Hydrates, salt solid-state properties

Besides regulatory importance, salts, polymorphs, and hydrates/solvates have clear novelty and patentability considering their different chemical compositions or distinguishable solid state ( fon Raumer et al., 2006). Those new forms can affect not only their processibilities, such as crystallization,Lltration, and compression, but also their biological properties, such as solubility and bioavailability. Besides, the manufacturing processes for those forms are often innovative, and thus patentable. 

The properties of the aqua-ions [Fe(H20)6] " and [Fe(H20)6] + in solution have been placed in context and reviewed in detail. Their structures, estabhshed in the solid state in several X-ray diffraction studies of hydrated iron(ll) and iron(lll) salts, have been investigated in solution by... 

Compounds of pharmaceutical interest can exist in different solid forms. Broadly, they can be classified as being in the amorphous or in the crystalline state. In crystalline pharmaceuticals, solvates are formed when the solvent molecule is incorporated, either stoichiometrically or non-stoichiometrically, in the crystalline lattice. Hydrates are a subclass of solvates, wherein the incorporated solvent is water. Because of regulatory considerations, non-aqueous solvates find limited use as pharmaceuticals. Our dis-cu.ssions will, therefore, be restricted to hydrates. If the solvent is non-volatile, co-crystals are obtained, and this is an emerging field in solid-state pharmaceutics. In case of weakly acidic and basic compounds, salt forms are prepared with the goal of obtaining the desired biopharmaceutical properties. Figure 3 is a schematic representation of the various types of solid forms of interest in pharmaceuticals (6). 

It has been found that (S)-4-[[[l-(4-fluorophenyl)-3-(l-methyl-ethyl)-lH-indol-2-yl]-ethynyl]-hydroxyphosphinyl]-3]-hydroxybutanoic acid, disodium salt, is capable of existing in three crystalline hydrate and one liquid crystalline phase depending on the relative humidity to which the compound is exposed [58]. Among other things, these have been found to exhibit varying fluorescence properties in their respective solid states [59]. As shown in Fig. 4, the particle morphology of these... 

Salts, and more recently co-crystals, have attracted much interest in the pharmaceutical industry for their promise in tailoring the physical properties of an active pharmaceutical ingredient (API) to meet the needs of the drug product and ultimately the patient.Salt forms, produced by add (A)-base (B) reactions in the solid state, are multi-component solids comprising minimally an A B pair they may be crystalline or amorphous. The term co-crystal, on the other hand, refers specifically to crystalline molecular complexes, which may include an A B pair among the different components and by definition necessarily include solvates (hydrates), inclusion compounds, clathrates and solid solutions. 

Although selenic and telluric acids contain the central atom in the +6 oxidation state, they are very different. The properties of selenic acid, H2Se04, are very similar to those of H2S04, and many of their salts are similar. The oxyacid that contains Te in the +6 state is HsTeOs which can also be written as Te(OH)s. This acid can be prepared from Te or Te02 by suitable oxidation reactions, and it can be also obtained as a solid hydrate. As expected from the formula, telluric acid is a weak acid, although some salts can be obtained in which one or more protons are replaced. 

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