Data source: http://en.wikipedia.org/wiki/Allopurinol
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.
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. 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
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
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
Toxic Epidermal Necrolysis Syndrome (TENS) which is an adverse
Allopurinol is marketed by Prometheus in the United States as Zyloprim, while in
other countries it continues to be marketed by GlaxoSmithKline.
Other brand names are Allohexal, Allosig, Progout, and Zyloric.