About this Research Topic
Pharmaceutical drugs are mainly formulated as crystalline solid forms due to superior purity and stability and marketed as tablets, which are easy to consume orally. Solid forms may exist as polymorphs, salts, cocrystals, hydrates, solvates, solid solutions, eutectics, amorphous phases, and more. The solid form is highly important in tuning drug properties as it impacts many variables including solubility, permeability, bioavailability, tabletability, and physical/chemical stability. Controlling solid forms via nucleation and tuning pharmaceutically relevant properties are highly challenging and difficult to predict areas. Therefore, designing next generation pharmaceutical cocrystals including drug-drug binary/ternary cocrystals and eutectic solid forms using a crystal engineering approach may be a vital tool in solving problems of tunability and the optimization of desirable properties in pharmaceutical solid forms.
Currently, eight drug-based cocrystals are commercially available and four promising cocrystals are under clinical trials, with many more cocrystals on the pipeline in drug development stages. Here, we would like to choose Biopharmaceutics Classification System (BCS) class II, III and IV with either solubility/permeability problems and transform to BCS class I with improved solubility and permeability using a cocrystal engineering approach. One example of the challenges faced is that many of the drugs are of brittle nature in their native forms and need an excipient as a binder to make compressible tablets. A crystal engineering approach can be utilized to make compressible tablets in the native form itself. In conclusion, solid state chemistry has an important role in tuning varieties of solid forms that alter crystal packing arrangement and hence drug properties.
In this Research Topic, we would like to highlight recent developments in tuning drug properties using engineering of solid forms. Themes to be addressed include, but are not limited to:
• Novel polymorphs, hydrates, solvates of new or marketed drugs
• Pharmaceutical cocrystals and salts in tuning drug properties
• Drug-drug binary/ternary or higher order cocrystals with improved properties including clinical efficacy.
• Structure-property correlation among the new solid forms.
• Novel drug eutectic solid forms and solid solutions
• Crystal structure solution from high resolution PXRD.
Keywords: Crystal engineering, pharmaceutical cocrystals, polymorphs, eutectics, drug properties
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