Welcome, PharmD students, to this MCQ quiz on Intravenous (IV) Bolus Administration! The IV bolus route provides rapid drug delivery directly into the systemic circulation, leading to immediate therapeutic effects for certain medications. Understanding the unique pharmacokinetic profile following an IV bolus—including concepts like initial concentration, exponential decline, and parameters such as volume of distribution, clearance, and half-life derived from this administration—is crucial for effective drug therapy. This quiz will test your knowledge of one-compartment models, parameter calculation, and the principles of single and multiple IV bolus dosing. Let’s delve into the pharmacokinetics of rapid drug administration!
1. Intravenous (IV) bolus administration is characterized by:
- a) Slow infusion of a drug over several hours.
- b) Rapid injection of a drug directly into the systemic circulation.
- c) Administration of a drug via the gastrointestinal tract.
- d) Application of a drug onto the skin for systemic absorption.
Answer: b) Rapid injection of a drug directly into the systemic circulation.
2. In a one-compartment pharmacokinetic model following an IV bolus dose, which process is considered to occur instantaneously?
- a) Elimination
- b) Metabolism
- c) Absorption
- d) Distribution
Answer: d) Distribution
3. The initial plasma drug concentration (C0) immediately after an IV bolus dose in a one-compartment model can be calculated as:
- a) Dose × Volume of distribution (Vd)
- b) Dose / Volume of distribution (Vd)
- c) Dose × Clearance (CL)
- d) Dose / Clearance (CL)
Answer: b) Dose / Volume of distribution (Vd)
4. Following an IV bolus administration of a drug that exhibits first-order elimination, the plasma drug concentration declines:
- a) Linearly over time.
- b) Exponentially over time.
- c) Remains constant until the next dose.
- d) In a zero-order fashion.
Answer: b) Exponentially over time.
5. The equation describing drug concentration (Ct) at any time (t) after an IV bolus in a one-compartment model with first-order elimination is:
- a) Ct = C0 + kt
- b) Ct = C0 × e^(-kt)
- c) Ct = C0 / (1 + kt)
- d) Ct = k / C0
Answer: b) Ct = C0 × e^(-kt)
6. On a semi-logarithmic plot of plasma concentration versus time for a one-compartment IV bolus, first-order elimination is represented by:
- a) A curved line.
- b) A straight line with a positive slope.
- c) A straight line with a negative slope.
- d) A horizontal line.
Answer: c) A straight line with a negative slope.
7. The elimination rate constant (k) for a drug following first-order elimination after an IV bolus can be determined from the slope of which plot?
- a) Plasma concentration vs. time (linear scale)
- b) Log plasma concentration vs. time (semi-log scale)
- c) Amount of drug eliminated vs. time
- d) Dose vs. C0
Answer: b) Log plasma concentration vs. time (semi-log scale) (The slope is -k/2.303 for log base 10, or -k for natural log)
8. The elimination half-life (t½) of a drug is related to the elimination rate constant (k) by the equation:
- a) t½ = k / 0.693
- b) t½ = 0.693 × k
- c) t½ = 0.693 / k
- d) t½ = k + 0.693
Answer: c) t½ = 0.693 / k
9. If the elimination rate constant (k) of a drug is 0.1 hr⁻¹, what is its half-life?
- a) 1.44 hours
- b) 6.93 hours
- c) 10 hours
- d) 0.0693 hours
Answer: b) 6.93 hours (t½ = 0.693 / 0.1 hr⁻¹)
10. The volume of distribution (Vd) of a drug can be calculated after an IV bolus dose using data for the dose and:
- a) The elimination rate constant (k).
- b) The initial plasma concentration (C0).
- c) The area under the curve (AUC).
- d) The clearance (CL).
