Analiza kiralnih lijekova kapilarnom elektroforezom

Abstract

The importance of enantiomer purity control was perceived in 1960s after the Thalidomide disaster. Enantiomers can show different pharmacological efficiency, bioavailability and therapeutic indications. Very often only one enantiomer is active, while the other can have no activity whatsoever, or can even be toxic. Therefore, methods that enable separation and purity evaluation of enantiomers are very important. Most often used techniques are polarimetry, circular dichroism, roentgen diffraction and chiral chromatography. Separation techniques frequently used are high performance liquid chromatography, gas chromatography and capillary electrophoresis. Capillary electrophoresis is a very fast and cheap technique. The most often used chiral separators in capillary electrophoresis are ciclodextrins. They are cyclic oligosaharyds, composed of a-D-glucopyranoside units bound together in a ring. Topologically cyclodextrins are represented as toroids with the larger and the smaller openings of the toroid exposing to the solvent secondary and primary hydroxyl groups respectively. The exterior of the toroid is hydrophilic making it water soluble, while the interior is relatively hydrophobic. This enables the cyclodextrin to form inclusion complexes with drug molecules. One of the enantiomers forms stronger interactions with cyclodextrin then the other cyclodextrin, which ensures enantiomer separation. Enantioselective capillary electrophoretic method using cyclodextrins are used in pharmaceutical analysis, cosmetic and food industry, in forensic science and in environmental protection. In pharmaceutical analysis they are used for determination of stereochemical purity, especially when it is necessary to quantify one of the enanitomers in the presence of large quantity of other stereoisomers