ABSTRACT
There has not been an ideal reproducible small-animal model of chronic hyperendotoxemia to date. Our drug delivery system (DDS) is a new technology that can deliver a drug conveniently to a target organ at an optional rate. 2-Hydroxyethyl methacrylate (HEMA) was used as a carrier of lipopolysaccharide (LPS), and diethylene glycol and polyethylene glycol dimethacrylates (2G, 4G, 9G) were used as cross-linking agents. A mixed solution of HEMA and di(poly)ethylene glycol dimethacrylate was charged into a glass tube with or without LPS and polymerized by ultraviolet irradiation. This polymer was cut into DDS tablets of the same size with or without LPS. A mixture with HEMA:4G = 1:3 was the most suitable composition to release a constant concentration of LPS. We also developed a novel rat model of chronic hyperendotoxemia. Four DDS tablets, each containing 15 mg LPS, were implanted into the abdominal cavity of rats in the LPS group. The control group was implanted with four DDS tablets without LPS. Plasma levels of LPS in the study group were maintained at more than 2,000 pg/ml for 72 h after implantation. Weight gain was lower and body temperature was higher in the LPS group than in the control group. Plasma levels of inter leukin (IL)-6 in the LPS group were higher than in the control group only during the initial 12 h after implantation of DDS tablets. The white blood cell count at 24 h and platelet counts at 24, 48, and 72 h in the LPS group were lower than those in the control group. These results indicate that chronic hyperendotoxemia was maintained for 72 h by continuous release of LPS from the DDS. Moreover, the intensity of endotoxemia could be varied by varying the number of DDS tablets. It is concluded that our new rat model using LPS-DDS will be applicable and useful as a model of chronic hyperendotoxemia.
Subject(s)
Drug Delivery Systems/methods , Endotoxemia/metabolism , Escherichia coli Infections/metabolism , Lipopolysaccharides/administration & dosage , Methacrylates/administration & dosage , Animals , Chronic Disease , Cross-Linking Reagents/administration & dosage , Cross-Linking Reagents/metabolism , Disease Models, Animal , Drug Carriers , Ethylene Glycols/administration & dosage , Ethylene Glycols/metabolism , Interleukin-6/blood , Lipopolysaccharides/metabolism , Male , Methacrylates/metabolism , Polyethylene Glycols/administration & dosage , Polyethylene Glycols/metabolism , Rats , Rats, WistarABSTRACT
Luteinizing hormone-releasing hormone (LH X RH) agonist can be administered daily to patients with prostatic cancer with resulting clinical efficacy. A sustained drug release formulation of an LH X RH agonist, (D-Leu6)-des Gly-NH2(10)-LH X RH ethylamide (leuprolide)-vinyl polymer composite, was prepared by means of radiation-induced polymerization under a supercooled state. The sustained release of leuprolide from subcutaneously implanted leuprolide-vinyl polymer composite (14 mm in diameter and 4 mm in thickness) was obtained over a period of several months in five patients with prostatic cancer. Serum testosterone levels began to decrease on the tenth day, fell below 1 ng/ml after three weeks of implantation, and thereafter remained at the castration level until removal of the polymer composite. Clinical improvement was associated with serum hormonal changes, and support this as a novel and superior method of administration of LH X RH agonist.
