[Synergetic taste masking of lipid coating and beta-cyclodextrin inclusion]

Paracetamol was used as a model drug in this study to investigate the synergetic effects of lipid coating and beta-cyclodextrin (beta-CD) inclusion for masking the bitter taste of poorly soluble drugs. To control the concentration as low as possible of the free drug which produced a bitter taste, a kinetic model was established to calculate the drug distribution theoretically among the free drug in medium, lipid coated particles and molecular inclusion on the basis of the preparation and characterization of the lipid microspheres, so as to select the proper amount of beta-CD. Finally, the synergetic drug delivery systems were prepared and characterized by 1H nuclear magnetic resonance (1H NMR), molecular simulation and the electronic tongue. As a result, the drug release rate constant (k) of the lipid microspheres coated with octadecanol was determined as 0.001 270 s(-1). Then, the synergetic drug delivery systems were prepared with the ratio of 6.74 : 1 (w/w) for beta-CD and paracetamol. The chemical shift values for the fingerprint peaks of paracetamol all increased and hydrogen bonds were formed between the oxygen on the phenolic hydroxyl group, the nitrogen on the imino in paracetamol and the hydrogens on the hydroxyl groups in beta-CD. The results tested by the electronic tongue indicated that the paracetamol, lipid microspheres, beta-CD inclusion and their mixture showed different taste characteristics, with the bitterness order of the synergetic drug delivery systems approximately lipid microspheres < beta-CD inclusion < paracetamol, which confirmed the synergetic taste masking effects of lipid coating and beta-CD molecular inclusion. In summary, the synergetic taste masking was jointly achieved through the retard of the drug release by the lipid coating and the inclusion of the free paracetamol by beta-CD through hydrogen bonds.