Needham David
Department of Mechanical Engineering and Material Science, Duke University, Durham, NC 27708 USA.
School of Pharmacy, University of Nottingham, Nottingham, NG7 2RD UK.
AAPS Open. 2023;9(1):9. doi: 10.1186/s41120-023-00072-x. Epub 2023 Apr 14.
The low solubility, weak acid drug, niclosamide is a host cell modulator with broad-spectrum anti-viral cell-activity against many viruses, including stopping the SARS-CoV-2 virus from infecting cells in cell culture. As a result, a simple universal nasal spray preventative was proposed and investigated in earlier work regarding the dissolution of niclosamide into simple buffers. However, starting with pharmaceutical grade, niclosamide represents a new 505(b)(2) application. The motivation for this second paper in the series was therefore to explore if and to what extent niclosamide could be extracted from commercially available and regulatory-approved niclosamide oral tablets that could serve as a preventative nasal spray and an early treatment oral/throat spray, with possibly more expeditious testing and regulatory approval.
Measurements of supernatant niclosamide concentrations were made by calibrated UV-Vis for the dissolution of niclosamide from commercially available Yomesan crushed into a powder for dissolution into Tris Buffer (TB) solutions. Parameters tested were as follows: time (0-2 days), concentration (300 µM to -1 mM), pH (7.41 to 9.35), and anhydrous/hydrated state. Optical microscopy was used to view the morphologies of the initial crushed powder, and the dissolving and equilibrating undissolved excess particles to detect morphologic changes that might occur.
: Niclosamide was readily extracted from powdered Yomesan at pH 9.34 TB at starting Yomesan niclosamide equivalents concentrations of 300 µM, 600 µM, and 1 mM. Peak dissolved niclosamide supernatant concentrations of 264 µM, 216 µM, and 172 µM were achieved in 1 h, 1 h, and 3 h respectively. These peaks though were followed by a reduction in supernatant concentration to an average of 112.3 µM ± 28.4 µM after overnight stir on day 2. : For nominal pHs of 7.41, 8.35, 8.85, and 9.35, peak niclosamide concentrations were 4 µM, 22.4 µM, 96.2 µM, and 215.8 µM, respectively. Similarly, the day 2 values all reduced to 3 µM, 12.9 µM, 35.1 µM, and 112.3 µM. A heat-treatment to 200 °C dehydrated the niclosamide and showed a high 3 h concentration (262 µM) and the least day-2 reduction (to 229 µM). This indicated that the presence, or formation during exposure to buffer, of lower solubility polymorphs was responsible for the reductions in total solubilities. These morphologic changes were confirmed by optical microscopy that showed initially featureless particulate-aggregates of niclosamide could grow multiple needle-shaped crystals and form needle masses, especially in the presence of Tris-buffered sodium chloride, where new red needles were rapidly made. : A scaled-up 1 L solution of niclosamide was made achieving 165 µM supernatant niclosamide in 3 h by dissolution of just one fifth (100 mg niclosamide) of a Yomesan tablet.
These comprehensive results provide a guide as to how to utilize commercially available and approved tablets of niclosamide to generate aqueous niclosamide solutions from a simple dissolution protocol. As shown here, just one 4-tablet pack of Yomesan could readily make 165 L of a 20 µM niclosamide solution giving 16,500 10 mL bottles. One million bottles, from just 60 packs of Yomesan, would provide 100 million single spray doses for distribution to mitigate a host of respiratory infections as a universal preventative-nasal and early treatment oral/throat sprays throughout the world.
pH dependence of niclosamide extraction from crushed Yomesan tablet material into Tris buffer (yellow-green in vial) and Tris-buffered saline solution (orange-red in vial). Initial anhydrous dissolution concentration is reduced by overnight stirring to likely monohydrate niclosamide; and is even lower if in TBSS forming new niclosamide sodium needle crystals grown from the original particles.
The online version contains supplementary material available at 10.1186/s41120-023-00072-x.
