Tacrolimus may cause a spectrum of neurotoxicities, particularly when used in high doses. The most severe neurotoxicities include posterior reversible encephalopathy syndrome (PRES), delirium, and coma. Patients treated with tacrolimus have been reported to develop PRES. Symptoms indicating PRES include headache, altered mental status, seizures, visual disturbances and hypertension. Diagnosis may be confirmed by radiological procedure. If PRES is suspected or diagnosed, blood pressure control should be maintained and immediate reduction of immunosuppression is advised. This syndrome is characterized by reversal of symptoms upon reduction or discontinuation of immunosuppression.
Coma and delirium, in the absence of PRES, have also been associated with high plasma concentrations of tacrolimus. Seizures have occurred in adult and pediatric patients receiving tacrolimus [see Adverse Reactions ( 6.1)] .
Less severe neurotoxicities, include tremors, paresthesias, headache, and other changes in motor function, mental status, and sensory function [see Adverse Reactions ( 6.1)] . Tremor and headache have been associated with high whole-blood concentrations of tacrolimus and may respond to dosage adjustment.
Hyperkalemia has been reported with tacrolimus use. Serum potassium levels should be monitored. Careful consideration should be given prior to use of other agents also associated with hyperkalemia (e.g., potassium-sparing diuretics, ACE inhibitors, angiotensin receptor blockers) during tacrolimus therapy [see Adverse Reactions ( 6.1)] .
Hypertension is a common adverse effect of tacrolimus therapy and may require antihypertensive therapy [see Adverse Reactions ( 6.1)] . The control of blood pressure can be accomplished with any of the common antihypertensive agents, though careful consideration should be given prior to use of antihypertensive agents associated with hyperkalemia (e.g., potassium-sparing diuretics, ACE inhibitors, angiotensin receptor blockers) [see Warnings and Precautions ( 5.9)] . Calcium-channel blocking agents may increase tacrolimus blood concentrations and therefore require dosage reduction of tacrolimus [see Drug Interactions ( 7.5)].
Anaphylactic reactions have occurred with injectables containing castor oil derivatives, including tacrolimus, in a small percentage of patients (0.6%). The exact cause of these reactions is not known. Tacrolimus injection should be reserved for patients who are unable to take tacrolimus capsules [see Indications and Usage ( 1.4)] .
Patients receiving tacrolimus injection should be under continuous observation for at least the first 30 minutes following the start of the infusion and at frequent intervals thereafter. If signs or symptoms of anaphylaxis occur, the infusion should be stopped. An aqueous solution of epinephrine should be available at the bedside as well as a source of oxygen.
The safety and efficacy of tacrolimus with sirolimus has not been established in kidney transplant patients.
Use of sirolimus with tacrolimus in studies of de novo liver transplant patients was associated with an excess mortality, graft loss, and hepatic artery thrombosis (HAT) and is not recommended [see Indications and Usage ( 1.4)] . Use of sirolimus (2 mg per day) with tacrolimus in heart transplant patients in a U.S. trial was associated with increased risk of renal function impairment, wound healing complications, and insulin-dependent post-transplant diabetes mellitus, and is not recommended [see Clinical Studies ( 14.3) ] .
When coadministering tacrolimus with strong CYP3A4-inhibitors (e.g., telaprevir, boceprevir, ritonavir, ketoconazole, itraconazole, voriconazole, clarithromycin) and strong inducers (e.g., rifampin, rifabutin) adjustments in the dosing regimen of tacrolimus and subsequent frequent monitoring of tacrolimus whole blood trough concentrations and tacrolimus associated adverse reactions are recommended [see Drug Interactions (7)] .
Tacrolimus may prolong the QT/QTc interval and may cause Torsade de Pointes. Avoid tacrolimus in patients with congenital long QT syndrome. In patients with congestive heart failure, bradyarrhythmias, those taking certain antiarrhythmic medications or other medicinal products that lead to QT prolongation, and those with electrolyte disturbances such as hypokalemia, hypocalcemia, or hypomagnesemia, consider obtaining electrocardiograms and monitoring electrolytes (magnesium, potassium, calcium) periodically during treatment.
When coadministering tacrolimus with other substrates and/or inhibitors of CYP3A4 that also have the potential to prolong the QT interval, a reduction in tacrolimus dose, frequent monitoring of tacrolimus whole blood concentrations, and monitoring for QT prolongation is recommended. Use of tacrolimus with amiodarone has been reported to result in increased tacrolimus whole blood concentrations with or without concurrent QT prolongation [see Drug Interactions (7)] .
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