Antisolvent crystallization of pharmaceutical excipients from aqueous solutions and the use of preferred orientation in phase identification by powder X-ray diffraction

Paclitaxel Drug Delivery Systems: Focus on Nanocrystals' Surface Modifications

Paclitaxel (PTX) is a chemotherapeutic agent that belongs to the taxane family and which was approved to treat various kinds of cancers including breast cancer, ovarian cancer, advanced non-small-cell lung cancer, and acquired immunodeficiency syndrome (AIDS)-related Kaposi’s sarcoma. Several delivery systems for PTX have been developed to enhance its solubility and pharmacological properties involving liposomes, nanoparticles, microparticles, micelles, cosolvent methods, and the complexation with cyclodextrins and other materials that are summarized in this article. Specifically, this review discusses deeply the developed paclitaxel nanocrystal formulations. As PTX is a hydrophobic drug with inferior water solubility properties, which are improved a lot by nanocrystal formulation. Based on that, many studies employed nano-crystallization techniques not only to improve the oral delivery of PTX, but IV, intraperitoneal (IP), and local and intertumoral delivery systems were also developed. Additionally, superior and interesting properties of PTX NCs were achieved by performing additional modifications to the NCs, such as stabilization with surfactants and coating with polymers. This review summarizes these delivery systems by shedding light on their route of administration, the methods used in the preparation and modifications, the in vitro or in vivo models used, and the advantages obtained based on the developed formulations.

Application of Fundamental Techniques for Physicochemical Characterizations to Understand Post-Formulation Performance of Pharmaceutical Nanocrystalline Materials

Nanocrystalline materials (NCM, i.e., crystalline nanoparticles) have become an important class of materials with great potential for applications ranging from drug delivery and electronics to optics. Drug nanocrystals (NC) and nano co-crystals (NCC) are examples of NCM with fascinating physicochemical properties and have attracted significant attention in drug delivery. NCM are categorized by advantageous properties, such as high drug-loading efficiency, good long-term physical stability, steady and predictable drug release, and long systemic circulation time. These properties make them excellent formulations for the efficient delivery of a variety of active pharmaceutical ingredients (API). In this review, we summarize the recent advances in drug NCM-based therapy options. Currently, there are three main methods to synthesize drug NCM, including top-down, bottom-up, and combination methods. The fundamental characterization methods of drug NCM are elaborated. Furthermore, the applications of these characterizations and their implications on the post-formulation performance of NCM are introduced.

It is Possible to Achieve Tablets With Good Tabletability From Solid Dispersions - The Case of the High Dose Drug Gemfibrozil

BACKGROUND

Solid Dispersions (SDs) have been extensively used to increase the dissolution of poorly water-soluble drugs. However, there are few studies exploring SDs properties that must be considered during tablet development, like tabletability. Poorly water-soluble drugs with poor compression properties and high therapeutic doses, like gemfibrozil, are an additional challenge in the production of SDs-based tablets.

OBJECTIVE

This study evaluates the applicability of SDs to improve both tabletability and dissolution rate of gemfibrozil. A SD-based tablet formulation was also proposed.

METHODS

SDs were prepared by ball milling, using hydroxypropyl methylcellulose (HPMC) as a carrier, according to a 2³ factorial design. The formulation variables were gemfibrozil:HPMC ratio, milling speed, and milling time. The response in the factorial analysis was the tensile strength of the compacted SDs. Dissolution rate and solid-state characterization of SDs were also performed.

RESULTS

SDs showed simultaneous drug dissolution enhancement and improved tabletability when compared to corresponding physical mixtures and gemfibrozil. The main variable influencing drug dissolution and tabletability was the gemfibrozil:HPMC ratio. Tablets containing gemfibrozil- HPMC-SD (1:0.250 w/w) and croscarmellose sodium showed fast and complete drug release, while those containing the same SD and sodium starch glycolate exhibited poor drug release due to their prolonged disintegration time.

CONCLUSION

SDs proved to be effective for simultaneously improving tabletability and dissolution profile of gemfibrozil. Tablets containing gemfibrozil-HPMC-SD and croscarmellose sodium as disintegrating agent showed improved drug release and good mechanical strength, demonstrating the potential of HPMC-based SDs to simultaneously overcome the poor dissolution and tabletability properties of this drug.

