Products
Allopurinol is in the form of tablets trade (Zyloric, generic). It is approved in many countries since the year 1966. Allopurinol is also combined with the URAT1 inhibitor lesinurad.
Structure and properties
Allopurinol (C5H4N4O, Mr = 136.1 g/mol) exists as a white powder that is very sparingly soluble in water. It is a derivative of the natural purine base hypoxanthine. The active metabolite oxipurinol has a much longer half-life and is substantially involved in its effects.
Effects
Allopurinol (ATC M04AA01) has uricostatic properties. The effects are due to inhibition of the enzyme xanthine oxidase, which inhibits the formation of uric acid from xanthine (an intermediate in purine metabolism). This leads to lowering of uric acid concentration in blood and urine.
Indications
To prevent the formation of urates and uric acid, for example in gout, kidney stones, cancer, and chemotherapy. For the treatment of kidney stones.
Dosage
According to the drug label. The tablets are usually taken once a day after a meal.
Contraindications
- Hypersensitivity
For complete precautions, see the drug label.
Interactions
Numerous drug-drug interactions are known with allopurinol, for example, with diuretics, ACE inhibitors, penicillins, and ciclosporin. Azathioprine is metabolized to 6-mercaptopurine, which is inactivated by xanthine oxidase. When combined with allopurinol, the dose must be reduced because the breakdown of 6-mercaptopurine is decreased.
Adverse effects
The most common possible adverse effects include nausea, vomiting, and skin reactions. If skin rashes occur, contact your healthcare provider because they can be serious (e.g., Stevens-Johnson syndrome, toxic epidermal necrolysis).
