Pharmacokinetics is dedicated to understanding the movement of the drug. A drug once administered is absorbed, distributed, metabolized, and excreted. ADME in pharmacology and pharmacokinetics is Absorption, Metabolism, and Excretion of a drug or pharmaceutical compound within a living organism.
The four processes are necessary to measure the drug’s behaviour inside the human body and to establish its pharmacological effect on the body.
Factors Affecting ADME
The ADME properties are essential to identify and eliminate the drug candidates that do not have the potential to become a viable drug product. Hence, ADME assays and tests are conducted by scientists and experts at well-equipped laboratories to get accurate and reliable bioanalytical results. Thus, it becomes necessary to understand the various factors affecting the ADME pharmacokinetics
Different criteria affect the ADME of a drug, but here we highlight the three most important ones.
The solubility of the Drug Candidate
The drug candidate’s solubility determines the absorption and its viability to become a drug product in the future.
- Water solubility: Since the body is made of 70% water, experts are looking for drug candidates that are easily absorbed by the bodily fluids for distribution to the affected area. An increase or decrease in polarity, crystal formation, and the melting point of the drug impact the pharmacokinetic test.
- Fat – solubility: Cell membranes are a double lipid layer structure, and thus, only lipid-soluble drugs can penetrate the cell membrane. The introduction of fat-soluble compounds and side chains into the chemical composition of drugs can improve their lipid solubility. This step makes these drug compounds easy to absorb by the cell and increases the drug’s bioavailability.
Chemical Properties of the Drug Candidate
Each drug candidate or compound has chemical properties, and these properties have a direct impact on reactions with the acidic and alkaline elements inside the cell.
- Dissociation degree: It’s been scientifically proven that the higher the dissociation, the worse is the absorption. The degree of dissociation is related to the drug constant and the pH of the absorption site. For example, the stomach is the site for the absorption of weak acidic drugs, and intestine is the site for the absorption of the weak alkaline drug. On the other hand, for cell membranes, it takes longer to absorb as well as excrete strongly acidic, alkaline, and ionic drug compounds.
- Molecular weight: The kinetics and absorption of the drug inside the body are directly dependent on its molecular weight.
Biological Factors of the Patient
The biological age of cell and age of the living organism also have a direct impact on ADME pharmacokinetics.
- Age: Age of the cells is a factor that experts must consider while conducting ADME assays. Absorption and metabolism capabilities of a new cell will largely differ from a cell nearing apoptosis. Hence, the chemical formulation of the final drug product will vary for people of different age groups.
- Sex: Men and women are biologically different from each other, and hence, there is a stark difference in the ADME behavior of a drug candidate. The ADME processes for both sexes vary, and scientists have to test the effect of the drug candidate on the hormonal balance for males and females separately.