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Rheology of Cellulose Ether Excipients Designed for Hot Melt Extrusion
Biomacromolecules ( IF 5.5 ) Pub Date : 2018-10-15 00:00:00 , DOI: 10.1021/acs.biomac.8b01306
Tirtha Chatterjee 1 , Kevin P. O’Donnell 2 , Mark A. Rickard 3 , Brian Nickless 4 , Yongfu Li 3 , Valeriy V. Ginzburg 4 , Robert L. Sammler 4
Affiliation  

A new family of cellulosic ether polymeric excipients has been recently engineered for fabrication of amorphous solid dispersions of active pharmaceutical ingredients via hot-melt extrusion (HME). These hydroxypropyl methyl cellulose excipients enable plasticizer-free melt processing at much lower temperatures (135–160 °C) due to their substantially reduced glass transition temperatures (Tg = 98–110 °C). The novel amorphous cellulose ethers were found to be rheologically solidlike well above their glass transition (Tg + 70 °C). We demonstrate that in the pharmaceutically relevant HME processing temperature range these polymers behave similarly to yield-stress fluids and flow only when the applied stress exceeds a critical stress value. This critical stress value (0.50 ± 0.05 MPa, 150 °C) is surprisingly high but is easily achieved under typical HME conditions. The origin of their yield-stress fluidlike behavior is hypothesized to arise from hydrogen bonds of the HPMC materials that act as physical cross-links and do not relax within the measured temperature and time window unless the applied stress exceeds the critical stress value. Support for this hypothesis arises from infrared spectroscopic estimates of the free and bound hydrogen bond levels at end-use temperatures.

中文翻译:

用于热熔挤出的纤维素醚辅料的流变学

最近,人们设计了一个新的纤维素醚聚合物赋形剂家族,用于通过热熔挤出(HME)制造活性药物成分的无定形固体分散体。这些羟丙基甲基纤维素赋形剂由于大大降低了玻璃化转变温度(T g = 98-110°C),因此可以在更低的温度(135–160°C)下进行无增塑剂的熔融加工。发现新型无定形纤维素醚在其玻璃化转变温度(T g+ 70°C)。我们证明,在药学上相关的HME加工温度范围内,这些聚合物的行为类似于屈服应力流体,仅当施加的应力超过临界应力值时才流动。该临界应力值(0.50±0.05 MPa,150°C)令人惊讶地很高,但在典型的HME条件下很容易达到。据推测,它们的屈服应力类似流体的行为的起因是由HPMC材料的氢键引起的,该氢键充当物理交联,并且在所测温度和时间窗口内不会松弛,除非所施加的应力超过临界应力值。对这一假设的支持来自于最终使用温度下游离和结合的氢键水平的红外光谱估计。
更新日期:2018-10-15
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