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Dr. Chad Briscoe
Posted by Dr. Chad Briscoe Pharmacokinetics

The Difference Between Pharmacokinetics and Pharmacodynamics

The Difference Between Pharmacokinetics and Pharmacodynamics

In the United States, the safety and efficacy of prescription and over-the-counter drugs are a top priority for our government, medical professionals, and pharmaceutical companies. The Food and Drug Administration (FDA) is responsible for protecting public health by ensuring that any and all available medications are safe for human consumption, especially with regard to approving new medications or deciding whether or not a drug should be taken off the market. That even includes veterinary drugs and biological products as well.

The cost of creating and testing a single drug can swell from the hundreds of millions into the billions. According to a 2017 report from The Journal of the American Medical Association (JAMA), the median cost of developing a single cancer drug was $648 million. While that is still a hefty sum of money, others have argued that the price of bringing a drug from invention to pharmacy shelves can be upwards of $2.7 billion.

The efficacy and safety of a specific drug depend heavily on pharmacokinetics and pharmacodynamics. We’re going to explain the difference between pharmacokinetics and pharmacodynamics and why they are so important during the research, development and usage of a drug.

The Difference Between Pharmacokinetics & Pharmacodynamics

Before we go into further detail, let’s differentiate between pharmacokinetics and pharmacodynamics. The difference between pharmacokinetics (PK) and pharmacodynamics (PD) can be summed up pretty simply. Pharmacokinetics is the study of what the body does to the drug, and Pharmacodynamics is the study of what the drug does to the body.

Another easy way to remember what pharmacokinetics means is to reference the definition of ‘kinetics’. Kinetics essentially means movement, but by definition, it is the study of forces acting on mechanisms. So pharmacokinetics refers to the movement of any drug going into, through, and out of the body.

Scientifically speaking, pharmacokinetics studies the rates of chemical reactions within the body. When referring to pharmaceuticals, pharmacokinetics would outline the timeline of the drug’s absorption, bioavailability, distribution, metabolism and how your body excretes it.

A fun and effective way of remembering what pharmacodynamics means is to think of the word ‘dynamo’. Dynamo typically refers to energy or power. But in terms of pharmacodynamics, it refers to how the drug works and how it exerts its power on the body. When it comes to pharmaceuticals, pharmacodynamics focuses on receptor binding, post-receptor effects and chemical interactions. It’s fairly simple to remember these two incredibly intimidating terms when you jot those buzz words down in your brain.

Large Molecule Bioanalytical Studies

Typically, large molecule bioanalysis includes immunogenicity assessment, biomarker measures, and of course, pharmacokinetics (PK) and pharmacodynamics (PD) studies. Biotherapeutics are analyzed within a biological matrix, which is typically in the form of serum or plasma.

Large molecule pharmacodynamic (PD) studies analyze the biochemical and physiological effects that the drug has on the patient. These bioanalyses are vital to fully understanding a drug, therapeutic, or product before introducing it to the public.

Both non-clinical and clinical studies require quantitative bioanalysis of the biotherapeutic being tested. In both cases, a known quantity of the biotherapeutic is dosed and samples are collected to determine the pharmacokinetic properties of the drug.

When it comes to large molecule quantitation, BioAgilytix is a top performer. BioAgilytix has over a decade of experience supporting a wide array of biotherapeutic bioanalysis. This experience includes PK assays using serum, plasma, and cerebrospinal fluid to name a few. Our biomedical testing solutions are delivered with specialized knowledge and a personalized approach, ensuring expedient analysis, accurate results, and reporting that is customized to your workflows.

Why PK & PD Analyses Are Important

As The National Institutes of Health (NIH) so plainly put it, “Characterizing the relationship between the pharmacokinetics (PK, concentration vs. time) and pharmacodynamics (PD, effect vs. time) is an important tool in the discovery and development of new drugs in the pharmaceutical industry.” When it comes to developing responsible drug treatments it is extremely important that pharmaceutical companies and prescribers have accurate data as it pertains to dosage and PD effect. This essential data is derived from the non-clinical and clinical studies conducted prior to approval, informing the proper dose that is eventually delivered to patients.

Nearly 500 years ago, Swiss physician and chemist Paracelsus expressed the basic principle of toxicology: “All things are poison and nothing is without poison; only the dose makes a thing not a poison.” Today, we would simply say it’s “too much of a good thing…”You can see why it is extremely important to understand the exact dosage, side effects, intensity, and how long a patient can use a specific drug to maximize the beneficial effects while minimizing any associated toxicities.

BioAgilytix PK Assays & PD Assessment Services

BioAgilytix provides a wide range of pharmacokinetic and pharmacodynamic services including assay development and validation on multiple platforms and matrices. Our expertise includes preclinical and clinical support, assay development/validation, regulated sample analysis, and CLIA-certified clinical testing.

BioAgilytix believes that simplicity, clarity, and quality lead to good decisions. Common sense drug development requires an understanding of complex PK and PD principles. We are well-versed in the factors that could influence the validity of the data generated by these assays, and take those complexities into account during method development to ensure optimal results. We have never received a 483 notice in the history of BioAgilytix.

The scientists at BioAgilytix are experienced in supporting PK assessments in a variety of species including rodents, humans, and non-human primates, and in multiple matrices such as serum, plasma, urine, and saliva.

Our team has a clear understanding of the ability of the assay to detect the drug in the sample matrix. We conduct our high-quality PK assay procedures and results strictly in compliance with GLP / GMP regulations and in accordance with international regulatory standards (FDA, EMEA, ICH).

For pharmacodynamic studies, our team brings extensive experience in developing receptor occupancy assays in soluble proteins, such as Bruton’s tyrosine kinase (Btk). Btk regulates the proliferation and survival of cancer cells in various B-cell lymphoid malignancies, and we have successfully developed, optimized, and validated various ELISA-based, GLP-compliant assays to determine the Btk occupancy in PBMC lysates.

Our Boston lab is capable of acting as a central laboratory for Phase I/II studies, from sample collection kit preparation to whole blood PBMC isolation and processing and lysate sample preparation to receptor occupancy testing.

BioAgilytix is the clear choice for PK/PD assay development and analysis with accuracy, reliability and world-class expertise. Contact us today for more information on our wide range of bioanalysis services.

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