Requirements for Designing a Freeze Casting Process for Drugs – Rheological Properties of Suspensions

Abstract

Freeze casting is a useful molding technique for the production of porous, fast dissolving tablets of foods and pharmaceuticals. In order to optimize the freeze casting process, the slurries, and also the characteristics of the freeze‐casted products, multifunctional additives are usually employed. For further applications of these procedures in industrial processes, the suspension characteristics should be known. This case study focuses on the rheological properties of paracetamol suspensions. The effects of modified starch as an additive, the solid loadings, and the temperature on the flow behavior and viscosities of the suspensions were investigated. It was found that most suspensions are thixotropic systems. The viscosity of the suspensions is highly sensitive with respect to the studied factors, such as shear rate, shearing time, temperature, solid loading, and additive content. Optimized conditions were found and are recommended for industrial use.

Freeze casting – A review of processing, microstructure and properties via the open data repository, FreezeCasting.net

“…Concurrent investigations of freeze-cast materials for other ceramic-based applications, including filtration membranes [6][7][8] and fuel cell electrodes [9][10][11][12][13][14][15][16], began to reveal the true versatility of the technique. Freeze-casting of metals [17], pharmaceuticals [18][19][20][21][22][23][24], and foodstuffs [25] was demonstrated within the same decade. From the early 2000's to 2017, the number and diversity of potential applications for these materials grew considerably; applications investigated include substrates for supercapacitors [26][27][28][29][30][31][32], photocatalysis [33][34][35][36][37][38][39][40][41][42][43], liquid chromatography [44], sensors (e.g.…”

New Aspects in the Formulation of Drugs Based on Three Case Studies

“…However, they tend to agglomeration, which often occurs during the usage as well as during the manufacturing process [9]. To solve this issue, a porous tablet tailored by the freeze casting process represents a new approach [9,10,11,12,13,14].…”

“…Silica sol (Bindzil) was found to be a very effective binder; however, it also slowed down the release of drugs, because of its strong binding function [19]. In other case studies [12,13,14], modified starch as additive was successfully used. Its content was found to be the main factor in control of the release rate in paracetamol freeze casted tablets.…”

External Field Assisted Freeze Casting

“…Freeze casting is a relatively simple alternative that overcomes many of these limitations for fabricating porous anisotropic ceramics [28][29][30], polymers [31,32], metals [33,34] or composites [35,36], often exhibiting high compressive properties [37]. This method has potential applications in cryobiology [38], remediation of contaminated media [39,40], chemical analyses [41], liquid chromatography [42], energy storage [43,44], photocatalysis [45,46], sensors [47,48], pharmaceuticals [49] and the food industry [50,51]. In this review, we highlight important aspects of external field assisted freeze casting, focusing on the theory and experimental results.…”