School of Pharmacy, University of Otago, PO Box 56, Dunedin 9054, New Zealand.
Int J Pharm. 2013 Nov 18;456(2):560-8. doi: 10.1016/j.ijpharm.2013.08.009. Epub 2013 Aug 18.
The purpose of the present study was to investigate lecithin-rice bran oil rheological properties with the view to consider these as potential saliva substitutes in patients with severe xerostomia and salivary hypofunction. Pseudo-ternary phase diagrams of rice bran oil, lecithin and water mixtures were constructed and characterised using polarising light microscopy. Viscoelastic properties, which we hypothesise are important determinants in product performance, were analysed using both flow and oscillatory rheology. Rheological properties were influenced by composition, frequency and shear stress. Frequency-dependent viscoelasticity was observed in some formulations where viscosity dominated (tanδ>1) at frequencies under 5 Hz and elasticity dominated (tanδ<1) at higher frequencies. Threshold frequencies were determined for each formulation, where a peak in loss tangent was observed, coinciding with a reduction in the storage modulus and increase in loss modulus. The frequency-dependent behaviour of emulsions are of interest because these combinations exhibit viscous behaviour at low frequencies, which may improve lubrication of the oral cavity at rest, whereas increased elasticity at higher frequencies may improve retention during higher-shear tasks such as swallowing and speaking.
本研究旨在探讨卵磷脂-米糠油的流变性能，以期将其作为严重口干和唾液分泌功能低下患者的潜在唾液替代品。采用偏光显微镜构建并表征了米糠油、卵磷脂和水混合物的拟三元相图。使用流变仪分别对流动和振荡流变学进行了分析，以研究我们假设的对产品性能有重要影响的粘弹性特性。流变性能受组成、频率和剪切应力的影响。在某些配方中观察到频率依赖性粘弹性，其中在低于 5 Hz 的频率下，粘度占主导地位（tanδ>1），而在较高频率下，弹性占主导地位（tanδ<1）。确定了每个配方的阈值频率，在该频率下，损耗角正切出现峰值，同时储能模量降低，损耗模量增加。乳液的频率依赖性行为很有趣，因为这些组合在低频下表现出粘性行为，这可能改善口腔在休息时的润滑，而在较高频率下弹性增加可能在吞咽和说话等较高剪切力任务中提高保留率。
