Pharmacokinetic Studies vs. Pharmacodynamic Studies: A Comparative Analysis

The US FDA has the responsibility of protecting the health of the general public by ensuring all drug products coming to the market are safe and effective. They have the primary responsibility of approving new drug medication and deciding whether to discontinue any current drug in the market. These assessments also include biological products and veterinary drugs. 

Today the cost of developing a single drug product can involve billions of dollars and may take up to 10 to 15 years to reach the market shelf. The safety and efficacy of a drug product largely depend on its pharmacokinetic and pharmacodynamic properties. Therefore the current article compares both pharmacokinetic studies and pharmacodynamic studies. Besides, it also discusses the importance of pharmacokinetic and pharmacodynamic parameters during drug research and development. 

The difference between pharmacokinetic study and pharmacodynamic study

The difference between pharmacokinetic and pharmacodynamic studies is pretty simple. Pharmacokinetic studies involve understanding the effect an organism has on the drug product, whereas pharmacodynamic studies involve assessing the drug’s effects on the body. 

Kinetics, by definition, refers to movement. Hence pharmacokinetics includes assessing the drug movement through the body. In scientific terms, pharmacokinetic assessments include the rate of chemical reactions happening within an organism. These chemical reactions are associated with the absorption, bioavailability, distribution, metabolism, and excretion characteristics of a drug product. 

On the other hand, the term dynamics in pharmacodynamics can be referred to as power or energy. Hence, pharmacodynamics typically relates to the drug’s effect or power on an organism. Pharmacodynamic studies focus on chemical interactions, receptor binding, and post-receptor effects. 

As PK studies the ADME properties of a drug product, pharmacodynamics involves evaluating biomolecular and biochemical interactions. However, pharmacokinetics and pharmacodynamics data are crucial to assess the exposure-response relationship. Understanding the PK/PD relationship is essential for developing and approving pharmaceutical drug products. Almost 25% of the information on drug labels and drug package inserts comes from PK/ PD data. Therefore a strategic approach including thorough planning of pharmacokinetic and pharmacodynamic design can help accelerate the development of safe and effective drug products. 

Importance of pharmacokinetic and pharmacodynamic studies

Understanding the relationship between the PK (concentration versus time) data and PD (effect versus time) data is necessary for discovering and developing new drug products. PK/PD data are a vital component of IND studies. Only a robust and thorough PK/PD analysis during preclinical development will prove crucial for the approval of human studies. Moreover, similar to preclinical evaluations, continual PK/PD clinical trials are necessary for modifying drug doses in subsequent stages of clinical studies. 

Accurate pharmacodynamic effects and usage data are critical for developing and delivering reliable drug treatments. This vital information comes from PK/PD evaluations during nonclinical and clinical studies that inform an ideal therapeutic dose for the patient population. 

Pharmacokinetic and pharmacodynamic data can help researchers design better clinical trials relating to how different molecules interact and the doses that can be used and modified according to the patient population. Moreover, physicians use PK/PD data on package inserts or drug labels to treat different patient populations. For example, pharmacokinetic and pharmacodynamic data can help clinicians prescribe the drug to the younger versus elderly population or patients with and without kidney issues.

Must Read: Understanding the Fundamentals of MSD PK Assay in Preclinical Research