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Pharmacokinetics


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SingHealth Clinical Pharmacology provides pharmacokinetic services that can be exploratory or extensive according to the clients' requirements.

Determination of pharmacokinetic parameters such as the area under the concentration-time curve (AUC), half-life, clearance, and volume of distribution require measurement of analytes in the biological samples. These often require highly sensitive analytical equipment for quantitation. With our in-house bioanalytical capabilities, we are able to support both small and large molecule preclinical studies as well as clinical trial programmes.








Our range of pharmacokinetic services include:

Advice on Preclinical and Early Phase Clinical Trial Study Design

  • Sample size
  • Dose and dosing intervals
  • Sampling intervals


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Bioavailability and Bioequivalence Studies

Bioavailability is a measurement of the extent of a therapeutically active medicine that reaches the systemic circulation and is therefore available at the site of action.

Commonly assessed using three main pharmacokinetic variables:

  • Area under the blood drug concentration versus time curve (AUC)
  • Maximum blood concentration (Cmax)
  • Time to reach maximum concentration (Tmax)









Bioequivalence
is a property whereby if two drugs are bioequivalent, there is no clinically significant difference in their bioavailability. In order to determine that two medicines are bioequivalent, there must be no more than a 20% difference between the AUC and Cmax (based on international consensus).

Commonly assessed for

  • Between generic and innovator drugs
  • Between early and late clinical trial formulations
  • Between formulations used in trials and products to be marketed
  • Changes in formulation after innovator product has been approved


Non-Compartmental and Compartmental Pharmacokinetic Analysis
There are two common approaches to understanding a drug's pharmacokinetics:

Compartmental methods consider the body to consist of a finite number of interconnected, well-mixed, and kinetically homogeneous compartments such as blood and other tissues/organs. Based upon this perspective, certain assumptions and models are made based upon nonlinear regression analysis to describe the PK of the drug.

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Adapted from Turner RM et al, 2015. Wiley Interdiscip Rev Syst Biol Med.

Noncompartmental analysis (NCA) methods are model-independent (do not rely upon assumptions about body compartments). In addition, an NCA relies almost exclusively upon algebraic equations to estimate PK parameters, making the analysis less complex than compartmental methods.

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Adapted from Turner RM et al, 2015. Wiley Interdiscip Rev Syst Biol Med.


Population Pharmacokinetic Modelling

Commonly used to identify and quantify sources of variability in drug concentration in a patient population. These form the parameters to look into the associations between patient characteristics and differences in pharmacokinetics, which can then be used to customise pharmacotherapy.


Softwares for Pharmacokinetics Analyses

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Phoenix WinNonlin                           NONMEM7