ADME is an acronym in pharmacokinetics and pharmacology for Absorption, Distribution, Metabolism, and Excretion, and describes the disposition of a pharmaceutical compound within an animal or human body. The four criteria all influence the drug levels and kinetics of drug exposure to the tissues and hence influence the performance and pharmacological activity of the compound as a drug: It has been suggested that this article or section be merged with Backronym and Apronym (Discuss) Acronyms and initialisms are abbreviations, such as NATO, laser, and ABC, written as the initial letter or letters of words, and pronounced on the basis of this abbreviated written form. ... Pharmacokinetics is a branch of pharmacology dedicated to the study of the time course of substances and their relationship with an organism or system. ... Pharmacology (in Greek: pharmacon (φάρμακον) meaning drug, and logos (λόγος) meaning science) is the study of how substances interact with living organisms to produce a change in function. ... Pharmacology (in Greek: pharmacon is drug, and logos is science) is the study of how chemical substances interfere with living systems. ... A chemical compound is a chemical substance consisting of two or more different chemically bonded chemical elements, with a fixed ratio determining the composition. ... Kinetics refers to two different areas of science: Chemical kinetics studies reaction rates. ... It has been suggested that this article or section be merged with Bioactivity. ... Oral medication A medication is a licenced drug taken to cure or reduce symptoms of an illness or medical condition. ...

Absorption 

To exert a pharmacological effect in tissues drug molecules have to pass through biological membranes such as the intestinal mucusa to get into the bloodstream. Factors such as poor compound solubility, chemical instability in the stomach, and inability to permeate the intestinal wall can all reduce the extent to which a drug is absorbed after oral administration. Oral route is the most clinically acceptable route of administration of drugs.

Distribution 

Once the drug enters the bloodstream it needs to be carried to its effector site. The compound will them distribute into various tissues and organs to differing extents based mainly on the lipophilicity of the drug. Biological barriers such as the blood-brain-barrier and transporters play a role in determining the distribution of the drug. The distribution of the drug into target organs is critical in ensuring efficacy.

Metabolism 

Drugs are typically chemicals that are not commonly found in the environment and thereby termed "xenobiotics". Several enzyme systems have evolved as man evolved that prevent exposure of humans to xenobiotics. These enzyme systems prevent exposure by chemically modifying the drug molecule mainly by oxidation (Phase I), hydrolysis, reduction or by conjugation with biologically occuring molecules by enzymes such as UDP-Glucuronyl transferase, sulfotransferase(Phase II). The main purpose of metabolism is to convert molecules to become more polar so that they can be easily excreted. The products of metabolism are called metabolites. Cytochrome P450 or CYP450 which is a heme containing oxidizing enzyme system mainly found in the liver is responsible for the metabolism of a majority of small-molecules. In most cases metabolism inactivates the pharmacological response of the drug; however in some cases metabolites can be pharmacologically active as well. Liver is the main metabolizing organ in the body; however metabolism can occur at many tissues in the body including intestine, blood and organs.

Excretion 

The process of removal of the drug and metabolites from the human body is termed "excretion". Intact drug and metabolites can be excreted by the kidneys (urine) or feces (through bile). While urinary and fecal route of elimination are the most important ones, excretion can also occur through breath, sweat and saliva.

bioavailability(F), which is the percent of drug that reaches the systemic circulation is effected by absorption and first-pass metabolism. First-pass is the metabolism that the drug undergoes prior to reaching the systemic circulation by the intestine and liver. Biopharmaceutics is the study of the release characteristics and permeability of the drug through intestinal membrane barriers. In pharmacology (and more specifically pharmacokinetics), absorption is the movement of a drug into the bloodstream. ... Red blood cells (erythrocytes) are present in the blood and help carry oxygen to the rest of the cells in the body Blood is a circulating tissue composed of fluid plasma and cells (red blood cells, white blood cells, platelets). ... Distribution in pharmacology is a branch of pharmacokinetics describing reversible transfer of drug from one location to another within the body. ... Overview of the citric acid cycle The citric acid cycle, one of the central metabolic pathways in aerobic organisms. ... Cytochrome P450 Oxidase (CYP2E1) Cytochrome P450 oxidase (commonly abbreviated CYP) is a generic term for a large number of related, but distinct, oxidative enzymes (EC 1. ... Excretion is the process of eliminating waste products of metabolism and other materials that are of no use. ... In pharmacology, bioavailability is used to describe the fraction of an administered dose of medication that reaches the systemic circulation, one of the principal pharmacokinetic properties of drugs. ...

See also

• Pharmacokinetics
• Cheminformatics
• Combinatorial chemistry
• Pharmacology
• Solubility
• Serum
• Lipinski's Rule of Five
• Bioavailability
• Caco-2

Pharmacokinetics is a branch of pharmacology dedicated to the study of the time course of substances and their relationship with an organism or system. ... Cheminformatics (also known as chemoinformatics and chemical informatics) is the use of computer and informational techniques, applied to a range of problems in the field of chemistry. ... Combinatorial chemistry involves the rapid synthesis and/or the computer simulation of a large number of different but structurally related molecules. ... Pharmacology (in Greek: pharmacon (φάρμακον) meaning drug, and logos (λόγος) meaning science) is the study of how substances interact with living organisms to produce a change in function. ... It has been suggested that Solid solubility be merged into this article or section. ... Blood plasma is the liquid component of blood, in which the blood cells are suspended. ... In 1997 Christopher A. Lipinski published a seminal paper identifying a series of features commonly found in orally active drugs. ... In pharmacology, bioavailability is used to describe the fraction of an administered dose of medication that reaches the systemic circulation, one of the principal pharmacokinetic properties of drugs. ... Caco-2 cell monolayer absorption model Cell-based functional assays, such as the Caco-2 drug transport model for assessing intestinal transport, are extremely valuable for screening lead compounds in drug discovery. ...

References

• Balani SK, Miwa GT, Gan LS, Wu JT, Lee FW., Strategy of utilizing in vitro and in vivo ADME tools for lead optimization and drug candidate selection, Curr Top Med Chem. 2005;5(11):1033-8.
• Singh SS., Preclinical pharmacokinetics: an approach towards safer and efficacious drugs, Curr Drug Metab. 2006 Feb;7(2):165-82.
• Tetko IV, Bruneau P, Mewes HW, Rohrer DC, Poda GI., Can we estimate the accuracy of ADME-Tox predictions?, Drug Discov Today. 2006 Aug;11(15-16):700-7, pre-print.

External links

• The Emerging Role of A.D.M.E. in Optimizing Drug Discovery and Design