Editing Tacrolimus (section)

===Pharmacokinetics===
Oral tacrolimus is slowly absorbed in the [[gastrointestinal tract]], with a total [[bioavailability]] of 20 to 25% (but with variations from 5 to 67%) and [[Cmax (pharmacology)|highest blood plasma concentrations]] (C<sub>max</sub>) reached after one to three hours. Taking the drug together with a meal, especially one rich in fat, slows down resorption and reduces bioavailability. In the blood, tacrolimus is mainly bound to [[erythrocyte]]s; only 5% are found in the [[blood plasma|plasma]], of which more than 98.8% are bound to [[plasma protein]]s.<ref name="AC" /><ref name="Dinnendahl">{{cite book|title=Arzneistoff-Profile|editor1=Dinnendahl, V |editor2=Fricke, U |publisher=Govi Pharmazeutischer Verlag|location=Eschborn, Germany|date=2003|edition=18|volume=9|isbn=978-3-7741-9846-3|language=de}}</ref>

The substance is metabolized in the liver, mainly via [[CYP3A]], and in the intestinal wall. All [[metabolite]]s found in the circulation are inactive. [[Biological half-life]] varies widely and seems to be higher for healthy persons (43 hours on average) than for patients with liver transplants (12 hours) or kidney transplants (16 hours), due to differences in [[clearance (pharmacology)|clearance]]. Tacrolimus is predominantly eliminated via the faeces in form of its metabolites.<ref name="AC" /><ref name="Dinnendahl" />

When applied locally on eczema, tacrolimus has little to no bioavailability.<ref name="AC" />