Chiral drug separation principles

A commercial CE system and a micropacked capillary was used to separate N—, O—, and S-containing heterocyclic compounds. Migration time reproducibility, linearity, and detector response was found to be comparable to HPLC. A study of the heterocyclic compound s elution order followed that predicted by the octanol-water partition coefficients (354). While chiral CEC provides improved resolution and higher efficiencies, additional work is needed since chiral CEC capillaries are not available commercially. The separation principles and chiral recognition mechanism for the separation of enantiomers have been reviewed (355). Furthermore, a comprehensive collection of drug applications and other compounds of interest has been reported (356). Direct enantiomeric separations by CEC were studied using a capillary packed with alpha-1-acid glycoprotein chiral stationary phase (357). Chiral resolution was achieved for enantiomers of benzoin, hexobarbital, pentobarbital, fosfamide, disopyramide, methoprolol, oxprenolol, and propanolol. The effects of pH, electrolyte concentration, and con-... 

Membrane bioreactors have been reported for the production of diltiazem chiral intermediate with a multiphase/extractive enzyme membrane reactor [15, 16]. The reaction was carried out in a two-separate phase reactor. Here, the membrane had the double role of confining the enzyme and keeping the two phases in contact while maintaining them in two different compartments. This is the case of the multiphase/ extractive membrane reactor developed on a productive scale for the production of a chiral intermediate of diltiazem ((2R,3S)-methylmethoxyphenylglycidate), a drug used in the treatment of hypertension and angina [15]. The principle is illustrated in... 

Solvent Extraction Principles. Forensic Sciences Drug Screening in Sport Systematic Drug Identification. Gas Chromatography Mass Spectrometry Chiral Separations. Immunoassays, Techniques Enzyme Immunoassays Luminescence Immunoassays. Liquid Chromatography Column Technology. Pharmaceutical Analysis Sample Preparation. 

About 40% of the drugs contain at least one chiral center. Isomers have very close chemical structures however, in many cases they exhibit different biological effects, bind to proteins, or are metabolized differently. Thus, chiral separation is very important. The principles of this technique in CE depend on the addition to the buffer an additive compound with a special cavity such as cyclo-dextrins, heparin, or certain antibiotics, which... 

In CE, the same principle described above is used. Here too, the technique depends on the use of chiral additives which have differing eiflinities for the isomers and hence are usually termed enantioselective additives. In CE the enantioselective additives are not stationary but are moved past the detector by the EOF, or a combination of EOF and electrophoretic mobility. In this sense chiral separations can be regarded as a specialized form of MECC. This has found particular application in the ph irmaceutical industry where an assessment of the optical purity of drugs can be of importance. 

Moreover, MEEKC has been shown to be a highly apphcable system for the analysis of complex mixtures such as mirlticomponent formirlations, related substances of active principles and excipients in birlk drugs, chiral analysis, natural products, and bioanalytical separations. 

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