Biopharmaceutics Classification System (BCS) MCQs With Answer

Introduction:

Biopharmaceutics Classification System (BCS) MCQs With Answer is designed for M.Pharm students to strengthen their understanding of drug absorption, solubility, permeability and regulatory applications in modern biopharmaceutics. This collection combines conceptual questions and application-based scenarios reflecting current regulatory guidance, in vitro tools and formulation strategies. Practicing these targeted MCQs will help clarify how BCS guides biowaiver decisions, dissolution testing, permeability assays and formulation optimization (e.g., particle size reduction or salt selection). Each question includes concise options and the correct answer to facilitate rapid self-assessment and deeper study, aiding preparation for exams and for designing bioavailability-focused research in pharmaceutical development.

Q1. Which BCS class describes a drug with high solubility and high permeability?

• Class I
• Class II
• Class III
• Class IV

Correct Answer: Class I

Q2. According to regulatory BCS criteria, how is “high solubility” defined?

• The drug dissolves completely in 500 mL of water at 25°C
• The highest marketed dose is soluble in ≤250 mL of aqueous media over the pH range 1.0–7.5
• The drug has a solubility >1 mg/mL at pH 7.4
• The drug shows sink conditions in any single buffer

Correct Answer: The highest marketed dose is soluble in ≤250 mL of aqueous media over the pH range 1.0–7.5

Q3. Which criterion is most commonly used to define “high permeability” in BCS classification?

• Permeability >1 x 10^-6 cm/s in Caco-2 cells
• Extent of human absorption ≥90% of the administered dose
• Rapid disappearance from dissolution media
• High lipophilicity (log P >3)

Correct Answer: Extent of human absorption ≥90% of the administered dose

Q4. For a Class I immediate-release product, which dissolution characteristic commonly supports a biowaiver?

• At least 85% dissolution within 30 minutes in three media (pH 1.2, 4.5, 6.8)
• Complete dissolution within 120 minutes at pH 7.4 only
• Vendor-reported rapid wetting time
• Dissolution >50% in 30 minutes at a single pH

Correct Answer: At least 85% dissolution within 30 minutes in three media (pH 1.2, 4.5, 6.8)

Q5. Which BCS class represents low solubility but high permeability?

• Class I
• Class II
• Class III
• Class IV

Correct Answer: Class II

Q6. How does the Biopharmaceutics Drug Disposition Classification System (BDDCS) primarily differ from the BCS?

• BDDCS is based on extent of metabolism rather than solubility and permeability
• BDDCS uses solubility only, ignoring permeability
• BDDCS classifies drugs by dose strength exclusively
• BDDCS replaces dissolution testing with stability testing

Correct Answer: BDDCS is based on extent of metabolism rather than solubility and permeability

Q7. Which in vitro model is most frequently used to estimate human intestinal permeability for BCS purposes?

• PAMPA (Parallel Artificial Membrane Permeability Assay)
• Caco-2 cell monolayer assay
• Hepatocyte metabolic assay
• Shake-flask solubility test

Correct Answer: Caco-2 cell monolayer assay

Q8. A weakly basic drug will generally show increased aqueous solubility at which condition?

• High pH (alkaline) media
• Low pH (acidic) media
• Presence of lipids only
• At its isoelectric point

Correct Answer: Low pH (acidic) media

Q9. Which BCS class is most commonly eligible for regulatory biowaivers for immediate-release oral tablets?

• Class I
• Class II
• Class III
• Class IV

Correct Answer: Class I

Q10. For drugs in BCS Class II, which factor most often controls oral absorption variability?

• Permeability across the gut wall
• Dissolution and solubility in gastrointestinal fluids
• First-pass hepatic metabolism exclusively
• Stability in gastric acid only

Correct Answer: Dissolution and solubility in gastrointestinal fluids

Q11. Which excipient effect is relevant when assessing BCS-based biowaivers or formulation changes?

• Excipients may act as surfactants and alter drug solubility or membrane permeability
• Excipients cannot affect absorption and are always inert
• Any excipient only improves palatability and never affects dissolution
• Excipients only affect color and stability, not biopharmaceutics

Correct Answer: Excipients may act as surfactants and alter drug solubility or membrane permeability

Q12. In BCS solubility testing, “highest single therapeutic dose” refers to which of the following?

• The largest unit dose strength available or recommended clinically
• The smallest dose administered in pediatric use
• The average dose across all formulations
• The dose used in preclinical animal studies

Correct Answer: The largest unit dose available or recommended clinically

Q13. What is the main challenge associated with BCS Class IV drugs?

• They have high solubility but low permeability and are easy to formulate
• They have low solubility and low permeability, leading to poor and variable oral bioavailability
• They are only problematic for intravenous formulations
• They are usually highly metabolized and therefore have minimal absorption issues

Correct Answer: They have low solubility and low permeability, leading to poor and variable oral bioavailability

Q14. How does an in vitro–in vivo correlation (IVIVC) relate to BCS-based regulatory decisions?

• IVIVC can serve as a surrogate to predict in vivo performance when dissolution is the rate-limiting step
• IVIVC replaces all permeability testing in BCS
• IVIVC is irrelevant for biowaivers
• IVIVC only applies to intravenously administered drugs

Correct Answer: IVIVC can serve as a surrogate to predict in vivo performance when dissolution is the rate-limiting step

Q15. Which reference compound is commonly used as an in vivo marker of high human intestinal permeability?

• Amoxicillin
• Metoprolol
• Furosemide
• Ranitidine

Correct Answer: Metoprolol

Q16. Which USP dissolution apparatus is most commonly used for immediate-release oral tablets during BCS-related testing?

• Apparatus 1 (Basket)
• Apparatus 2 (Paddle)
• Apparatus 3 (Reciprocating Cylinder)
• Apparatus 4 (Flow-Through Cell)

Correct Answer: Apparatus 2 (Paddle)

Q17. Which formulation strategy is most appropriate to improve oral absorption of a BCS Class II drug?

• Particle size reduction (micronization or nanosizing) to increase dissolution rate
• Reducing dose strength while keeping particle size the same
• Removing disintegrants to slow tablet breakup
• Switching to a more hydrophobic salt form

Correct Answer: Particle size reduction (micronization or nanosizing) to increase dissolution rate

Q18. How does salt formation commonly affect an ionizable drug’s biopharmaceutic properties?

• Salt formation typically decreases solubility in aqueous media
• Salt formation can enhance aqueous solubility and hence dissolution rate
• Salt formation always reduces permeability across membranes
• Salt formation only affects tablet hardness, not solubility

Correct Answer: Salt formation can enhance aqueous solubility and hence dissolution rate

Q19. Which BCS class is characterized by high solubility but low permeability, making absorption permeability-limited?

• Class I
• Class II
• Class III
• Class IV

Correct Answer: Class III

Q20. Which pharmacokinetic factor can lead to underestimation of passive permeability and potential misclassification under BCS?

• Extensive plasma protein binding masking absorption
• Active efflux by intestinal transporters (e.g., P-glycoprotein) reducing net absorption
• High aqueous solubility across all pH values
• Low therapeutic dose strength only

Correct Answer: Active efflux by intestinal transporters (e.g., P-glycoprotein) reducing net absorption

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