Molecular Dynamic Simulation of D-Mannitol Polymorphs in Solid State and in Solution Relating With Spontaneous Nucleation

A Critical Review on Engineering of d-Mannitol Crystals: Properties, Applications, and Polymorphic Control

d-mannitol is a common six-carbon sugar alcohol, which is widely used in food, chemical, pharmaceutical, and other industries. Polymorphism is defined as the ability of materials to crystallize into different crystal structures. It has been reported for a long time that d-mannitol has three polymorphs: β, δ, and α. These different polymorphs have unique physicochemical properties, thus affecting the industrial applications of d-mannitol. In this review, we firstly introduced the characteristics of different d-mannitol polymorphs, e.g., crystal structure, morphology, molecular conformational energy, stability, solubility and the analytical techniques of d-mannitol polymorphisms. Then, we described the different strategies for the preparation of d-mannitol crystals and focused on the polymorphic control of d-mannitol crystals in the products. Furthermore, the factors of the formation of different d-mannitol polymorphisms were summarized. Finally, the application of mannitol polymorphism was summarized. The purpose of this paper is to provide new ideas for a more personalized design of d-mannitol for various applications, especially as a pharmaceutical excipient. Meanwhile, the theoretical overview on polymorphic transformation of d-mannitol may shed some light on the crystal design study of other polycrystalline materials.

Selective Crystallization of d-Mannitol Polymorphs Using Surfactant Self-Assembly

Selective crystallization of polymorphs is highly sought after in industrial practice. Yet, state-of-the-art techniques either use laboriously engineered solid surfaces or strenuously prepared heteronucleants. We propose an approach where surfactants in solution self-assemble effortlessly into mesoscopic structures dictating the polymorphic outcome of the target solute. Sodium dodecyl sulfate (SDS) surfactant is used as a tailored additive to crystallize different polymorphic forms of a model active pharmaceutical ingredient, d-mannitol. Different mesoscopic phases of SDS template particular polymorphs: packed monolayers, micelles, and crystals favored the β, α, and δ forms of d-mannitol, respectively. A synergistic effect of topological templating and molecular interactions is proposed as the rationale behind the observed selective crystallization of polymorphs. This crystal engineering technique suggests that surfactant self-assemblies can be used as tailored templates for polymorphic control.

Analytical Techniques for Structural Characterization of Proteins in Solid Pharmaceutical Forms: An Overview

Therapeutic proteins as biopharmaceuticals have emerged as a very important class of drugs for the treatment of many diseases. However, they are less stable compared to conventional pharmaceuticals. Their long-term stability in solid forms, which is critical for product performance, depends heavily on the retention of the native protein structure during the lyophilization (freeze-drying) process and, thereafter, in the solid state. Indeed, the biological function of proteins is directly related to the tertiary and secondary structure. Besides physical stability and biological activity, conformational stability (three-dimensional structure) is another important aspect when dealing with protein pharmaceuticals. Moreover, denaturation as loss of higher order structure is often a precursor to aggregation or chemical instability. Careful study of the physical and chemical properties of proteins in the dried state is therefore critical during biopharmaceutical drug development to deliver a final drug product with built-in quality that is safe, high-quality, efficient, and affordable for patients. This review provides an overview of common analytical techniques suitable for characterizing pharmaceutical protein powders, providing structural, and conformational information, as well as insights into dynamics. Such information can be very useful in formulation development, where selecting the best formulation for the drug can be quite a challenge.