Sirolimus tolerability in a kidney transplant recipient with acute intermittent porphyria

Sir, Acute intermittent porphyria (AIP) is transmitted as autosomal dominant disorder with incomplete penetrance. It results from a deficiency of the porphobilinogen deaminase enzyme of haeme biosynthesis. Clinical manifestations of acute attacks include abdominal pain, hypertension and neuro-psychiatric dysfunction, and are often triggered by exposure to exogenous precipitating factors, such as drugs w1x. In porphyric patients, drug treatment should be prescribed only after reference to a drug list that considers safe and unsafe medications. For a long time, only steroids and azathioprine were considered to be safe in porphyric patients undergoing organ transplantation. Recently mycophenolate mofetil and calcineurin inhibitors (cyclosporin and tacrolimus) were reported to be safe in one kidney transplant recipient with AIP w2x. However, nephrotoxicity represents the principal side-effect of calcineurin inhibitors w3x. Sirolimus is a new potent immunosuppressant, which does not share the nephrotoxicity of calcineurin inhibitors and could facilitate recovery from delayed graft function w3,4x. We report for the first time the use of sirolimus in a kidney transplant recipient with AIP.