INTERACTION OF LOCAL-ANESTHETICS WITH AN ANIONIC RECEPTOR-SITE - AN AB-INITIO SCF STUDY ON PROCAINE, LIDOCAINE, TOCAINIDE AND MEXILETINE AND THEIR HCO2- COMPLEXES

The ab initio SCF method was used to study the interaction of the loca l anaesthetics (LAs) procaine, lidocaine, tocainide and mexiletine wit h anionic receptor binding sites (Asp(-), Glu(-)) represented by forma te. In the case of procaine a two-centre binding site model for the bi nding of LAs was constructed. This model allows optimum interactions w ith the cationic amine part and the polar oxygen regions of procaine. The binding of procaine base was also investigated proving that this i nteraction is much weaker than the interaction of charged LA with its receptor binding sites. Finally, the effect of medium was studied (emp loying direct reaction field theory). The solvent changes the equilibr ium geometry and decreases the energy of the complexes.