Michael J. Hageman

Intraperitoneal (IP) administration of drugs is a long-recognized route of administration but seldom routinely used outside of pharmacology screening in various rodent models. Hence, the scientific understanding and research investigation has received limited evaluation. The peritoneal cavity is an enclosed void in the abdominal region of mammals which encapsulates, lubricates, and facilitates fluid exchange of the abdominal organs. This cavity is lined by a complex serous membrane known as the peritoneum which provides an accessible transfer point to the blood capillaries and lymphatic system. This membrane exhibits a total surface area approximately equal to that of the surface of the skin.¹ The extensive membrane surface area combined with extensive vasculature leads to rapid absorption with more similarities to IV administration than to other administration routes such as oral or subcutaneous administration.² This drug absorption pattern as well as other advantages of this route provide unique opportunities which are largely unexplored. A brief look into the physiological aspects that lead to the peritoneum's unique absorption behavior, examples of widespread, yet poorly understood, usage in preclinical drug evaluation are concluded with description of current applications followed with a speculative look into the future of this administration route.