Investigations in physical mechanism of ultrasound-assisted antisolvent batch crystallization of lactose monohydrate from aqueous solutions

Sonication is known to enhance crystallization of lactose from aqueous solutions. This study has attempted to reveal the mechanistic features of antisolvent crystallization of lactose monohydrate from aqueous solutions. Experiments were conducted in three protocols, viz. mechanical stirring, mechanical stirring with sonication and sonication at elevated static pressure. Mechanical stirring provided macroconvection while sonication induced microconvection in the system. Other experimental parameters were initial lactose concentration and rate of antisolvent (ethanol) addition. Kinetic parameters of crystallization were coupled with simulations of bubble dynamics. The growth rate of crystals, rate of nucleation, average size of crystal crop and total lactose yield in different protocols were related to nature of convection in the medium. Macroconvection assisted nucleation but could not give high growth rate. Microconvection comprised of microstreaming due to ultrasound and acoustic (or shock) waves due to transient cavitation. Sonication at atmospheric static pressure enhanced growth rate but reduced nucleation. However, with elimination of cavitation at elevated static pressure, sonication enhanced both nucleation and growth rate resulting in almost complete lactose recovery.

Imagine the Superiority of Dry Powder Inhalers from Carrier Engineering

Inhalation therapy has strong history of more than 4000 years and it is well recognized around the globe within every culture. In early days, inhalation therapy was designed for treatment of local disorders such as asthma and other pulmonary diseases. Almost all inhalation products composed a simple formulation of a carrier, usually α-lactose monohydrate orderly mixed with micronized therapeutic agent. Most of these formulations lacked satisfactory pulmonary deposition and dispersion. Thus, various alternative carrier's molecules and powder processing techniques are increasingly investigated to achieve suitable aerodynamic performance. In view of this fact, more suitable and economic alternative carrier's molecules with advanced formulation strategies are discussed in the present review. Furthermore, major advances, challenges, and the future perspective are discussed.

In Situ Growth and Wrapping of Aminoanthraquinone Nanowires in 3 D Graphene Framework as Foldable Organic Cathode for Lithium-Ion Batteries

Small conjugated carbonyl compounds are intriguing candidates for organic electrode materials because of their abundance, high theoretical capacity, and adjustable molecular structure. However, their dissolution in aprotic electrolytes and poor conductivity eclipse them in terms of practical capacity, cycle life, and rate capability. Herein, we report a foldable and binder-free nanocomposite electrode consisting of 2-aminoanthraquinone (AAQ) nanowires wrapped within the 3 D graphene framework, which is prepared through antisolvent crystallization followed by a facile chemical reduction and selfassembly process. The nanocomposite exhibited a very high capacity of 265 mA h g^-1 at 0.1 C for AAQ, realizing 100 % utilization of active material. Furthermore, the nanocomposite shows superior cycling stability (82 % capacity retention after 200 cycles at 0.2 C and 76 % capacity retention after 1000 cycles at 0.4 C) and excellent rate performance (153 mA h g^-1 at 5 C). Particularly, the nanocomposite can deliver the highest capacity of 165 mA h g^-1 among all reported anthraquinone- and anthraquinone-analogues-based electrodes per mass of the whole electrode, which is essential for practical application. Such outstanding electrochemical performance could be largely attributed to the wrapping structure of the flexible composite, which provides both conductivity and structural integrity.

The role of a mixture of DMSO : water in the crystallization of α-lactose monohydrate (α-LM) single crystals with desired morphology

In this study, DMSO–water solvent mixtures (from 10 to 90% v/v) were used for the growth of alpha-lactose monohydrate (α-LM) single crystals.

Uniform amorphous lactose microspheres formed in simultaneous convective and dehydration antisolvent precipitation under atmospheric conditions

A simultaneous convection-dehydration and antisolvent precipitation approach has been shown to produce uniform microsized lactose particles from aqueous droplet at atmospheric pressure. Microparticles with high uniformity having diameters of between 1.0 and 2.4 μm have been obtained. The precipitation of the microparticles is driven by a unique self-assembly mechanism that cannot be fully elucidated by supersaturation alone. Further analysis suggests that structural changes in the solvent/antisolvent mixture, due to hydrophobic hydration, could play a role in the precipitation process observed.