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Encyclopedia > Prodrug

A prodrug is a pharmacological substance (drug) which is administered in an inactive (or significantly less active) form. Once administered, the prodrug is metabolised in the body in vivo into the active compound. 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. ... Oral medication A medication is a licenced drug taken to cure or reduce symptoms of an illness or medical condition. ... Metabolism (from Greek μεταβολισμός metabolismos) is the biochemical modification of chemical compounds in living organisms and cells. ... In vivo (Latin for (with)in the living). ...


Rationale

The rationale behind the use of a prodrug is generally for ADME optimization. Prodrugs are usually designed to improve oral bioavailability - poor absorption from the gastrointestinal tract is usually the limiting factor, and is often due to the chemical properties of the drug. ADME is an acronym in pharmacokinetics and pharmacology for Absorption, Distribution, Metabolism, and Excretion, and describes the disposition of a pharmaceutical compound within an organism. ... 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. ... The gastrointestinal tract or digestive tract, also referred to as the GI tract or the alimentary canal, (nourishment canal) or the gut, is the system of organs within multicellular animals which takes in food, digests it to extract energy and nutrients, and expels the remaining waste. ... A chemical substance is any material substance used in or obtained by a process in chemistry: A chemical compound is a substance consisting of two or more chemical elements that are chemically combined in fixed proportions. ...


Equally, the use of a prodrug strategy increases the selectivity of the drug for its intended target. An example of this can be seen in many anti-cancer treatments, in which the reduction of adverse effects is always of paramount importance. Drugs used to target hypoxic cancer cells, through the use of redox-activation, utilise the large quantities of reductase enzyme present in the hypoxic cell to convert the drug into its cytotoxic form, essentially activating it. As the prodrug has low cytotoxicity prior to this activation, there is a markedly lower chance of it "attacking" healthy, non-cancerous cells which reduces the side-effects associated with these chemotherapeutic agents Hypoxia is a pathological condition in which the body as a whole (generalised hypoxia) or region of the body (tissue hypoxia) is deprived of adequate oxygen supply. ... When normal cells are damaged or old they undergo apoptosis; cancer cells, however, avoid apoptosis. ... Semi-accurate illustration of a redox reaction Redox reactions include all chemical processes in which atoms have their oxidation number (oxidation state) changed. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... Chemotherapy is the use of chemical substances to treat disease. ...


In rational drug design, the knowledge of chemical properties likely to improve absorption and the major metabolic pathways in the body allows the modification of the structure of new chemical entities for improved bioavailability. However, sometimes the use of a prodrug is unintentional, especially in the case of serendipitous drug discoveries, and the drug is only identified as a prodrug after extensive drug metabolism studies. Drug design is the approach of finding drugs by design, based on what the drug is targeting. ... Look up Serendipity in Wiktionary, the free dictionary For other uses, see Serendipity (disambiguation). ...


Prodrugs also occur naturally.


Selected examples


  Results from FactBites:
 
Prodrug - definition from Biology-Online.org (129 words)
A compound that is converted within the body into its active form that has medical effects.
prodrugs useful when the active drug may be too toxic to administer ter systemically, the active drug is absorbed poorly by the digestive tract, or the body breaks down the active drug before it reaches its target.
This page was last modified 06:56, 22 August 2006.
Targeted Prodrug Design to Optimize Drug Delivery (4711 words)
In the prodrug approach, site-specific drug delivery can be obtained from tissue-specific activation of a prodrug, which is the result of metabolism by an enzyme that is either unique for the tissue or present at a higher concentration (compared with other tissues); thus, it activates the prodrug more efficiently.
Of these glycosidic prodrugs, the dexamethasone glucoside appeared to be the better candidate, with nearly 60% of the orally administered prodrugs reaching the caecum as a free steroid, while orally administered parent steroids were absorbed almost exclusively from the small intestine.
Carrier-mediated intestinal absorption of valacyclovir, the L-valyl ester prodrug of acyclovir: 1.
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