The initial oral dosage recommendations for pediatric patients with liver transplants along with recommendations for whole blood trough concentrations are shown in Table 3. For blood concentration monitoring details see Dosage and Administration ( 2.6). If necessary, pediatric patients may start on an IV dose of 0.03 to 0.05 mg/kg/day.
|Patient Population|| |
Recommended Tacrolimus Capsules Initial Oral Dosage
|Observed Tacrolimus Whole Blood Trough Concentrations|
|Pediatric liver transplant patients||0.15 to 0.20 mg/kg/day||Month 1 to 12: 5 to 20 ng/mL|
Pediatric liver transplantation patients without pre-existing renal or hepatic dysfunction have required and tolerated higher doses than adults to achieve similar blood concentrations.
Experience in pediatric kidney and heart transplantation patients is limited.
Due to its potential for nephrotoxicity, consideration should be given to dosing tacrolimus capsules at the lower end of the therapeutic dosing range in patients who have received a liver or heart transplant and have pre-existing renal impairment. Further reductions in dose below the targeted range may be required.
In kidney transplant patients with post-operative oliguria, the initial dose of tacrolimus capsules should be administered no sooner than 6 hours and within 24 hours of transplantation, but may be delayed until renal function shows evidence of recovery.
Due to the reduced clearance and prolonged half-life, patients with severe hepatic impairment (Child Pugh ≥ 10) may require lower doses of tacrolimus capsules. Close monitoring of blood concentrations is warranted.
The use of tacrolimus capsules in liver transplant recipients experiencing post-transplant hepatic impairment may be associated with increased risk of developing renal insufficiency related to high whole-blood concentrations of tacrolimus. These patients should be monitored closely and dosage adjustments should be considered. Some evidence suggests that lower doses should be used in these patients [see Dosage and Administration ( 2.1), Use in Specific Populations ( 8.7) and Clinical Pharmacology ( 12.3)].
It is recommended that patients initiate oral therapy with tacrolimus capsules if possible.
Initial dosage and observed tacrolimus whole blood trough concentrations for adults are shown in Table 1 and for pediatrics in Table 3[see Dosage and Administration ( 2.1, 2.2)] ; for blood concentration monitoring details in kidney transplant patients [see Dosage and Administration ( 2.1)].
It is important to take tacrolimus capsules consistently every day either with or without food because the presence and composition of food decreases the bioavailability of tacrolimus capsules [see Clinical Pharmacology ( 12.3)].
Tacrolimus capsules should not be used simultaneously with cyclosporine. Tacrolimus capsules or cyclosporine should be discontinued at least 24 hours before initiating the other. In the presence of elevated tacrolimus capsules or cyclosporine concentrations, dosing with the other drug usually should be further delayed.
In patients unable to take oral tacrolimus capsules, therapy may be initiated with tacrolimus injection as a continuous IV infusion. If IV therapy is necessary, conversion from IV to oral tacrolimus is recommended as soon as oral therapy can be tolerated. This usually occurs within 2 to 3 days. In patients receiving an IV infusion, the first dose of oral therapy should be given 8 to 12 hours after discontinuing the IV infusion.
Monitoring of tacrolimus blood concentrations in conjunction with other laboratory and clinical parameters is considered an essential aid to patient management for the evaluation of rejection, toxicity, dose adjustments and compliance. Observed whole blood trough concentrations can be found in Table 1. Factors influencing frequency of monitoring include but are not limited to hepatic or renal dysfunction, the addition or discontinuation of potentially interacting drugs and the post-transplant time. Blood concentration monitoring is not a replacement for renal and liver function monitoring and tissue biopsies. Data from clinical trials show that tacrolimus whole blood concentrations were most variable during the first week post-transplantation.
The relative risks of toxicity and efficacy failure are related to tacrolimus whole blood trough concentrations. Therefore, monitoring of whole blood trough concentrations is recommended to assist in the clinical evaluation of toxicity and efficacy failure.
Methods commonly used for the assay of tacrolimus include high performance liquid chromatography with tandem mass spectrometric detection (HPLC/MS/MS) and immunoassays. Immunoassays may react with metabolites as well as parent compound. Therefore assay results obtained with immunoassays may have a positive bias relative to results of HPLC/MS. The bias may depend upon the specific assay and laboratory. Comparison of the concentrations in published literature to patient concentrations using the current assays must be made with detailed knowledge of the assay methods and biological matrices employed. Whole blood is the matrix of choice and specimens should be collected into tubes containing ethylene diamine tetraacetic acid (EDTA) anti-coagulant. Heparin anti-coagulation is not recommended because of the tendency to form clots on storage. Samples which are not analyzed immediately should be stored at room temperature or in a refrigerator and assayed within 7 days; see assay instructions for specifics. If samples are to be kept longer they should be deep frozen at -20° C. One study showed drug recovery > 90% for samples stored at -20° C for 6 months, with reduced recovery observed after 6 months.
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