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Comparative Pharmacokinetics of Free Muramyl Tripeptide Phosphatidyl Ethanolamine (MTP-PE) and Liposomal MTP-PE

1993; Elsevier BV; Volume: 82; Issue: 10 Linguagem: Inglês

10.1002/jps.2600821005

1520-6017

Brigitte Gay, Jean-Michel A. Cardot, Christian Schnell, Peter van Hoogevest, Daniel Gygax,

Advanced biosensing and bioanalysis techniques

□ The comparative pharmacokinetics of free MTP-PE (muramyl tripeptide phosphatidyl ethanolamine) and MTP-PE entrapped in negatively charged multilamellar liposomes (liposomal MTP-PE) was evaluated in rats at a bolus intravenous (iv) dose of 0.2 mg/kg and in dogs at a bolus iv dose of 0.1 mg/kg. Additional studies were performed with the free form in rats (1.4 mg/kg, bolus iv) and dogs (1 mg/kg, bolus iv) and with the liposomal form in dogs (0.5 mg/kg, bolus iv). Plasma samples were obtained at various times up to 48 h postinjection and assayed for the drug by a chemiluminescence immunoassay. The pharmacokinetic data regarding liposomal MTP-PE describe the distribution of free drug released from liposomes and total drug concentrations. The present studies demonstrate that the distribution characteristics of MTP-PE changed dramatically depending on the dosage form. The elimination kinetics of free MTP-PE from blood is substantially slower than that of the liposomal drug. For liposomal MTP-PE, free drug levels in plasma are very low compared with free MTP-PE. In rats at a dose of 0.2 mg/kg, 96% of MTP-PE contained in liposomes is removed from the plasma compartment 10 min after injection, and in dogs at a dose of 0.1 mg/kg, 100% of MTP-PE contained in liposomes is removed in the same time period. This rapid phase of liposome clearance is followed by a slower rate of clearance for the remainder of the liposomes in rats at a dose of 0.2 mg/kg and in dogs at a dose of 0.5 mg/kg.