Is there any method to release or extract the drug molecules from beta-cyclodextrin inclusion complex? I want to release a drug from the complex, can I degrade or dissolve the cyclodextrin part?
Hello Souptik Bhattacharya
In which organic solvent your compound is soluble in? I would suggest to use a mixture of solvent for example (e.g. water/organic solvent) where the percentage of water would be very small. In that manner, your hosted compound would have more affinity with the organic solvent (in solution) than with the inner part of your cyclodextrin and you could potentially extract your drug in this manner. The organic the solvent that you will use needs to be miscible with water.
Best regards,
Marie B.
Hi Souptik,
1:1 EtOH-water mixtures usually destroy the complexes. Additionally, the CDs are more soluble in that solution, too. For UV analysis this is ideal (of course both the calibration curve and blank should be recorded also in this ~ 50 v/v% EtOH).
If you also want to isolate the drug molecule, the process is more complex. In the case of salts the pH modification of the solution can allow extraction (DCM, CHCl3, or toluene). Usually, the ionizable molecules have pH deőpendent affinities to CDs. Of course, the neutral molecules can be extracted without pH manipulation. Addition of inorganic salts (e.g. NaCl) can also increase the extraction efficacy. Toluene can have also results in the precipitation of the CD/toluene complex which is useful.
The 1:1 EtOH-water can also be used in this case but you may encounter the problem of emulsion. Not only because the 50% EtOH can dissolve the poorly miscible organic solvent but the CDs can cause a similar effect.
In a beneficial case, you can apply the ligand exchange method: add a better host, and if the competitor is less soluble than the problem is reduced to separate two compounds. E.g. the toluene forms very insoluble complex with a- and bCD, and a-naphtol with gCD. In this case, extraction can also a useful method.
But: please remember that usually the mass ratio of the guest is low, and generally the CD is in excess. To shift the equilibrium to the favorite direction you need to use (molar) excess from the competitor. Additionally, the exchange of the host (or in general, the complex formation) is not a minute reaction.
Good luck,
Laszlo
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