Processing of ketoconazole–4-aminobenzoic acid cocrystals using dense CO 2 as an antisolvent

Controlling the Polymorphism of Indomethacin with Poloxamer 407 in a Gas Antisolvent Crystallization Process

The polymorphic control of active pharmaceutical ingredients (APIs) is a major challenge in the manufacture of medicines. Crystallization methods that use supercritical carbon dioxide as an antisolvent can create unique solid forms of APIs, with a particular tendency to generate metastable polymorphic forms. In this work, the effects of processing conditions within a gas antisolvent (GAS) crystallization method, such as pressure, stirring rate, and temperature, as well as the type of solvent used and the presence of an additive, on the polymorphism of indomethacin were studied. Consistent formation of the X-ray powder diffraction-pure α polymorphic form of indomethacin by GAS was only achieved when a polymer, poloxamer 407, was used as an additive. Using the GAS method in combination with poloxamer 407 as a molecular additive enabled full control over the polymorphic form of indomethacin, regardless of the processing conditions employed, such as pressure, temperature, stirring rate, and type of solvent. A detailed molecular modeling study provided insight into the role of poloxamer 407 in the polymorphic outcome of indomethacin and concluded that it favored the formation of the α polymorph.

Curcumin and n-acetylcysteine cocrystal produced with supercritical solvent: characterization, solubility, and preclinical evaluation of antinociceptive and anti-inflammatory activities

Curcumin presents a promising anti-inflammatory potential, but its low water-solubility and bioavailability hinder its application. In this sense, cocrystallization represents a tool for improving physicochemical properties, solubility, permeability, and bioavailability of new drug candidates. Thus, the aim of this work was to produce curcumin cocrystals (with n-acetylcysteine as coformer, which possesses anti-inflammatory and antioxidant activities), by the anti-solvent gas technique using supercritical carbon dioxide, and to test its antinociceptive and anti-inflammatory potential. The cocrystal was characterized by differential scanning calorimetry, powder X-ray diffraction and scanning electron microscopy. The cocrystal solubility and antichemotaxic activity were also assessed in vitro. Antinociceptive and anti-inflammatory activities were carried out in vivo using the acetic acid-induced abdominal writhing and carrageenan-induced paw oedema assays in mice. The results demonstrated the formation of a new crystalline structure, thereby confirming the successful formation of the cocrystal. The higher solubility of the cocrystal compared to pure curcumin was verified in acidic and neutral pH, and the cocrystal inhibited the chemotaxis of neutrophils in vitro. In vivo assays showed that cocrystal presents increased antinociceptive and anti-inflammatory potency when compared to pure curcumin, which could be related to an improvement in its bioavailability.

Ketoconazole-p-aminobenzoic Acid Cocrystal: Revival of an Old Drug by Crystal Engineering

The 1:1 cocrystal of the antifungal agent ketoconazole with p-aminobenzoic acid was successfully crystallized and systematically characterized by a physical and pharmacological point of view. Crystal structure determination confirmed the cocrystal identity, giving full insight in its crystal packing and degree of disorder. Powder dissolution measurements revealed a 10-fold aqueous solubility increase that induces a 6.7-fold oral bioavailability improvement compared to ketoconazole. In vitro cell assays showed a good toxicity profile of the cocrystal with lower oxidative stress and inflammation and enhanced antifungal activity against several Candida species. The in vivo study of the cocrystal indicated similar pharmacokinetic profiles and liver toxicity with increased transaminases, as reported for ketoconazole. Notably, besides minor signs of inflammation, no morphological changes in liver parenchyma or signs of fibrosis and necrosis were detected. The enhanced solubility and oral bioavailability of the cocrystal over ketoconazole, together with the improved antifungal activity and good in vitro/in vivo toxicity, indicate its potential use as an alternative antifungal agent to the parent drug. Our results bring evidence of cocrystallization as a successful approach for bioavailability improvement of poorly soluble drugs.

Continuous manufacturing of co-crystals: challenges and prospects

The last decade has witnessed extensive growth in the field of co-crystallization for mitigating the solubility and dissolution-related issues of poorly soluble drugs. This is largely because co-crystals can modify the physicochemical properties of drugs without any covalent modification in the drug molecules. The US Food and Drug Administration (FDA) now considers drug products that are designed to contain a new co-crystal, analogous to new polymorph of the active pharmaceutical ingredient (API). This positive change in regulatory perspective coupled with successful commercialization of valsartan-sacubitril co-crystal (Entresto, Novartis) has now brought co-crystals into focus, in both industries as well as academia. Co-crystal prediction, screening, and synthesis have been reported in literature; however, co-crystal production at a larger scale needs further investigations. With this aim, the article describes various continuous methods for co-crystal production, along with in-line monitoring during co-crystal production, emphasizing on process analytical technology (PAT). In addition, the scale-up issues of continuous and batch co-crystallization and other suitable techniques for pharmaceutical scale up are detailed. Quality control aspects and regulatory viewpoint crucial for commercial success are elaborated in the future perspective.