Host-guest kinetic interactions between HP-β-cyclodextrin and drugs for prediction of bitter taste masking

Cyclodextrins (CD) are widely used bitter taste masking agents, for which the binding equilibrium constant (K) for the drug-CD complex is a conventional parameter for quantitating the taste masking effects. However, some exceptions have been reported to the expected relationship between K and bitterness reduction and the relationship between kinetic parameters of a drug-CD interaction, including association rate constant (K_a) and disassociation rate constant (K_d), and taste masking remains unexplored. In this study, based upon a database of kinetic parameters of drugs-HP-β-CD generated by Surface Plasmon Resonance Imaging for 485 drugs, the host-guest kinetic interactions between drugs and HP-β-CD for prediction of taste masking effects have been investigated. The taste masking effects of HP-β-CD for 13 bitter drugs were quantitatively determined using an electronic gustatory system (α-Astree e-Tongue). Statistical software was used to establish a model based on Euclidean distance measurements, K_a and K_d of the bitter drugs/HP-β-CD-complexes (R²=0.96 and P<0.05). Optimized parameters, K_a³, K_d, K_aK_d, K_d³, K_a² and K_a/K_d with notable influence, were obtained by stepwise regression from 12 parameters derived from K_a, K_d and K (K_a/K_d). 10-fold cross-validation was used to verify the reliability of the model (correlation coefficient of 0.84, P<0.05). The established model indicated a relationship between K_a, K_d, K and taste masking by HP-β-CD and was successful in predicting the extent of taste masking by HP-β-CD of 44 bitter drugs, which was in accordance with the literature reported. In conclusion, the relationship between kinetics of drug-CD interactions and taste masking was established and providing a new strategy for predicting the cyclodextrin mediated bitter taste masking.