reated with Envarsus. The event rate of biopsy-confirmed acute rejection within the 360 day study period was not significantly different between the Envarsus group and the tacrolimus immediate-release group. The overall incidence of fatal treatment emergent adverse events for the combined de novo and stable liver transplant population was not significantly different between the Envarsus group and the tacrolimus immediate-release group
5.2 Pharmacokinetic properties
Absorption
The oral bioavailability of Envarsus was decreased when the product was administered after a meal; the extent of absorption was decreased by 55% and the maximum plasma concentration was decreased by 22% when taken directly after a high-fat meal. Therefore, Envarsus should generally be taken on an empty stomach to achieve maximal absorption.
In man tacrolimus has been shown to be able to be absorbed throughout the gastrointestinal tract. Available tacrolimus is generally rapidly absorbed. Envarsus is a prolonged-release formulation of tacrolimus resulting in an extended oral absorption profile with an average time to maximum blood concentration (Cmax) of approximately 6 hours (tmax) at steady state.
Absorption is variable and the mean oral bioavailability of tacrolimus is in the range of 20%-25% (individual range in adult patients 6%-43%). The oral bioavailability is approximately 40% higher for Envarsus as compared to the same dose of tacrolimus immediate-release formulation (Prograf) in kidney transplant patients.
Higher Cavg (~50%), reduced peak trough fluctuation (Cmax/Cmin) and a longer Tmax were seen for Envarsus when compared with both, tacrolimus immediate-release formulation (Prograf) and a tacrolimus once daily formulation (Advagraf). Mean values for Cmax, percentage degree of fluctuation and percentage degree of swing were significantly lower with administration of Envarsus tablets.
A strong correlation exists between AUC and whole blood trough levels at steady-state for Envarsus. Monitoring of whole blood trough levels therefore provides a good estimate of systemic exposure.
In vitro test results indicate that there is no risk of in vivo dose dumping related to alcohol intake.
Distribution
In man, the disposition of tacrolimus after intravenous infusion may be described as biphasic.
In the systemic circulation, tacrolimus binds strongly to erythrocytes resulting in an approximate 20:1 distribution ratio of whole blood/plasma concentrations. In plasma, tacrolimus is highly bound (>98.8%) to plasma proteins, mainly to serum albumin and α-1-acid glycoprotein.
Tacrolimus is extensively distributed in the body. The steady-state volume of distribution based on plasma concentrations is approximately 1,300 L (healthy subjects). Corresponding data based on whole blood averaged 47.6 L.
Biotransformation
Tacrolimus is widely metabolised in the liver, primarily by the cytochrome P450-3A4. Tacrolimus is also considerably metabolised in the intestinal wall. There are several metabolites identified. Only one of these has been shown in vitro to have immunosuppressive activity similar to that of tacrolimus. The other metabolites have only weak or no immunosuppressive activity. In systemic circulation only one of the inactive metabolites is present at low concentrations. Therefore, metabolites do not contribute to the pharmacological activity of tacrolimus.
Elimination
Tacrolimus is a low-clearance |
