Chiral liquid membrane containing a dipentyl-b-cyclodextrin : enantioselective partition of racemic pseudoephedrine

Teerapol Srichana, D. of Pharmaceutical Tech., F. of Pharmaceutical Sci., PSU.
Roongnapa Suedee, Asst. Prof., D. of Pharmaceutical Chemistry, F. of Pharmaceutical Sci., PSU. Corresponding e-mail : srteerap@ratree.psu.ac.th

Published : Thai J Pharm Sci 1999, 23, 187-196.
Key words : chiral liquid membrane, cyclodextrin derivative, pseudoephedrine, enantioselective partition

This study was designed to examine enantioselective transport of pseudoephedrine through a two phase and chiral liquid membrane containing heptakis (di-O-pentyl)-b-cyclodextrin (dipentyl-b-CD). The molar ratio of dipentyl-b-CD to pseudoephedrine and pH of aqueous phase significantly affected the partition of pseudoephedrine enantiomers from aqueous to dipentyl-b-CD phase (P<0.05). A 2.5 molar ratio of dipentyl-b-CD gave the best enantioselective partition of pseudoephedrine. The chiral liquid membrane transport of racemic pseudoephedrine was examined using a U-tube composed of aqueous donor phase (pH 6.5) containing pseudoephedrine, bulk liquid membrane containing dipentyl-b-CD in dichloromethane and aqueous receiving phase (pH 3.0). It was found that the transport of (+)-pseudoephedrine from donor phase to organic phase was superior to that of (-)-isomer. While the partition of (-)-pseudoephedrine from liquid membrane phase into a receiving phase was greater than that of (+)-isomer with approximate ratio (-)/(+) of 3.5. It can be concluded that different isomers of pseudoephedrine interacted with chiral liquid membrane in different degrees; therefore the liquid membrane is able to resolve the enantiomers of pseudoephedrine.

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