Allopurinol (Zyloprim)
Purpose of Medication and Method of Action
Allopurinol is indicated for the treatment of the elevation of blood uric acid. Elevated blood uric acid can lead to both gout and the formation of uric acid kidney stones. Allopurinol acts by inhibiting the enzyme xanthine oxidase which is the enzyme responsible for producing uric acid in the body.
Side Effects
Allopurinol is generally well tolerated. The most common reactions are that of an allergic nature and most commonly manifest on the skin as an itchy, eruption characterized by the appearance of small bumps and redness of that area where the bumps appear. This reaction can occur months therapy has been started and requires the drug to be stopped immediately. Rarely a fever may be the only indication of an allergic reaction. Other side effects such as headache, drowsiness, nausea and diarrhea occur occasionally but usually do not require discontinuation of the medication.
Drug Interactions
Allopurinol may increase the pharmacology and side effects of azathioprine (Immuran) and oral anticoagulants of the warfarin type. Allopurinol added to existing therapy will increase blood levels and side effects of theophylline. There have been limited reports of an increased incidence on rash when amoxicillin is added to existing Allopurinol therapy.
Cautions and Contraindications
Attacks of acute gout may occur more frequently during the initial months of Allopurinol therapy.
Usual Dose
Initially, 100 mg daily increasing to a maximum of 800 mg. Doses greater then 300 mg daily should be given in divided doses. Fluid intake should be as much as possible.
Patient Medication Information
These information sheets do not list all known side effects of the medications, only the most common side effects. For a complete list of side effects please contact your local pharmacy or the actual drug manufacturing company.