Studies on liposome-encapsulated heparin.
In order to prolong the anticoagulant activity of heparin in vivo, attempts were made to encapsulate heparin into liposomes. Liposome-encapsulated heparin (lipo-heparin) prepared was large multilamellar vesicles (0.5-4.0 micron in diameter). The activity of lipo-heparin was 1.6-5.2 X 10(3) U/g lipid with recovery rate ranged between 0.4 to 1.3% and stable in saline at 4 degrees C for at least two weeks. When intravenously administered into rats, the anticoagulant activity of lipo-heparin was significantly prolonged (approximately three times), as compared with that of untreated heparin. Furthermore, the activity of lipo-heparin could be neutralized by protamine sulfate. From these observations, it was concluded that liposome-encapsulation of heparin results in the prolonged anticoagulant effect in vivo and lipo-heparin may be applicable for clinical use, after further studies on side effects of liposomes are completed.
D000818:Animals; D001777:Blood Coagulation / Q000187:drug effects; D001780:Blood Coagulation Tests; D006493:Heparin / Q000378:metabolism / Q000627:therapeutic use*; D007275:Injections, Intravenous; D008081:Liposomes / Q000008:administration & dosage*; D009500:Neutralization Tests; D011479:Protamines / Q000008:administration & dosage / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D008081:Liposomes; D011479:Protamines; D006493:Heparin