Gout is frequently a troublesome complication in renal transplant recipients, the investigators pointed out. Patients already receiving azathioprine for immunosuppression are frequently denied definitive treatment with allopurinol because of the potentially life-threatening interaction between the two agents, they explained.
Natalie Borman, MBBCh, MRCP, and collaborators at Portsmouth Hospitals NHS Trust in Portsmouth, Hampshire, U.K., identified 12 renal transplant recipients who received allopurinol in addition to azathioprine at a 75% reduced dose. All subjects had suffered from two or more gout attacks in the preceding six months. The mean interval between transplantation and the start of allopurinol treatment was 113 months. Patients received a constant dose of a calcineurin inhibitor for additional immunosuppression.
The mean introductory dose of allopurinol was 187.5 mg/day based on a clinical judgment. The treatment was highly effective in preventing gout relapses, with a mean 36% reduction in uric acid (from 0.63 mmol/L before allopurinol treatment to 0.40 mmol/L after treatment), the researchers reported at the World Congress of Nephrology. One patient withdrew from the study because of a reduction in white cell count. Allopurinol was later reintroduced with an additional 50% decrease in azathioprine dose and the treatment was tolerated. Another patient briefly stopped azathioprine because of a reduction in white cell count but remained on allopurinol, the researchers related. Azathioprine was reintroduced three weeks later at half the dose and it was tolerated. Overall, white cell counts, hemoglobin levels, and serum creatinine levels remained unchanged.
With appropriate monitoring and dose adjustment, the combined use of allopurinol and azathioprine is safe and effective in renal transplant recipients suffering from recurrent gout, Dr. Borman’s group concluded. They recommended that the azathioprine dose be reduced by 75% prior to the introduction of allopurinol. Although allopurinol was started at variable doses in the study, the researchers recommended that the drug be started at a dose of 100 mg/day and titrated up as appropriate.