DETERMINATION OF SALBUTAMOL ENANTIOMERS BY HIGH-PERFORMANCE CAPILLARYELECTROPHORESIS AND ITS APPLICATION TO DISSOLUTION ASSAYS

Capillary zone electrophoresis was successfully applied to the chiral separation of salbutamol after addition of a suitable cyclodextrin chi ral selector to the electrophoresis buffer. Parameters important in ac hieving enantiomeric separation are cyclodextrin type, mobile phase pH and applied field strength. In our study, salbutamol enantiomeric sep aration was obtained with the following conditions: heptakis (2,6-di-O -methyl)-beta-cyclodextrin in 40 mM Tris (pH 2.5) and at 15 kV, obtain ing a 3.09 resolution with migration times of 13.74 min for (R)-salbut amol and 13.98 min for (S)-salbutamol. Linearity, limit of quantitatio n, precision and accuracy were established using this method. The cali bration curve was linear in a range of 1-40 mu g ml(-1) of racemic sal butamol (0.5-20 mu g ml(-1) of each enantiomer). This method was appli ed to evaluate the enantioselective release of salbutamol and taking i nto account the hypothesis that one enantiomer of a chiral drug would be released faster than the other from a pharmaceutical dosage form co ntaining a racemic drug and a chiral excipient. For this purpose, matr ix tablets formed by chiral excipients such as hydroxypropylmethylcell ulose (HPMC) were considered. The release of the enantiomers of salbut amol from the formulations containing HPMC was found to be equivalent, with constant dissolution values (K) of 1.187 +/- 0.223% min(-n) for (R)-salbutamol and 1.076 +/- 0.268% min(-n) for (S) salbutamol. (C) 19 97 Elsevier Science B.V.