Optical isomer separation of potential analgesic drug candidates by using capillary electrophoresis

Using cyclodextrin capillary zone electrophoresis (CD-CZE), baseline separa tion of synthetic potential analgesic drug diastereoisomer candidates 6,11- dimethyl-1,2,3,4,5, 6-hexahydro-3-[(2'-methoxycarbonyl-2'-phenylcyclopropyl )methyl]-2,6-methano-3-benzazocin-8-ol (MPCB) and 6,11-dimethyl-1,2,3,4,5,6 -hexahydro-3-{[2'-methoxycarbonyl-2'(4-chlorophenyl)cyclopropyl]methyl}-2,6 -methano-3-benzazocin-8-ol (CCB) was achieved. Among the cyclodextrins test ed (hydroxypropyl-, carboxy-methyl- and sulfobutyl-beta-cyclodextrin (HP-be ta-CD, CM-beta-CD and SBE-beta-CD)) SBE-beta-CD was found to be the most ef fective complexing agent, allowing good optical isomer separation. Resoluti on was also influenced by the CD concentration, pH of the buffet and presen ce of organic modifier in the background electrolyte. The optimum experimen tal conditions for the separation of studied analgesic drugs were found usi ng 25 mM berate buffer at pH 9 containing 40 mu of SBE-beta-CD and 20% v/v of methanol. Using the above-mentioned background electrolyte, it was also possible to separate, in the same run, the enantiomers of normetazocine (NM Z) as well as the optical isomers of (+/-)-cis-2-chloromethyl-1-phenyl cycl opropancarboxylic acid methyl ester (PCE) or (+/-)-cis-2-chloromethyl-1-(4- chlorophenyl)cyclopropancarboxylic acid methyl ester (CPCE) reagents used i n the synthesis of the studied analgesic drugs).