Neurotoxicity and Tacrolimus: Relationship with Serum Levels and Magnesium (P04.168)

Objective: To evaluate the relationship between tacrolimus serum concentrations and neurologic side-effects. Background Tacrolimus (FK) is a calcineurin inhibitor immunosuppressant with important neurotoxicity (NTX). The neurologic side-effects can be divided into two groups: minor neurotoxic effects, as tremor and headache, and major complications, as neuropathy, reversible posterior leukoencephalopathy syndrome (RPLS) and seizures. The pathophysiology of NTX is partially known. Despite not being directly related to plasma levels, major complications are more frequent with higher levels of FK. A proposed predisposing factor for NTX from FK is hypomagnesemia (HMg). Design/Methods: We retrospectively analyzed the medical records of transplant patients immunosuppressed with FK admitted to our academic center between February/04 and July/10 who had a neurological complication. Patients with NTX were divided according to the dosage of FK (in ng/ml) and Mg levels. Results: From 101 patients evaluated, sixty received FK. Thirty-six patients (60%) had neurological complications secondary to immunosuppression, but not to FK, while 24 (40%) were related to FK. We excluded 5 patients with minor neurotoxic effects from this analysis. The remaining 19 patients were divided into 3 groups according to FK plasma levels: 7 dosage FK 18 (15.7%), 2 seizures and 1 RPLS. Only five patients with HMg (26.4%) defined as values Conclusions: While there have been reports that HMg featured with FK increases neurotoxicity, this association wasn9t reflected in our analysis. We found no difference in the number of patients with NTX in relation to the dosage of FK or the type of complication, at the levels commonly used ( Disclosure: Dr. Pontello has nothing to disclose. Dr. Gonzalez Toledo has nothing to disclose. Dr. Jauregui has nothing to disclose. Dr. Munoz Giacomelli has nothing to disclose. Dr. Calle has received personal compensation for activities with UCB Pharma.