Nedocromil metal salts hydration

Zhu H, Khankari RK. Padden BE, et al. Physicochemical characterization of nedocromil bivalent metal salt hydrates. 1, Nedocromil magnesium J Pharm Sci 1996 85 1026-34. 

When the solvate happens to be water, these are called hydrates, wherein water is entrapped through hydrogen bonding inside the crystal, and strengthens the crystal structure, thereby invariably reducing the dissolution rate (Table 4). The water molecules can reside in the crystal either as isolate lattice, where they are not in contact with each other as lattice channel water, where they fill space and metal coordinated water in salts of weak acids, where the metal ion coordinates with the water molecule. Metal ion coordinates may also fill channels, such as in the case of nedocromil sodium trihydrate. Crystalline hydrates have been classified by structural aspects into three classes isolated lattice sites, lattice channels, and metal-ion coordinated water. There are three classes, which are discernible by the commonly available analytical techniques. 

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