Evaluation system to prevent adverse drug reaction from allopurinol in patients with chronic diseases

Abstract

Allopurinol is a drug widely used to reduce uric acid in patients with gout. An adverse reaction from the drug, allopurinol hypersensitivity syndrome (AHS), has been reported to cause severe effects to the skin and some internal organs, resulting in high morbidity and mortality. Such condition was found to be associated with high dosage prescription and the underlying chronic kidney diseases. The objective of this study was to evaluate a programme to prevent AHS. It was conducted as a prospective descriptive study from october 2009-June 2011 in Mahasarakham Hospital, Thailand. Patients with chronic diseases who required allopurinol would be monitored and routinely followed-up by a multidisciplinary team based on a guideline which was established to adjust dosage of allopurinol to fit with the renal function parameters. At the end of the study, there were 524 patients recruited. It was found that AHS was detected in 4 patients with the incidence of 0.23 per 1,000 prescriptions. The complications were found to be mild with 4 cases of level C (not harmful) and 1 case of level E (temporary and require a medication); and all incidents were associated with the consumption of high dose of the drug. The AHS patients were of older age (with mean age of 67 years old); and four of the 5 cases had concurrent renal disease and one with high blood pressure. The skin rashes were found to be maculopapular (3 cases) and erythema multiforme (2 cases). The program demonstrated a lower level of drug reaction compared to the years 2007-2008 when 3 cases (0.14 per 1,000 prescriptions) of severe AHS was observed with serious complications resulting in 2 deaths. Among the three, toxic epidermal necrolysis were found in 2 cases and Stevens-Johnson syndrome in one. Therefore, it could be concluded that the AHS prevention program was effective in preventing severe complications of adverse allopurinol reaction. Continued implementation of the approach is recommended, with particular attention on the patients with old age or kidney diseases.