Case Report: Azathioprine: An Old and Wronged Immunosuppressant.

Mycophenolate rapidly substituted azathioprine (AZA) in transplant immunosuppression regimens since the 1990s, when early clinical trials indicated better outcomes, although opposite results were also observed. However, none of these trials used the well-established optimization methods for AZA dosing, namely, thiopurine methyltransferase pharmacogenetics combined with monitoring of the thiopurine metabolites 6-thioguanine nucleotides (6-TGN) and 6-methylmercaptopurine (6-MMP). Resistance to optimize AZA therapy remains today in transplant therapy, despite the fact that thiopurine metabolite testing is being used by other medical disciplines with evident improvement in clinical results. In a previous analysis, we found that active 6-TGN metabolites were not detectable in about 30% of kidney transplant patients under continuous use of apparently adequate azathioprine dosage, which demonstrates the need to monitor these metabolites for therapeutic optimization. Two of four case studies presented here exemplifies this fact. On the other hand, some patients have toxic 6-TGN levels with a theoretically appropriate dose, as seen in the other two case studies in this presentation, constituting one more important reason to monitor the AZA dose administered by its metabolites. This analysis is not intended to prove the superiority of one immunosuppressant over another, but to draw attention to a fact: there are thousands of patients around the world receiving an inadequate dose of azathioprine and, therefore, with inappropriate immunosuppression. This report is also intended to draw attention, to clinicians using thiopurines, that allopurinol co-therapy with AZA is a useful therapeutic pathway for those patients who do not adequately form active thioguanine metabolites.

Clinical features and outcomes of tuberculosis in kidney transplant recipients in Brazil: a report of the last decade.

BACKGROUND: Among kidney transplant recipients (KTRs), tuberculosis is one of the most common opportunistic infections and is associated with high morbidity and mortality. The aim of this study was to describe the incidence, clinical features, and prognosis of tuberculosis in KTRs. METHODS: Retrospective single-center observational study involving all cases of tuberculosis in KTRs between 2000 and 2010. RESULTS: Of the 1549 KTRs evaluated, 43 (2.8%) developed tuberculosis, translating to an annual incidence of 803 cases/100 000 patients, considerably higher than that reported for the general population of Brazil. The median time to tuberculosis (TB) onset after transplantation was 196 d (range, 19-3626 d). Of the KTRs with tuberculosis, 67% became infected within the first year post-transplant, 74% had pulmonary tuberculosis, and 7% had a previous history of active tuberculosis. No tuberculosis prophylaxis was employed before or after transplantation. The most common symptoms were fever (in 79%), cough (in 35%), and dyspnea (in 16%). The median time from the onset of symptoms to the start of treatment was 28 d. The median duration of antituberculosis therapy was 196 d. In 15 patients (35%), the immunosuppressive therapy was reduced, and the incidence of acute rejection was higher in patients with tuberculosis than in those without (44% vs. 28%). Mortality during tuberculosis treatment was 12% (5 cases), and all five deaths were attributed to tuberculosis. Ten-yr death-censored graft survival and patient survival were similar between patients with tuberculosis and those without. CONCLUSION: Among KTRs, symptoms of tuberculosis are often attenuated, which leads to delayed diagnosis, and tuberculosis-related mortality remains high.