The present invention provides a complex of a drug, hormone, bio-active peptide, or immunoger with the carrier molecule vitamin B12 and a method for delivering said complex to the intestine of a host vertebrate in order to deliver the complex to the circulation of the host and thereby elicit a pharmacological response to the drug, hormone, or bio- active molecule orto elicit a systemic immune response to the immunogen. The invention also provides a method for the production of the complex. Further the invention provides medicaments containing the complex.