Dosing pattern and drug therapy based on pharmacokinetic and disease state MCQs With Answer

Dosing pattern and drug therapy based on pharmacokinetic and disease state MCQs With Answer

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Effective dosing patterns and drug therapy require understanding pharmacokinetics and disease-state physiology. This review introduces key concepts — absorption, distribution, metabolism, elimination, half-life, clearance, and volume of distribution — and applies them to dose calculation: loading dose, maintenance dose, dosing interval, and adjustments for renal or hepatic impairment, age, obesity, and dialysis. Emphasis on therapeutic drug monitoring, steady-state principles, one- and multi-compartment models, and non-linear kinetics prepares B. Pharm students to individualize therapy and minimize toxicity. These MCQs include calculation problems and clinical scenarios to build competence. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. What does the elimination half-life of a drug represent?

  • The time for the dose to be completely eliminated
  • The time for plasma concentration to decrease by 10%
  • The time for plasma concentration to decrease by half
  • The time for the drug to reach peak concentration

Correct Answer: The time for plasma concentration to decrease by half

Q2. Which equation correctly relates elimination half-life (t1/2) to elimination rate constant (Ke)?

  • t1/2 = 0.693 × Ke
  • t1/2 = 0.693 / Ke
  • t1/2 = Ke / 0.693
  • t1/2 = 1 / (0.693 × Ke)

Correct Answer: t1/2 = 0.693 / Ke

Q3. What is the correct formula for calculating a loading dose (LD)?

  • LD = (Cl × Css) / F
  • LD = (Vd × Css) / F
  • LD = (Ke × Css) / F
  • LD = (Dose × Tau) / F

Correct Answer: LD = (Vd × Css) / F

Q4. Which expression gives the maintenance infusion rate required to achieve a target steady-state concentration (Css)?

  • Rate = (Cl × Css) / F
  • Rate = (Vd × Css) / F
  • Rate = (Ke × Vd) / Css
  • Rate = (Dose × F) / Tau

Correct Answer: Rate = (Cl × Css) / F

Q5. How is total body clearance (Cl) related to volume of distribution (Vd) and elimination rate constant (Ke)?

  • Cl = Vd / Ke
  • Cl = Ke / Vd
  • Cl = Ke × Vd
  • Cl = Vd × t1/2

Correct Answer: Cl = Ke × Vd

Q6. Approximately how many half-lives are required to reach >95% of steady-state concentration with first-order kinetics?

  • 1 half-life
  • 2 half-lives
  • 4–5 half-lives
  • 10 half-lives

Correct Answer: 4–5 half-lives

Q7. What is the pharmacokinetic definition of bioavailability (F)?

  • The fraction of unchanged drug reaching systemic circulation after administration
  • The fraction of drug bound to plasma proteins
  • The rate of elimination divided by absorption rate
  • The volume of distribution divided by clearance

Correct Answer: The fraction of unchanged drug reaching systemic circulation after administration

Q8. Which statement best describes first-order elimination kinetics?

  • Elimination rate is constant regardless of concentration
  • Elimination rate is independent of plasma concentration
  • Elimination rate is proportional to plasma concentration
  • Elimination follows a fixed amount per dosing interval

Correct Answer: Elimination rate is proportional to plasma concentration

Q9. The one-compartment model assumes which of the following about drug distribution?

  • Instantaneous and uniform distribution throughout the body
  • Two distinct phases: distribution and elimination separate
  • Distribution limited to the vascular compartment only
  • Drug distributes only into adipose tissue

Correct Answer: Instantaneous and uniform distribution throughout the body

Q10. Which drug is a classic example of non-linear (saturable) pharmacokinetics?

  • Amoxicillin
  • Phenytoin
  • Gentamicin
  • Metoprolol

Correct Answer: Phenytoin

Q11. Therapeutic index (TI) is best defined as which ratio?

  • ED50 / TD50
  • LD50 / ED50
  • TD50 / ED50
  • Minimum toxic concentration / minimum effective concentration

Correct Answer: TD50 / ED50

Q12. Which clinical scenario most strongly indicates the need for therapeutic drug monitoring (TDM)?

  • Drug with a wide therapeutic index and linear kinetics
  • Short-acting OTC analgesics
  • Drug with narrow therapeutic index and high pharmacokinetic variability
  • Topical agents with minimal systemic absorption

Correct Answer: Drug with narrow therapeutic index and high pharmacokinetic variability

Q13. When adjusting dosing for renal impairment, which parameter is most commonly used to estimate drug clearance?

  • AST/ALT values
  • Creatinine clearance (CrCl) estimated by Cockcroft-Gault
  • Body surface area (BSA)
  • Serum albumin

Correct Answer: Creatinine clearance (CrCl) estimated by Cockcroft-Gault

Q14. Which scoring system is commonly used to assess hepatic function for dose adjustment?

