Colorectal administration of human interferon -alpha

The possibility that human interferon-α may be absorbed by the colorectal mucosa has been evaluated in the rat. Suppository bases per se do not allow interferon absorption as it was undetectable in peripheral plasma. Inclusion of physiological amounts of Na-ursodeoxycholate favours some interferon absorption although plasma levels remain at a much lower level after comparative subcutaneous administration. Although the results are encouraging, we have been unable to achieve a marked increase of interferon levels in the portal blood that may render rectal administration a selective route in the treatment of hepatitis.