Answer: b) The initial plasma concentration (C0). (Vd = Dose / C0)
11. Clearance (CL) of a drug can be calculated from IV bolus data using the formula CL = k × Vd, where k is the elimination rate constant and Vd is the volume of distribution. It can also be calculated as:
- a) Dose × AUC
- b) Dose / AUC
- c) C0 / k
- d) AUC / Dose
Answer: b) Dose / AUC
12. The Area Under the Curve (AUC) from time zero to infinity for a drug eliminated by first-order kinetics after an IV bolus dose can be calculated as:
- a) C0 × k
- b) C0 / k
- c) Dose × k
- d) k / C0
Answer: b) C0 / k
13. If a 500 mg IV bolus dose of a drug results in an AUC₀-∞ of 50 mg·hr/L, what is the drug’s clearance?
- a) 0.1 L/hr
- b) 10 L/hr
- c) 25000 L/hr
- d) 5 L/hr
Answer: b) 10 L/hr (CL = Dose / AUC = 500 mg / 50 mg·hr/L)
14. When multiple IV bolus doses of a drug are given at regular intervals (shorter than 4-5 half-lives), what occurs?
- a) Drug concentration immediately drops to zero after each dose.
- b) Drug accumulation occurs until a steady state is reached.
- c) The half-life of the drug decreases with each dose.
- d) The volume of distribution increases with each dose.
Answer: b) Drug accumulation occurs until a steady state is reached.
15. At steady state (Css) with multiple IV bolus dosing, the amount of drug administered in a dosing interval equals:
- a) The amount of drug remaining from the previous dose.
- b) Half the amount of drug eliminated in that interval.
- c) The amount of drug eliminated in that dosing interval.
- d) The initial C0 after the first dose.
Answer: c) The amount of drug eliminated in that dosing interval.
16. The peak plasma concentration at steady state (Cmax,ss) after multiple IV bolus doses is:
- a) Lower than the Cmax after the first dose.
- b) Equal to the Cmax after the first dose.
- c) Higher than the Cmax after the first dose due to accumulation.
- d) Equal to C0.
Answer: c) Higher than the Cmax after the first dose due to accumulation.
17. The trough plasma concentration at steady state (Cmin,ss) after multiple IV bolus doses is the:
- a) Highest concentration achieved during the dosing interval.
- b) Lowest concentration observed just before administering the next dose.
- c) Average concentration over the dosing interval.
- d) Concentration immediately after the first dose.
Answer: b) Lowest concentration observed just before administering the next dose.
18. The accumulation factor (R) for multiple IV bolus dosing depends on the elimination rate constant (k) and the:
- a) Dose
- b) Volume of distribution (Vd)
- c) Dosing interval (τ)
- d) Clearance (CL)
Answer: c) Dosing interval (τ) (R = 1 / (1 – e^(-kτ)))
19. A primary advantage of IV bolus administration is:
- a) Avoidance of first-pass metabolism.
- b) Slower onset of action compared to oral administration.
- c) Reduced risk of adverse effects associated with high peak concentrations.
- d) Ease of self-administration by the patient.
Answer: a) Avoidance of first-pass metabolism. (Also rapid onset, 100% bioavailability)
20. A potential disadvantage of IV bolus administration is:
- a) Delayed therapeutic effect.
- b) Increased risk of immediate adverse reactions due to high initial drug concentrations.
- c) Low bioavailability.
- d) Inability to administer large volumes.
Answer: b) Increased risk of immediate adverse reactions due to high initial drug concentrations.
21. If an IV bolus dose of 100 mg produces an initial plasma concentration (C0) of 10 mg/L, the volume of distribution (Vd) is:
- a) 0.1 L
- b) 1 L
- c) 10 L
- d) 1000 L
Answer: c) 10 L (Vd = Dose / C0 = 100 mg / 10 mg/L)
22. For a drug administered by IV bolus, the rate of elimination at any time ‘t’ (assuming first-order kinetics) is equal to:
- a) k / Ct
- b) k × Ct × Vd (or k × Amount of drug in body at time t)
- c) Dose / Vd
- d) CL / Ct
Answer: b) k × Ct × Vd (or k × Amount of drug in body at time t)
23. If the dosing interval (τ) is equal to the drug’s half-life (t½) during multiple IV bolus dosing, the accumulation factor (R) will be:
- a) 1
- b) 2
- c) 0.5
- d) Infinity
Answer: b) 2 (R = 1 / (1 – e^(-kτ)). If τ = t½, then kτ = 0.693. e^(-0.693) ≈ 0.5. R = 1 / (1 – 0.5) = 1 / 0.5 = 2)
24. To rapidly achieve therapeutic concentrations for a drug with a long half-life given by multiple IV bolus doses, a clinician might administer a:
- a) Smaller maintenance dose.
- b) Loading dose.
- c) Placebo dose first.
- d) Dose via a different route.
