Cyclo dextrins cyclodextrin inclusion complexes

Only the hydrophobic and steric terms were involved in these equations. There are a few differences between these equations and the corresponding equations for cyclo-dextrin-substituted phenol systems. However, it is not necessarily required that the mechanism for complexation between cyclodextrin and phenyl acetates be the same as that for cyclodextrin-phenol systems. The kinetically determined Kj values are concerned only with productive forms of inclusion complexes. The productive forms may be similar in structure to the tetrahedral intermediates of the reactions. To attain such geometry, the penetration of substituents of phenyl acetates into the cyclodextrin cavity must be shallow, compared with the cases of the corresponding phenol systems, so that the hydrogen bonding between the substituents of phenyl acetates and the C-6 hydroxyl groups of cyclodextrin may be impossible. 

The plot of the reciprocal of k - kf against 1/[L] is linear, with a slope of 1 / [K(kc - kf)] and an intercept of 1 / (kc - kf). Figure 5.36 shows the stabilization of prostacyclin by the derivatives of P-cyclodextrin. However, not all inclusion complexes provide the stabilization of drugs. In many cases, drug degradation is enhanced via inclusion complex formation [e.g., prostaglandin E and E2/p-cyclo-dextrin (P-CD), aspirin/p-CD],... 

Simultaneously with the Harada s report on the first polyrotaxane, Wenz reported the preparation of polyrotaxanes from polyamines and a-cyclodex-trin in an aqueous solution [108]. a-Cyclodextrin forms inclusion complexes with poly(iminoundecamethylene) and poly(iminotrimethylene-iminode-camethylene) (Scheme 17). The rates of the inclusion of poly(iminounde-camethylene) by a-cyclodextrin are slow on the H NMR time scale in D20 at pH<6. The inclusion formation between poly(iminotrimethylene-imin-odecamethylene) and a-cyclo dextrin took 170 h to reach equilibrium. Wenz... 

IK Chun, DS Yun. Inclusion complexation of hydrocortisone butyrate with cyclo-dextrins and dimethyl- 3-cyclodextrin in aqueous solution and in solid state. Int J Pharm 96 91-103, 1993. 

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