ABSTRACT
The natural cyclodextrins are obtained from starch due to degradation by cycloglycosyl transferase amylase which is produced by the bacteria Bacillus macerans. Cyclodextrins with lipophilic inner cavities and hydrophilic outer surfaces are capable of interacting with a large variety of guest molecules to form non-covalent inclusion complexes. Cyclodextrins are classified according to their number of glucopyranose units. Osmotically controlled oral drug delivery systems are available to control the drug release based on the principle of osmosis. Solvent process requires an organic solvent mainly toluene, ethyl alcohol or acetone that acts as a complexing agent which extracts one type of cyclodextrin selectively and thus directs the enzyme reaction to produce particular type of cyclodextrin of interest. Inclusion complexes can be prepared by simply grinding the guest with cyclodextrin. In freeze-drying, physical mixture of guest and cyclodextrin is wetted with a small amount of buffer solution and is kneaded forming a homogeneous suspension which is then freeze-dried.
