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Preparation of spherically agglomerated crystals of aminophylline

Journal of Pharmaceutical Sciences 73(10): 1407-1410
Preparation of spherically agglomerated crystals of aminophylline
The spherically agglomerated crystals of aminophylline (theophylline-ethylenediamine complex) can be compounded directly into pharmaceutical formulations without further processing, e.g., granulation. Such crystals were prepared by mixing theophylline and ethylenediamine in a partially miscible solvent system, i.e., organic solvent-ethanol-water. The organic solvents used were chloroform, 1-hexanol, isopropyl acetate, isobutyl acetate, isoamyl acetate, benzene, toluene, n-hexane or n-heptane. Spherical crystallization depended upon the solubility of theophylline in the solvent mixture. The resultant agglomerated crystals were identical with the theophylline-ethylenediamine complex by IR, X-ray and differential scanning calorimetry analyses, and was the .alpha.-, .beta.- or .gamma.-form when the water of crystallization was .ltoreq. 0.5, 1.0 and 2.5 mol, respectively. When the amount of ethylenediamine used was < 1.1 ml (0.0165 mol), the resultant agglomerated crystals were converted to anhydrous theophylline by washing with ethanol. When water was added to the system (.gtoreq. 0.3 ml, i.e., 0.0167 mol), water was occluded in the resultant agglomerates as water of crystallization. Ethylenediamine content in the agglomerated crystals could be controlled by changing the amount of ethylenediamine added in the crystallization solvent.

Accession: 006173941

PMID: 6502490

DOI: 10.1002/jps.2600731021

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