Swaminathan Vidya, Cobb Jaclyn, Saracovan Ilie
Pfizer Global R&D, Groton Laboratories, Groton, CT 06340, USA.
Int J Pharm. 2006 Apr 7;312(1-2):158-65. doi: 10.1016/j.ijpharm.2006.01.014. Epub 2006 Feb 15.
The objective of the study was to determine whether lubrication of pharmaceutical powders with magnesium stearate (MgSt) results in a change in the surface energy of the powder, and to assess whether surface energy changes, if any, are correlated to lubricant concentration and blend time. The surface energies of microcrystalline cellulose (MCC), lactose, and blends of each material with MgSt, prepared at a range of concentrations and blending times were measured using inverse gas chromatography. The physical distribution of MgSt in the blend was mapped by energy dispersive spectrometry. Overall, there was a reduction in the dispersive surface energy of MCC-MgSt blends with increase in MgSt concentration, that was attributed to increasing coverage of the high-energy sites on microcrystalline cellulose by magnesium stearate. MgSt concentration had a larger effect on dispersive energy than the blending time of the powder with lubricant. X-ray maps of blend samples indicated a heterogeneous distribution of the lubricant in the blend and on the excipient particles. Measurement of the specific component of surface energy indicated that MgSt interacts with excipient powders through non-specific forces rather than acid-base interactions. No distinction among lactose-MgSt blends could be made on the basis of dispersive energy because of similar surface energies of the native materials.
该研究的目的是确定用硬脂酸镁（MgSt）对药用粉末进行润滑是否会导致粉末表面能发生变化，并评估表面能的变化（如果有的话）是否与润滑剂浓度和混合时间相关。使用反相气相色谱法测量了微晶纤维素（MCC）、乳糖以及每种材料与MgSt在一系列浓度和混合时间下制备的混合物的表面能。通过能量色散光谱法绘制了MgSt在混合物中的物理分布。总体而言，随着MgSt浓度的增加，MCC-MgSt混合物的分散表面能降低，这归因于硬脂酸镁对微晶纤维素上高能位点的覆盖增加。MgSt浓度对分散能的影响比粉末与润滑剂的混合时间更大。混合物样品的X射线图表明润滑剂在混合物和辅料颗粒中的分布不均匀。表面能特定成分的测量表明，MgSt通过非特异性力而非酸碱相互作用与辅料粉末相互作用。由于天然材料的表面能相似，因此无法根据分散能对乳糖-MgSt混合物进行区分。
