• Verapamil
• Probenecid
• Metformin

Correct Answer: Verapamil

Q4. Polymorphism in which transporter gene (SLCO1B1) is associated with increased risk of statin‑induced myopathy?

• OATP1B1 (SLCO1B1)
• P-gp (ABCB1)
• BCRP (ABCG2)
• OCT1 (SLC22A1)

Correct Answer: OATP1B1 (SLCO1B1)

Q5. Which transporter mediates the primary uptake of metformin from blood into renal proximal tubular cells?

• OATP1B1
• OCT2 (SLC22A2)
• P-gp (ABCB1)
• BCRP (ABCG2)

Correct Answer: OCT2 (SLC22A2)

Q6. Inhibition of which renal apical transporters reduces renal secretion of metformin and can increase systemic exposure?

• OATP1B1 and OATP1B3
• MATE1 and MATE2‑K (apical renal transporters)
• P-gp and BCRP
• MRP2 and MRP3

Correct Answer: MATE1 and MATE2‑K (apical renal transporters)

Q7. Which in vitro approaches are commonly used to study transporter‑mediated drug–drug interactions during drug development?

• Vesicular transport assays
• HEK‑293 or transfected cell uptake assays
• Caco‑2 monolayer efflux studies
• All of the above

Correct Answer: All of the above

Q8. Breast Cancer Resistance Protein (BCRP/ABCG2) primarily performs which role relevant to drug handling?

• Energy‑independent uptake into hepatocytes
• Apical efflux limiting oral absorption and fetal exposure
• Mitochondrial drug metabolism
• Glomerular filtration enhancement

Correct Answer: Apical efflux limiting oral absorption and fetal exposure

Q9. Which drug pair is a classic example of a P-gp mediated clinical drug–drug interaction?

• Simvastatin and gemfibrozil
• Digoxin and quinidine
• Warfarin and rifampin
• Metformin and insulin

Correct Answer: Digoxin and quinidine

Q10. In in vitro-to-in vivo extrapolation (IVIVE) for transporter inhibition, an R‑value greater than 1.1 generally indicates what?

• No interaction expected
• Potential for in vivo drug–drug interaction warranting further evaluation
• Definitive clinical toxicity
• Immediate need to withdraw the drug

Correct Answer: Potential for in vivo drug–drug interaction warranting further evaluation

Q11. Which parameter is commonly reported to quantify inhibitor potency against a transporter in vitro?

• Km
• Vmax
• IC50
• CLint

Correct Answer: IC50

Q12. Which of the following is a commonly used clinical probe substrate for OATP1B1 in DDI studies?

• Fexofenadine
• Pravastatin
• Digoxin
• Ranitidine

Correct Answer: Pravastatin

Q13. Which transporter (ABC family) plays a key role in biliary excretion of conjugated bilirubin and certain drugs?

• BCRP (ABCG2)
• Multidrug resistance‑associated protein 2 (MRP2/ABCC2)
• P-gp (ABCB1)
• OATP2B1

Correct Answer: Multidrug resistance‑associated protein 2 (MRP2/ABCC2)

Q14. Which statement about transporter induction is correct?

• Induction typically increases substrate plasma exposure
• Induction usually decreases substrate exposure by enhancing clearance
• Induction is caused by transporter inhibitors
• Induction has no time dependency and occurs immediately

Correct Answer: Induction usually decreases substrate exposure by enhancing clearance

Q15. Transporter‑mediated DDIs most directly alter which pharmacokinetic parameter representing systemic exposure?

• Volume of distribution (Vd)
• AUC (area under the plasma concentration–time curve)
• Bioanalytical assay recovery
• Protein binding constant

Correct Answer: AUC (area under the plasma concentration–time curve)

Q16. Which bioanalytical challenge is specifically important when evaluating transporter‑mediated DDIs?

• Requirement to measure intracellular drug concentrations in addition to plasma
• Only measuring total radioactivity is sufficient
• Transporter DDIs do not require metabolite analysis
• Ignoring protein binding is acceptable

Correct Answer: Requirement to measure intracellular drug concentrations in addition to plasma

Q17. Which in vitro cell model is widely used to study intestinal absorption and efflux transporter function?

• HepG2 hepatocyte monolayers
• Caco‑2 cell monolayers
• Primary neuronal cultures
• Red blood cell ghosts

Correct Answer: Caco‑2 cell monolayers

Q18. Which best describes the inhibition constant Ki for transporter studies?

• Ki varies directly with substrate concentration and is not useful
• Ki is an apparent parameter equal to IC90
• Ki represents inhibitor binding affinity and is independent of substrate concentration
• Ki denotes the transporter expression level

Correct Answer: Ki represents inhibitor binding affinity and is independent of substrate concentration

Q19. Methotrexate renal secretion is primarily mediated by which transporters?

• OATP1B1 and OATP1B3
• OAT1 and OAT3 (organic anion transporters)
• P-gp (ABCB1)
• OCT1 and OCT2

Correct Answer: OAT1 and OAT3 (organic anion transporters)

Q20. Regulatory guidances typically recommend assessment of transporter interactions for which set of transporters?

• Only CYP enzymes, transporters are not required
• P-gp, BCRP, OATP1B1/1B3, OAT1/3, OCT2 and MATE1/2‑K
• Glutathione transferases and sulfotransferases
• Only hepatic CYP3A4 and CYP2D6

Correct Answer: P-gp, BCRP, OATP1B1/1B3, OAT1/3, OCT2 and MATE1/2‑K

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