Formation of inclusion-complexes between cyclodextrins, as mobile-phase additives in RPTLC, and fluoxetine, norfluoxetine, and promethazine

Inclusion complex formation and the potential separation of racemates of fluoxetine (FL) and norfluoxetine (NR), and of promethazine (PR) and its structural isomer isopromethazine (i-PR), have been investigated by reversed-phase thin-layer chromatography with hydroxypropyl-beta-cyclodextrin (HP-beta-CD) and beta-cyclodextrin (beta-CD) as mobile-phase additives, The results were compared with those from analogous studies in HPLC and capillary electrophoresis, Although the high affinity of the drugs for the stationary phase limited the selection of suitable chromatographic conditions, complex formation was evident with both types of cyclodextrin for all three drugs. Use of HP-beta-CD enables the successful separation of the enantiomers of FL and NL and the positional isomers of promethazine.