ADMET
From DrugPedia: A Wikipedia for Drug discovery
ADMET absorption, distribution, metabolism, excretion and toxicology, describes the disposition of a pharmaceutical compound within an organism. These four criterias influence the drug level and kinetics of drug exposure to the tissues and hence influence the performance and pharmacological activity of the compound as a drug.
All xenobiotics (molecules that are alien to your body) are affected by these natural processes in the human body. Absorption determines if the drug gets into the body (passing of the gastro-intestinal tract), distribution determines if the drug can arrive at the place of action, metabolism determines whether the drug is broken down before it can arrive at place of action and excretion determines whether the drug is gone before / too soon after it can become active. ADME plays an ever increasingly important role in the drug design process.
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Absorption
Drug Absorption is the process of intriducing the drug into the bloodstream.
Absorption affects bioavailability—how quickly and how much of a drug reaches its target site of action. Factors that affect absorption include:
- method of designing and manufacturing a drug
- physical and chemical properties of drug
- physiologic characteristics of the person taking the drug
Physiologic characteristics that may affect the absorption of drugs taken by mouth include
- how long the stomach takes to empty
- what the acidity (pH) of the stomach is
- how quickly the drug is moved through the digestive tract
Distribution
Drug distribution is the process of movement of a drug to and from the blood and various tissues of the body (for example, fat, muscle, and brain tissue) and the relative proportions of drug in the tissues.
After the drug is absorbed in the body it is circulated in the blood stream and moves into various body tissuses. Drug penetrates various tissuses depending on the ability to cross membranes.
Metabolism
Drug metabolism refers to the process of chemical alterations of the drug by the body.
The substances resulting from the metabolism called metabolites can be inactive or having same therapeutic activity as the drug. Prodrugs are administered in inactive form and is metabolised inside body into active metabolite. Majority of the drugs must pass through the liver which is the major site for drug metabolism.
Excretion
Drug excretion is the removal of drug from the body. Excretion is the pharmacokinetic process of getting the drug out of the body.
All drugs are eliminated from the body after the process of metabolism occurs. They are eliminated
- after being chemically altered (metabolized)
- or intact.
Most drugs, particularly water-soluble drugs and their metabolites, are eliminated largely by the kidneys in urine. Some drugs are eliminated by excretion in the bile.
Toxicology
Drug toxicology refer to the study of chemical toxicity of the drug.
various techniques are available for pursuing the toxicological studies of the drug. The insilico methods are also available like:
- QSAR-based systems can generate and validate accurate, rapid assessments of chemical toxicity solely from a chemical’s molecular structure.
- Pharmacophore-based activity profiling allows researchers to easily apply all of the accumulated knowledge from past pharmacophore models to each and every new drug discovery project.