Answer: b) Loading dose.
25. The average steady-state plasma concentration (Css,avg) after multiple IV bolus doses can be calculated as:
- a) Dose / (k × Vd)
- b) (Dose / τ) / CL
- c) Cmax,ss – Cmin,ss
- d) C0 / (1 – e^(-kτ))
Answer: b) (Dose / τ) / CL (Since Rate in = Rate out; Dose/τ = CL × Css,avg)
26. The time to reach steady state after starting multiple IV bolus dosing is determined by the drug’s:
- a) Dose
- b) Dosing interval
- c) Elimination half-life
- d) Volume of distribution
Answer: c) Elimination half-life (Approximately 4-5 half-lives)
27. If a drug’s clearance decreases (e.g., due to renal impairment) but the IV bolus dosing regimen (dose and interval) remains unchanged, the steady-state concentrations (Cmax,ss, Cmin,ss, Css,avg) will:
- a) Decrease
- b) Increase
- c) Remain the same
- d) Fluctuate more widely but the average will be the same
Answer: b) Increase
28. The one-compartment model assumes that the drug, after IV bolus administration:
- a) Distributes slowly into a peripheral compartment.
- b) Is eliminated before it distributes.
- c) Distributes rapidly and uniformly throughout the body (considered as a single compartment).
- d) Is only present in the plasma.
Answer: c) Distributes rapidly and uniformly throughout the body (considered as a single compartment).
29. If the volume of distribution (Vd) of a drug is very small (e.g., 3-5 L), it suggests the drug is primarily confined to the:
- a) Adipose tissue
- b) Intracellular fluid
- c) Plasma compartment
- d) Total body water
Answer: c) Plasma compartment
30. The area under the first moment curve (AUMC) divided by the AUC gives the:
- a) Mean Residence Time (MRT)
- b) Clearance
- c) Volume of distribution at steady state
- d) Half-life
Answer: a) Mean Residence Time (MRT)
31. For an IV bolus, bioavailability (F) is assumed to be:
- a) 0
- b) 0.5 (50%)
- c) 1 (100%)
- d) Variable depending on the dose
Answer: c) 1 (100%)
32. If the dosing interval (τ) for multiple IV bolus doses is significantly longer than 5 half-lives of the drug, then:
- a) Significant accumulation will occur.
- b) Steady state will never be reached.
- c) There will be virtually no accumulation, and each dose will behave like a single dose.
- d) The drug will exhibit zero-order kinetics.
Answer: c) There will be virtually no accumulation, and each dose will behave like a single dose.
33. The fluctuation between Cmax,ss and Cmin,ss during multiple IV bolus dosing is minimized by:
- a) Using larger doses at longer intervals.
- b) Using smaller doses at shorter intervals (or continuous infusion).
- c) Increasing the drug’s half-life.
- d) Decreasing the drug’s clearance.
Answer: b) Using smaller doses at shorter intervals (or continuous infusion).
34. The primary advantage of plotting ln(Concentration) vs. time for IV bolus data is that it allows for easier determination of the:
- a) Volume of distribution directly.
- b) Elimination rate constant (k) from the linear slope.
- c) Dose administered.
- d) Absorption rate constant.
Answer: b) Elimination rate constant (k) from the linear slope.
35. If C0 is the initial concentration after an IV bolus, the concentration after one half-life (t½) will be:
- a) C0
- b) 2 × C0
- c) C0 / 2
- d) C0 / 4
Answer: c) C0 / 2
36. The total amount of drug in the body immediately after an IV bolus dose is equal to:
- a) C0 × Vd
- b) The administered dose
- c) CL × AUC
- d) k × Vd
Answer: b) The administered dose (As C0 = Dose/Vd, so Dose = C0*Vd which is amount in body at t=0)
37. Knowing the pharmacokinetic parameters from a single IV bolus dose helps in:
- a) Only determining the drug’s chemical structure.
- b) Designing appropriate multiple-dosing regimens.
- c) Predicting the drug’s color.
- d) Manufacturing the drug product.
Answer: b) Designing appropriate multiple-dosing regimens.
