Factors Affecting Pharmacokinetics of Drugs

Factors Affecting ADME

There are four factors that will affect the pharmacokinetic drugs test: water-solubility; fat-soluble; dissociation degree and molecular weight.

Pharmacokinetic is a quantitative study of drugs in the body absorption, distribution, metabolism and excretion of the law.  The use of mathematical principles and methods to explain the plasma concentration with time changes in a discipline.

Water is the carrier of drug transport and the body of the medium. Drugs in the absorption site must have a certain degree of water solubility in a dissolved state, so that can be absorbed. Therefore, the drug is required to have certain water solubility. Polarity (the introduction of polar groups can increase water solubility), crystal form (the impact of drug bioavailability is more and more attention), the melting point of the solubility, thus affecting the absorption of drugs, affecting bioavailability.

Cell membrane of the double lipid layer structure requires a certain lipid-soluble drugs can penetrate the cell membrane. Come in (some fat-soluble), get out (some water-soluble).  Dissolve easily dissociable groups such as carboxyl groups. Through the modification of chemical structure, the introduction of fat-soluble groups or side chains, can improve the drug fat-soluble, promote drug absorption and improve bioavailability.

Drugs can only pass through biofilm in molecular form. Biofilm itself with a charge, phase suction, into the come, get out; reprimand: not come. Ions with hydration, the drug molecule volume increases, cannot pass through the biofilm microspores. The greater the dissociation is, the worse the absorption.

The degree of dissociation is related to the dissociation constant of the drug and the pH of the absorption site. The dissociation degree of the same drug in different parts is different and the degree of absorption is different. Weak acid drug dissociation in the stomach is small, easy to be absorbed; in the intestine, weak alkaline drug dissociation is small, so it is the weak alkaline drug absorption site.

Strong acid and alkali drugs and ionic drugs are difficult to absorb, as well as difficult to come out after entering the cell.

Excretion is the process of drug excreted from the body. The kidneys are the main organs of drug excretion. Protracted by the kidneys excreted drugs in the renal tubules can be reabsorption, so that the role of drug extension. Re-absorption by the urine pH effect, the application of acidic or alkaline drugs, changes the pH of the urine, can reduce renal tubular reabsorption of drugs.

Medicilon’s pharmacokinetics department offers the clients a broad spectrum of high quality of services in the areas of in vitro ADME. With SPF animal laboratory, Medicilon can provide you, such as mice, rats, rabbits and other different species of animal pharmacokinetics experiments and the route of administration and the way is also a variety of intravenous, gavage, subcutaneous and abdominal wait.