PK/PD model

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PK/PD modeling (pharmacokinetic/pharmacodynamic modeling) (alternatively abbreviated as PKPD [1] or PK-PD [2] modeling) is a technique that combines the two classical pharmacologic disciplines of pharmacokinetics and pharmacodynamics. [3] It integrates a pharmacokinetic and a pharmacodynamic model component into one set of mathematical expressions that allows the description of the time course of effect intensity in response to administration of a drug dose. PK/PD modeling is related to the field of pharmacometrics.

Central to PK/PD models is the concentration-effect or exposure-response relationship. [4] A variety of PK/PD modeling approaches exist to describe exposure-response relationships. PK/PD relationships can be described by simple equations such as linear model, Emax model or sigmoid Emax model. [5] However, if a delay is observed between the drug administration and the drug effect, a temporal dissociation needs to be taken into account and more complex models exist: [6] [7]

PK/PD modeling has its importance at each step of the drug development [9] [10] and it has shown its usefulness in many diseases. [11] The Food and Drug Administration also provides guidances for Industry to recommend how exposure-response studies should be performed. [12]

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Drug tolerance or drug insensitivity is a pharmacological concept describing subjects' reduced reaction to a drug following its repeated use. Increasing its dosage may re-amplify the drug's effects; however, this may accelerate tolerance, further reducing the drug's effects. Drug tolerance is indicative of drug use but is not necessarily associated with drug dependence or addiction. The process of tolerance development is reversible and can involve both physiological factors and psychological factors.

<span class="mw-page-title-main">Pharmacodynamics</span> Area of Academic Study

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