Acyclovir is the API in the most common antiviral drug used for treatment of HSV and VZV infections. Advantages for acyclovir are low cytotoxicity and low HSV resistance as well as the availability of low cost generic forms. Disadvantages include low bioavailability, perhaps partially due to low solubility. Herein, we present cocrystallization of acyclovir with ascorbic acid and zinc chloride forming a new complex. Acyclovir was separated from an acyclovir drug and the cocrystals of 1:1:1 acyclovirascorbic acid-ZnCl 2 , ACV-ASc-Zn) were screened by slow evaporation via solution-based methods under 10 solvents. Successful cocrystal forms in the solvent isopropanol-water (1:2). Physical properties were characterized by SEM/EDX, FT-IR and TGA.
The 1:1 adduct of [SnCl2(C2H4COOCH3)2] and 1,10-phenanthroline, (C12H8N2), which was set aside for 25 years, when recrystallized from ethanol was found to be the salt [C12H9N2]+.[SnCl2(C2H4COO)(C2H4COOH)]-. The Sn(IV) atom in the anion has pseudo-octahedral coordination with two cis Cl atoms, two C atoms and two O atoms trans to the Cl atoms. The possibility of alternative stacking of layers perpendicular to c* offers an explanation for observed twinning and polytypism. An ordered, untwinned, Z = 2 crystal structure was determined. Pairs of adjacent anions are linked together by strong intermolecular O-H...O- hydrogen bonds, and the cation contains a strong intramolecular N-H...N hydrogen bond between its two N atoms. The protonated ring of the cation exhibits increased Lewis acidity and is linked into a network with the anions using a strong N-H...O and weak C-H...O and C-H...Cl interactions. The remaining rings of the cation form weaker C-H...O and C-H...Cl interactions. The cations stack in columns along a with an interplanar spacing of 3.24 angstroms for separations between cations inversion-related about (1, 1/2, 1/2) and 3.34 angstroms for separations between cations inversion-related about (1/2, 1/2, 1/2).
Two systems for the formation of cocrystals of donepezil were investigated using donepezil hydrochloride and donepezil solvate with salicylic acid and p-aminobenzoic acid. The donepezil solvate was prepared through an acidbase reaction between a hydrochloride salt and a base in methanol. Donepezil HCl (DH) and the solvate with salicylic acid and p-aminobenzoic acid (PABA) at 1:1 molar ratios were prepared using the cogrinding method. Cocrystals were characterized using attenuated total reflection-FTIR spectroscopy (ATR-FTIR), nuclear magnetic resonance spectroscopy (13 C and 1 H NMR), Powder X-ray diffraction, and differential scanning calorimetry. These results indicate that the cogrinding process could induce cocrystal formation in donepezil systems through a simple process that allows for rapid screening of cocrystals of donepezil.
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