Allopurinol: Effects, Uses & Risks

Allopurinol has proven effective for the treatment and prophylaxis of elevated uric acid levels and their sequelae. The well-tolerated drug has long been part of standard treatment.

What is allopurinol?

Allopurinol is a urostatic agent used to treat hyperuricemia and chronic gout. Allopurinol is a urostatic agent used to treat hyperuricemia and chronic gout. It is available in pharmacies under various trade names and their generics. The prescription drug is offered as tablets of 50 or 100 each containing 100 mg, and 20, 50, or 100 each containing 300 mg of its active ingredient. The drug is recommended for elevated uric acid levels of 8.5 mg/100 ml or more in adult blood serum when dietary attempts to lower it are unsuccessful or when another condition is the cause. In addition to reducing uric acid, allopurinol relieves the unpleasant symptoms of gout. It is suitable for long-term treatment under constant medical supervision. In children, allopurinol is indicated in doses less than 300 mg for conditions such as leukemia or a congenital enzyme deficiency such as Lesh-Nyhan syndrome.

Pharmacologic Action

Allopurinol carries its active ingredient in its name. It belongs to the group of gout medications. Treatment with allopurinol is intended to lower elevated uric acid levels in the blood serum. If this is successful, the pain associated with acute gout attacks is also reduced. Further gout attacks are prevented. The exact mode of action is based on the breakdown of purines, mainly organic compounds found in proteins. The human body usually breaks down purines into uric acid and excretes them through the kidneys. Allopurinol prevents this purine breakdown by inhibiting the enzyme xanthine oxidase, which is important for this purpose. While uric acid is poorly soluble in water, more of its precursor hypoxanthine is formed instead when allopurinol is administered to reduce uric acid. Unlike uric acid, hypoxanthine is highly water-soluble. This results in a desirable decrease in the elevated uric acid concentration in the blood (hyperuricemia). In the tissues, there is a breakdown of deposited urate crystals that cause typical gout symptoms, as well as their delayed reformation. Unlike uric acid, hypoxanthine can be easily excreted by the body in the urine through the kidneys. Allopurinol was shown to limit the formation of new purines in some patients, in addition to purine breakdown. Nevertheless, in renal insufficiency, allopurinol administration must be adjusted to the reduced renal capacity. In acute gout attacks, allopurinol should not be administered because it affects the solubility of uric acid. Uric acid crystals may form, which may increase or prolong the gout attack.

Medical use and application

Allopurinol has been shown to be effective for treating adults and children and is generally well tolerated. It helps lower elevated uric acid levels in the blood of more than 8.5 mg/dl, which occur primarily in hyperuricemia and gout. If a change in diet does not bring any improvement, allopurinol is recommended, even for long-term treatment. It is also excellent for preventing acute gout attacks with their painful accompanying symptoms. Other areas of application are the prevention of kidney stones and consequent damage to kidney tissue at a later stage. Children can suffer kidney damage during leukemia treatment, since the breakdown of tumor cells is accompanied by increased production of purines. Allopurinol given prophylactically counteracts the negative processes triggered by this. Allopurinol is also frequently prescribed for congenital hereditary diseases such as Lesch-Nyhan syndrome, which leads to gout even in children, or for a deficiency of adenosine phosphoribosyl transferase. Important to know: With initial treatment with allopurinol, noticeable success usually takes a long time, as it can take up to six months for uric acid deposits in the tissues to break down. Furthermore, allopurinol therapy should be started gradually.

Risks and side effects

Even a proven drug like allopurinol has risks and side effects. Allergic reactions, especially of the skin, as well as headache, dizziness, lightheadedness, nausea, and vomiting, may occur, as well as blood formation disorders, lymph node swelling, kidney stones, liver damage, and neuropathy.Allopurinol is contraindicated or should be used with increased caution in the case of already impaired kidney or liver function and certain disorders of blood formation. It should also not be given during an acute attack of gout. Allopurinol may impair driving and machine operation. Little experience is available on its use during pregnancy and lactation. As a precaution, use during these periods is not recommended.