Intraperitoneal administration (i.e. in the abdomen) is not a physiological route.

The administration route of a drug candidate should be the same as intended in humans. In case of a protein I assume either subcutaneous (under the skin) or intravenously (normally injection via the tail vein). Intravenous administration yields rapid absorption, whereas absorption is delayed after subcutaneous administration.

Best regards

Thomas

IP and IV avoids "Oral absorption" issues when dosing. You would have to give more information as to why you are considering the route. IP can be a good method to assess the kinetics/dynamics of the drug candidates. Bioavailability would have to be assessed to be sure about how much drug can be absorbed thru this method, relative to IV.

With IP, drug is absorbed into the mesenteric blood supply that is carried directly to the liver such that it is subject to hepatic first pass metabolism; only GI lumenal metabolism/efflux is avoided.  Accordingly, systemic exposure after IP administration is typically less, and sometimes substantially less than that after IV administration if the drug is subject to FPM.

IP is a short-cut/convenience route of administration that you will ultimately end up needing to compare to IV (and to oral if that is an intended route); why not use IV in the first place and avoid the uncertainty?

With IP, drug is absorbed into the mesenteric blood supply that is carried directly to the liver such that it is subject to hepatic first pass metabolism; only GI lumenal metabolism/efflux is avoided.  Accordingly, systemic exposure after IP administration is typically less, and sometimes substantially less than that after IV administration if the drug is subject to FPM.

IP is a short-cut/convenience route of administration that you will ultimately end up needing to compare to IV (and to oral if that is an intended route); why not use IV in the first place and avoid the uncertainty?