Peritoneal-plasma barrier.

The peritoneal-plasma barrier is a pharmacologic entity of importance for treatment planning in patients with malignant tumours confined to the abdominal cavity. This physiologic barrier limits the resorption of drugs from the peritoneal cavity into the blood. The sequestration of chemotherapeutic agents improves their locoregional cytotoxicity and reduces their systemic toxicity. The physical nature of the peritoneal-plasma barrier has not been clearly defined. Further pharmacologic studies need to be performed in order to achieve a better understanding of this interesting metabolic phenomenom. At present, it is suspected that a diffusion barrier exists that consists of subserosal tissues or blood vessel walls. As postulated by Maher [29], the capillary wall appears to offer the dominant resistance to the transfer of larges solutes. The mesothelium and intersitium impede their movement to a lesser extent, and their removal during cytoreductive surgery does not affect the pharmacology of postoperative intraperitoneal chemotherapy.