What is the difference between Pharmacology and Pharmacokinetics? Are they related at all? What are their roles in the development of medicine? Studying both Pharmacology and Pharmacodynamics is beneficial to any student wanting to pursue a career in either area.
Pharmacology deals with the action of a compound on a cell, organ or tissue. This includes the absorption, metabolism and excretion of a wide range of chemicals and other compounds. Pharmacology also includes the study of how these chemicals and compounds interact with the biological systems that regulate the activities of these cells and systems. In this regards, one can consider Pharmacology as a science of cellular processes. A successful career in Pharmacology requires both broad knowledge of the physiology and chemistry of tissues and the ability to perform experiments and measurements.
Pharmacokinetics on the other hand is the process of controlling and monitoring the concentration and rate of protein binding to a membrane, organelle, cell, etc. This involves the use of a combination of techniques for such control. Kinetic Analysis is a method to measure the binding of a molecule to a membrane or other protein binding. This is done by injecting a sample compound into a cell or organelle, and watching the compound to bind to the membrane. The concentration of the compound in the cell or the organelle at any time can be determined. Measurement of unbound concentrations of a compound is also a part of pharmacology.
Pharmacokinetics and pharmacodynamics are related because the research studies that support one form of study often compared the outcomes of other forms of experimentation. One example would be to compare the absorption, metabolism, clearance, and toxicity between Lipitor, Celebrex, and Xolair. Although each drug had distinct characteristics of absorption, elimination, and toxicity, they all exhibited similar pharmacokinetic properties. Also, they all exhibited the same pharmacodynamic efficacy.
Because pharmacokinetics is basically the measurement of potency, the efficiency of a compound drug is also directly related to its potency. A highly potent substance is one that displays little, if any, change in effectiveness when administered. Conversely, a very weak substance is one that dramatically changes in effectiveness upon delivery. Commonly used pharmacokinetic agents are lipid solvents, such as lipase, hydrazine sulfate, and hydroxymethane. Other agents commonly used in pharmacokinetic studies are inhibitors of the cytochrome P-dependent oxidation chain, substrates, inhibitors of the transmembrane regulatory network, and drugs with metabolic inhibitors.
The key difference between pharmacokinetics and pharmacodynamics is exposure to a medicinal agent. Pharmacokinetics studies the rate of absorption and metabolism at concentrations within the physiological range of tissues. Pharmacodynamics studies the effects of exposure to a compound at various concentrations in different organ systems. Thus, the key difference between the two is exposure to drugs, rather than concentration or duration of exposure.
In most cases, pharmacokinetics and pharmacodynamics studies are performed on humans. Some types of research require animal models in addition to humans for pharmacologic effects. Pharmacokinetics studies the absorption of a large molecule like cholesterol or triglyceride in a test animal. Once the concentration of the large molecule has been determined, then the corresponding concentration of the small molecule will be determined in the test animal.
Pharmacokinetics vs. Pharmacodynamics are a useful guide to understanding and designing medication. By using both pharmacokinetics and pharmacodynamics, a medical professional will have a much better understanding of the effects of drugs on the body and how the drug concentration may vary throughout the course of a patient’s treatment. Understanding these relationships can help prevent the occurrence of harmful drug interactions, reduce the frequency of allergic reactions and decrease the development of tolerance. This information is important for all patients, but particularly important for people who take medications on a regular basis.