Interferon alfa is poorly absorbed after oral administration due to
its degradation by proteolytic enzymes and studies have not detected
measurable levels in the systemic circulation, however,
there may
be some absorption via upper GI mucosa.
Interferon alfa is widely distributed throughout the body, although
it does not penetrate into the CNS well. It is unknown if
it crosses the placenta. Interferon alfa is freely filtered by the glomeruli,
but is absorbed by the renal tubules where it is metabolized by
brush border or lysosomes. Hepatic metabolism is of minor importance.
The plasma half-life in cats has been reported as 2.9 hours.