PtRACETAM-INDUCED CHANGES TO MEMBRANE PHYSICAL PROPERTIES A COMBINED APPROACH BY 31P NUCLEAR MAGNETIC RESONANCE AND

Abstract-Piracetam, Nootropil@ (Z0x0-1-pyrrolidine acetamide), is a drug promoting erythrocyte deformabil- ity. To establish the mode of action of this compound, we have investigated its influence,on the organization of model phospb3lipid membranes. 31P NMR data show that the drug induces a structural modification in lipo- somes made cf phosphatidylcholine and phosphatidylethanolamine. Our conformational analysis results have allowed the interpretation of the effect of piracetam on these model membranes: the specific interaction between the drug molecules and the phosphate headgroups induces a new organization of the lipids favouring formation of mobile drug;-phospholipid complexes that exhibit an isotropic-type signal in the 3’P NMR spectra. Key words: piracetam; model membrane; 3’P NMR; conformational analysis; isotropic structure; physical properties In most cases, all drugs that act in the human body interact with certain metabolic pathways and are trans- formed into one or more metabolites. However, pirace- tam, which is very soluble in water and only poorly soluble in organic media, is neither ionized nor bound by proteins. It is not metabolized; no metabolite of any sort has been evidenced (even when starting from radioactive carbon) in the excretory products (urine, faeces), the blood, the liver, or the brain [l]. In addition, piracetam improves red blood cell deformability