低溶解度的弱酸药物氯硝柳胺是一种宿主细胞调节剂，对多种病毒具有广谱抗病毒细胞活性，包括在细胞培养中阻止严重急性呼吸综合征冠状病毒2（SARS-CoV-2）病毒感染细胞。因此，在早期关于氯硝柳胺溶解于简单缓冲液的研究中，提出并研究了一种简单的通用鼻喷雾剂预防方法。然而，从药用级开始，氯硝柳胺代表了一种新的505(b)(2)申请。因此，本系列第二篇论文的目的是探讨氯硝柳胺能否以及在多大程度上可以从市售且经监管批准的氯硝柳胺口服片剂中提取出来，这些片剂可作为预防性鼻喷雾剂和早期治疗用口腔/咽喉喷雾剂，可能会加快测试和监管批准的进程。
通过校准的紫外可见光谱法测量上清液中氯硝柳胺的浓度，以研究市售的灭绦灵（Yomesan）碾碎成粉末后在三羟甲基氨基甲烷缓冲液（TB）溶液中的溶解情况。测试的参数如下：时间（0 - 2天）、浓度（300 μM至1 mM）、pH值（7.41至9.35）以及无水/水合状态。使用光学显微镜观察初始碾碎粉末的形态，以及溶解和平衡过程中未溶解的过量颗粒，以检测可能发生的形态变化。
在起始灭绦灵氯硝柳胺当量浓度为300 μM、600 μM和1 mM的情况下，在pH 9.34的TB中，氯硝柳胺很容易从碾碎的灭绦灵中提取出来。在1小时、1小时和3小时时，溶解的氯硝柳胺上清液峰值浓度分别达到264 μM、216 μM和172 μM。然而，在第2天过夜搅拌后，这些峰值之后上清液浓度降低至平均112.3 μM ± 28.4 μM。对于名义pH值为7.41、8.35、8.85和9.35的情况，氯硝柳胺的峰值浓度分别为4 μM、22.4 μM、96.2 μM和215.8 μM。同样，第2天的值均降至3 μM、12.9 μM、35.1 μM和112.3 μM。对氯硝柳胺进行200°C的热处理使其脱水，结果显示3小时时浓度较高（262 μM），第2天的降低幅度最小（降至229 μM）。这表明较低溶解度的多晶型物的存在或在暴露于缓冲液过程中的形成是总溶解度降低的原因。这些形态变化通过光学显微镜得到证实，显微镜显示最初无特征的氯硝柳胺颗粒聚集体可以生长出多个针状晶体并形成针状聚集体，特别是在含有三羟甲基氨基甲烷缓冲氯化钠的情况下，会迅速形成新的红色针状晶体。通过溶解仅五分之一（100 mg氯硝柳胺）的一片灭绦灵片剂，在3小时内制备了1 L放大规模的氯硝柳胺溶液，上清液中氯硝柳胺浓度达到165 μM。
这些综合结果为如何利用市售且经批准的氯硝柳胺片剂通过简单的溶解方案制备氯硝柳胺水溶液提供了指导。如此处所示，仅一包4片装的灭绦灵就可以轻松制备165 L 20 μM的氯硝柳胺溶液，可装16,500个10 mL的瓶子。仅60包灭绦灵就能生产100万个瓶子，可提供1亿次单次喷雾剂量，作为全球通用的预防性鼻喷雾剂和早期治疗用口腔/咽喉喷雾剂，用于减轻一系列呼吸道感染。
碾碎的灭绦灵片剂材料中氯硝柳胺提取到三羟甲基氨基甲烷缓冲液（小瓶中为黄绿色）和三羟甲基氨基甲烷缓冲盐水溶液（小瓶中为橙红色）的pH依赖性。初始无水溶解浓度通过过夜搅拌降低，可能形成一水合氯硝柳胺；如果在三羟甲基氨基甲烷缓冲盐溶液中，由于从原始颗粒生长出新的氯硝柳胺钠针状晶体，浓度会更低。
在线版本包含可在10.1186/s41120 - 023 - 00072 - x获取的补充材料。
