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PharmD clinical pharmacy program Level 3, Semester 2 Biopharmaceutics & Pharmacokinetics (PT608(

CHAPTER SUMMARY

❖ Pharmacokinetic parameters use simplifying assumptions to better

understand the relationship of drug concentrations in the body to drug response.

❖ The one-compartment model assumes that the drug is uniformly distributed

within a single hypothetical compartment volume from which the drug
concentration can be sampled and assayed easily.

❖ The one-compartment model, IV bolus drug injection, provides the simplest
approach for estimating the apparent volume of distribution, V d, and the

elimination rate constant, k.
❖ If Vd, k, and the drug dose are known, the model equation allows drug

concentration in the compartment (body) at any time to be calculated.

❖ The volumes of plasma fluid and extracellular fluid may be relatively constant

under normal conditions.

❖ However, these volumes added together do not usually numerically equal to the

(apparent) volume of distribution of the drug, which may be larger or smaller

depending on how widely the drug distributes into tissues.

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