  • APACHE II score
  • Glasgow Coma Scale
  • Child–Pugh score
  • CHA2DS2-VASc score

Correct Answer: Child–Pugh score

Q15. What is the primary purpose of administering a loading dose?

  • To reduce clearance
  • To rapidly achieve target plasma concentration
  • To decrease drug toxicity over time
  • To extend the half-life of the drug

Correct Answer: To rapidly achieve target plasma concentration

Q16. Which is an advantage of continuous intravenous infusion over intermittent bolus dosing?

  • Produces higher peak concentrations and more toxicity
  • Prevents accumulation at steady state
  • Maintains more stable plasma concentrations with reduced fluctuation
  • Eliminates the need to know clearance

Correct Answer: Maintains more stable plasma concentrations with reduced fluctuation

Q17. For lipophilic drugs in obese patients, which pharmacokinetic parameter is most likely to increase?

  • Renal clearance
  • Volume of distribution
  • Plasma protein binding
  • Fraction unbound in plasma

Correct Answer: Volume of distribution

Q18. What are the SI units of clearance commonly expressed as in clinical practice?

  • mg/L
  • L/h or mL/min
  • mol/L
  • mg/kg

Correct Answer: L/h or mL/min

Q19. A significant first-pass hepatic metabolism will most directly affect which parameter?

  • Volume of distribution
  • Clearance via kidneys
  • Oral bioavailability (F)
  • Plasma protein binding

Correct Answer: Oral bioavailability (F)

Q20. Approximately how many half-lives are required to reach about 90% of steady-state concentration?

  • 1 half-life
  • 2 half-lives
  • 3.3 half-lives
  • 8 half-lives

Correct Answer: 3.3 half-lives

Q21. Dose proportionality across a range of doses typically indicates which kinetic behavior?

  • Non-linear (saturable) kinetics
  • Zero-order elimination
  • Linear (first-order) kinetics
  • Flip-flop kinetics

Correct Answer: Linear (first-order) kinetics

Q22. For a drug significantly removed by hemodialysis, which dosing strategy is most appropriate?

  • Give the usual dose immediately before dialysis
  • Avoid dosing adjustments; dialysis does not matter
  • Administer supplemental dose after dialysis or adjust timing
  • Double the dose on dialysis days

Correct Answer: Administer supplemental dose after dialysis or adjust timing

Q23. The maintenance oral dose per dosing interval (Dose) to achieve Css is given by which formula?

  • Dose = (Css × Vd × Tau) / F
  • Dose = (Css × Cl × Tau) / F
  • Dose = (Ke × Vd × Css) / F
  • Dose = (Css × Ke) / (Cl × F)

Correct Answer: Dose = (Css × Cl × Tau) / F

Q24. Which factor most influences peak-trough fluctuation for a given drug and dose?

  • Bioavailability (F)
  • Dosing interval (Tau)
  • Volume of distribution
  • Plasma protein binding

Correct Answer: Dosing interval (Tau)

Q25. If clearance of a drug decreases while volume of distribution remains constant, what happens to half-life?

  • Half-life decreases
  • Half-life increases
  • Half-life remains unchanged
  • Half-life becomes zero-order

Correct Answer: Half-life increases

Q26. High hepatic extraction ratio drugs are most sensitive to changes in which physiological parameter?

  • Hepatic blood flow
  • Plasma protein binding
  • Renal excretion
  • Volume of distribution

Correct Answer: Hepatic blood flow

Q27. What is the clinical implication of high plasma protein binding for a drug?

  • Only total concentration determines effect
  • Only unbound (free) concentration is pharmacologically active
  • Protein binding has no effect on clearance
  • All bound drug is filtered by the kidney

Correct Answer: Only unbound (free) concentration is pharmacologically active

Q28. Pediatric dose adjustments are most commonly based on which of the following?

  • Adult fixed dose always
  • Body weight (mg/kg) or body surface area
  • Serum creatinine only
  • Age in years only

Correct Answer: Body weight (mg/kg) or body surface area

Q29. Which statement describes zero-order kinetics?

  • Rate of elimination decreases with concentration
  • Rate of elimination is proportional to concentration
  • Rate of elimination is a constant amount per unit time regardless of concentration
  • Rate of elimination is dependent on renal blood flow only

Correct Answer: Rate of elimination is a constant amount per unit time regardless of concentration

Q30. A patient requires target plasma concentration (Css) of 10 mg/L. If Vd = 40 L and F = 1, what loading dose will achieve the target?

  • 40 mg
  • 100 mg
  • 400 mg
  • 4,000 mg

Correct Answer: 400 mg

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