Pharmacokinetic (PK) assay studies the relationship between drug concentration and metabolites with time. The pharmacokinetic study evaluates the concentration-time profile through specific parameters such as volume of distribution, clearance, area under the curve, half-life, bioavailability, and maximum concentrations. These parameters describe how living systems influence drug concentration, including absorption, distribution, metabolism, and excretion.
PK parameters are highly dependent on drug properties. PK analysis in clinical trials and drug discovery focuses on deriving information about structural modification to improve PK characteristics. Besides, toxicity and efficacy are related to pharmacokinetics. Hence, pharmacokinetic/pharmacodynamic (PK/PD) models are generally derived to plan and interpret in-vivo studies for toxicity, efficacy, and safety testing. The current article describes approaches for streamlining pharmacokinetic services.
Fast-tracking pharmacokinetic services
PK/PD studies during drug development require input from complementary disciplines of the biopharmaceutical industry. Integrating PK/PD models in early drug development helps identify ideal compounds and accelerate pharmacokinetic testing.
PK/PD assessments are a robust approach to combining quantitative data on pharmacologic properties with drug pharmacokinetics. This study design assumes a causal relationship between therapeutic activity and drug exposure. These types of relationships are often complex. Hence, robust preclinical studies with appropriate designs are critical to building relevant PK/PD models. As more data becomes accessible, preliminary models can be defined following an iterative approach. The ultimate output will be a powerful tool that would have been developed through an in-depth understanding of method requirements for efficacy and accuracy.
A well-designed PK/PD model offers an efficient method for informative drug development. It can help us understand the mechanism of drug action and select ideal drug compounds. Employing PK/PD models in early drug discovery and development can shorten the development timeline, minimize animal usage, predict dose ranges, and estimate therapeutic index. PK/PD models help integrate data from different studies based on an in-depth understanding of disease and drug biology.
Generally, a core team in the drug discovery industry will gather information and reports about animal models and study designs. Hence, a partnership between pharmacokinetics and pharmacologists is essential as early as possible in the drug discovery program. Besides, this collaboration should continue throughout different stages of drug development and beyond into the post-marketing phase. Moreover, a healthy discussion between partners and stakeholders in pharmacology development will help address critical questions related to pharmacokinetic testing.
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A robust approach to instill confidence in PK/PD models is to begin with the reference compound that has external or internal reports available. In instances where such data is unavailable, sponsors may find it beneficial to invest resources to generate complete data for a reference compound before initiating pharmacokinetic testing. Although this is a significant preliminary investment, having an extensive and in-depth understanding of PK/PD relationships will likely decrease the investment in the long term.
Furthermore, early discussion and engagement with multi-disciplinary teams can help refine and implement PK/PD strategies. Besides, as new data emerges from initial studies, different teams can devise an appropriate hypothesis to define the PK/PD model. Most importantly, as more individuals come to a consensus for defining the role of PK/PD data, it will be beneficial to begin plans for translating PK/PD data into different development phases of research.