Intraperitoneal and subcutaneous pharmacokinetics of low molecular weight heparin in continuous ambulatory peritoneal dialysis patients.

Today, low molecular weight heparins (LMWHs) are more and more commonly used. They are about to replace standard heparin in certain circumstances. The pharmacokinetics of intraperitoneal standard heparin are well known in continuous ambulatory peritoneal dialysis (CAPD), but data concerning LMWHs are lacking. The present study investigated the pharmacokinetics of intraperitoneal LMWHs in a single dose and compared them with the subcutaneous route in CAPD patients. The study enrolled 8 CAPD patients with a mean age of 47 +/- 14.14 years. All patients had 40 mg enoxaparin added to their night exchange on one day. Blood samples were drawn just before instillation and at 2, 4, 8, 12, 18, and 24 hours after instillation for determination of plasma antifactor Xa activity. After two days of washout, the same patients were given enoxaparin 40 mg subcutaneously, and blood samples were drawn at the same time points. Although no plasma factor Xa activity was seen after intraperitoneal administration, subcutaneous administration resulted in increased plasma factor Xa activity. We conclude that a single dose of intraperitoneal enoxaparin did not cause any change in plasma anti-factor Xa activity. That finding may be due either to an insufficient dose or to nonabsorption.