Parenteral (administration)

Refers to any route of drug administration that bypasses the GI tract, i.e. the drug is not absorbed through the walls of the stomach or the intestines. As such, the blood supply that the drug is absorbed into does NOT drain immediately to the portal circulation entering the liver, meaning the drug is not subjected to first-pass metabolism. Common parenteral administration routes include intravenous, topical, sublingual and buccal, while rectal suppositories may minimise first-pass metabolism if they are inserted a short distance into the lower rectum.