38. The slope of the ln(C) vs. time plot for a one-compartment IV bolus is equal to:
- a) k (elimination rate constant)
- b) -k (negative elimination rate constant)
- c) t½ (half-life)
- d) Vd (volume of distribution)
Answer: b) -k (negative elimination rate constant)
39. To maintain a desired average steady-state concentration (Css,avg), if a drug’s clearance (CL) is halved, the dosing rate (Dose/τ) should ideally be:
- a) Doubled
- b) Halved
- c) Kept the same
- d) Quartered
Answer: b) Halved (Css,avg = (Dose/τ)/CL. If CL is halved, Dose/τ must be halved to keep Css,avg same)
40. The equation Cmax,ss = C0 / (1 – e^(-kτ)) is used to calculate the peak concentration at steady state for multiple IV bolus doses. C0 here refers to:
- a) The initial concentration after the very first dose if no accumulation occurred.
- b) The trough concentration at steady state.
- c) The average steady state concentration.
- d) The concentration at the end of the dosing interval.
Answer: a) The initial concentration after the very first dose if no accumulation occurred. (C0 = Dose/Vd)
41. The concept of “superposition” in multiple dosing pharmacokinetics assumes that:
- a) Each dose eliminates the previous dose completely.
- b) The pharmacokinetics of the drug (k, Vd, CL) do not change with repeated dosing.
- c) The drug follows zero-order kinetics.
- d) The patient’s condition improves with each dose.
Answer: b) The pharmacokinetics of the drug (k, Vd, CL) do not change with repeated dosing.
42. Which pharmacokinetic parameter is independent of the dose for drugs following linear (first-order) kinetics after IV bolus administration?
- a) C0
- b) AUC (AUC is dose-proportional)
- c) Clearance (CL) and Half-life (t½)
- d) Cmax,ss
Answer: c) Clearance (CL) and Half-life (t½) (C0 and AUC are dose-dependent; Cmax,ss is also dose-dependent)
43. A drug with a very short half-life (e.g., minutes) given as an IV bolus will:
- a) Accumulate significantly even with long dosing intervals.
- b) Be rapidly eliminated, and its effects may be transient unless given by continuous infusion or frequent boluses.
- c) Always require a loading dose.
- d) Primarily distribute to adipose tissue.
Answer: b) Be rapidly eliminated, and its effects may be transient unless given by continuous infusion or frequent boluses.
44. If the therapeutic range for a drug is very narrow, careful consideration of Cmax,ss and Cmin,ss after multiple IV bolus doses is important to:
- a) Ensure the drug is affordable.
- b) Maximize patient convenience.
- c) Avoid toxicity at peak and maintain efficacy at trough.
- d) Only determine the color of the IV bag.
Answer: c) Avoid toxicity at peak and maintain efficacy at trough.
45. The amount of drug eliminated during one dosing interval (τ) at steady state after multiple IV bolus doses is equal to:
- a) The loading dose.
- b) The maintenance dose administered during that interval.
- c) Half the maintenance dose.
- d) Cmin,ss × Vd.
Answer: b) The maintenance dose administered during that interval.
46. If Vd increases while k remains constant, C0 after an IV bolus dose will:
- a) Increase
- b) Decrease
- c) Remain the same
- d) Become zero
Answer: b) Decrease (C0 = Dose/Vd)
47. If k increases (shorter half-life) while Vd remains constant, C0 after an IV bolus dose will:
- a) Increase
- b) Decrease
- c) Remain the same
- d) Become unpredictable
Answer: c) Remain the same (C0 = Dose/Vd, independent of k for the initial concentration)
48. The rate of drug decline from C0 after an IV bolus is determined by:
- a) Only Vd
- b) Only CL
- c) The elimination rate constant (k)
- d) The dose
Answer: c) The elimination rate constant (k)
49. IV bolus administration is often used for drugs that:
- a) Require slow absorption.
- b) Need to achieve rapid and predictable therapeutic concentrations.
- c) Are very unstable in solution.
- d) Are intended for local effects only.
Answer: b) Need to achieve rapid and predictable therapeutic concentrations.
50. Understanding the pharmacokinetics of IV bolus administration helps pharmacists optimize therapy by:
- a) Only choosing the correct needle size.
- b) Designing dosing regimens, predicting concentrations, and anticipating effects of patient variability on drug disposition.
- c) Solely focusing on drug cost.
- d) Administering all medications themselves.
Answer: b) Designing dosing regimens, predicting concentrations, and anticipating effects of patient variability on drug disposition. Sources