Allopurinol
Systematic (IUPAC) name
3,5,7,8-tetrazabicyclo[4.3.0] nona-3,5,9-trien-2-one
Identifiers
CAS number	315-30-0
ATC code	M04AA01
PubChem	2094
DrugBank	APRD00435
Chemical data
Formula	C5H4N4O
Mol. mass	136.112 g/mol
Pharmacokinetic data
Bioavailability	78±20%
Protein binding	Negligible
Metabolism	hepatic (80% oxypurinol, 10% allopurinol ribosides)
Half life	2 hours (oxypurinol 18-30 hours)
Excretion	?
Therapeutic considerations
Pregnancy cat.	C(USA) Image File history File links No higher resolution available. ... IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... The Anatomical Therapeutic Chemical Classification System is used for the classification of drugs. ... A section of the Anatomical Therapeutic Chemical Classification System. ... PubChem is a database of chemical molecules. ... The DrugBank database available at the University of Alberta is a unique bioinformatics and cheminformatics resource that combines detailed drug (i. ... A chemical formula is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... For other uses, see Carbon (disambiguation). ... This article is about the chemistry of hydrogen. ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... General Name, symbol, number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, period, block 16, 2, p Appearance colorless (gas) pale blue (liquid) Standard atomic weight 15. ... The molecular mass (abbreviated Mr) of a substance, formerly also called molecular weight and abbreviated as MW, is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ... In pharmacology, bioavailability is used to describe the fraction of an administered dose of unchanged drug that reaches the systemic circulation, one of the principal pharmacokinetic properties of drugs. ... A drugs efficacy may be affected by the degree to which it binds to the proteins within blood plasma. ... Drug metabolism is the metabolism of drugs, their biochemical modification or degradation, usually through specialized enzymatic systems. ... The biological half-life of a substance is the time required for half of that substance to be removed from an organism by either a physical or a chemical process. ... The kidneys are important excretory organs in vertebrates. ... The pregnancy category of a pharmaceutical agent is an assessment of the risk of fetal injury due to the pharmaceutical, if it is used as directed by the mother during pregnancy. ...
Legal status	Schedule 6 (USA) The regulation of therapeutic goods, that is drugs and therapeutic devices, varies by jurisdiction. ...
Routes	tablet (100, 300 mg)

Allopurinol is a drug used primarily to treat conditions arising from excess uric acid, most notably chronic gout. Allopurinol does not alleviate acute attacks of gout, but is useful in preventing recurrence. Allopurinol has been used in the United States since 1964. In pharmacology and toxicology, a route of administration is the path by which a drug, fluid, poison or other substance is brought into contact with the body. ... Uric acid (or urate) is an organic compound of carbon, nitrogen, oxygen and hydrogen with the formula C5H4N4O3. ...

Mechanism of action

Allopurinol is a structural isomer of hypoxanthine (a naturally occurring purine in the body) and acts to inhibit xanthine oxidase. This enzyme is responsible for the successive oxidation of hypoxanthine and xanthine resulting in the production of uric acid, the product of human purine metabolism.^[1] In addition to blocking uric acid production, inhibition of xanthine oxidase causes an increase in hypoxanthine and xanthine, which are converted to closely related purine ribotides adenosine and guanosine monophosphates. Increased levels of these ribotides causes feedback inhibition of amidophosphoribosyl transferase, the first and rate-limiting enzyme of purine biosynthesis. Allopurinol therefore decreases both uric acid formation and purine synthesis. In chemistry, isomers are molecules with the same chemical formula and often with the same kinds of chemical bonds between atoms, but in which the atoms are arranged differently (analogous to a chemical anagram). ... Hypoxanthine is a naturally occurring purine derivative, and one of the products of the action of xanthine oxidase on xanthine, though more normally in purine degradation, hypoxanthine is oxidized by xanthine oxidase to form xanthine. ... Purine is a heterocyclic aromatic organic compound, consisting of a pyrimidine ring fused to an imidazole ring. ... HIV protease in a complex with the protease inhibitor ritonavir. ... Xanthine Oxidase The enzyme xanthine oxidase, or XO, (bovine milk enzyme is PDB 1FIQ, EC 1. ... Uric acid (or urate) is an organic compound of carbon, nitrogen, oxygen and hydrogen with the formula C5H4N4O3. ... Purine is a heterocyclic aromatic organic compound, consisting of a pyrimidine ring fused to an imidazole ring. ... Uric acid (or urate) is an organic compound of carbon, nitrogen, oxygen and hydrogen with the formula C5H4N4O3. ... Amidophosphoribosyltransferase is an enzyme which converts phosphoribosylpyrophosphate into 5-phosphoribosylamine. ... Uric acid (or urate) is an organic compound of carbon, nitrogen, oxygen and hydrogen with the formula C5H4N4O3. ... Purine is a heterocyclic aromatic organic compound, consisting of a pyrimidine ring fused to an imidazole ring. ...

Uses (other than in treatment of gout)

In addition to its use in gout, allopurinol is also commonly used as prophylaxis with chemotherapeutic treatments, which can rapidly result in very high uric acid concentrations due to widespread cell death (tumour lysis syndrome). Other established indications for allopurinol therapy include ischaemic reperfusion injury, kidney stones (urolithiasis) and protozoal infections (Leishmaniasis). Uric acid (or urate) is an organic compound of carbon, nitrogen, oxygen and hydrogen with the formula C5H4N4O3. ... “Bladder stone” redirects here. ...

Metabolism

Allopurinol is rapidly metabolized by its target, xanthine oxidase, to its active metabolite oxypurinol, which is also an inhibitor of xanthine oxidase. Allopurinol is almost completely metabolized to oxypurinol within two hours of oral administration, whereas oxypurinol is slowly excreted by the kidneys over 18-30 hours. For this reason, oxypurinol is believed to be responsible for the majority of allopurinol's effect.

Side effects

Side effects of allopurinol are rare, though significant when they occur. A small percentage of people develop a rash and must discontinue this drug. The most serious adverse effect is a hypersensitivity syndrome consisting of fever, skin rash, eosinophilia, hepatitis, worsening renal function and, in some cases, allopurinol hypersensitivity syndrome. Allopurinol is one of the drugs commonly known to cause Stevens-Johnson syndrome (SJS), and TENS (Toxic Epidermal Necrolysis Syndrome) which is an adverse drug reaction. Eosinophilia is the state of having high eosinophil granulocytes in the blood. ... Hepatitis (plural hepatitides) implies injury to liver characterised by presence of inflammatory cells in the liver tissue. ... Stevens-Johnson syndrome (SJS) is a severe and life-threatening condition. ... An adverse drug reaction (abbreviated ADR) is a term to describe the unwanted, negative consequences sometimes associated with the use of medications. ...

Brand names

Allopurinol is marketed by GlaxoSmithKline in the United States as Zyloprim. Other brand names are Allohexal, Allosig, Progout, and Zyloric. GlaxoSmithKline plc (LSE: GSK NYSE: GSK) is a British based pharmaceutical, biological, and healthcare company. ...

References