Differential scanning calorimetry studies on urea-carboxylic acid inclusion complexes

Ahmad, Jamal; Freestone, Alan J.; Hussain, Ali Athar

doi:10.1007/bf00705815

Cited by 5 publications

(1 citation statement)

References 11 publications

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“…The thermogram of the inclusion compound does not show a peak in this region, implying inclusion of the drug into the urea lattice. Further, the thermogram exhibits two endothermic events, a characteristic of the hexagonal form of complexed urea (McAdie 1962;Ahmad et al 1994). The first step involves the collapse of the hexagonal form of the urea inclusion compound to yield the guest moiety and tetragonal solid urea, while the second step involves melting of tetragonal urea.…”

Section: Characterization Of Urea Inclusion Compoundsmentioning

confidence: 99%

Urea inclusion compounds of enalapril maleate for the improvement of pharmaceutical characteristics

Thakral

Мадан

2007

Journal of Pharmacy and Pharmacology

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Urea is a well known adductor for linear organic compounds. In the present study, enalapril maleate, a substituted cyclic organic compound, was successfully included in urea together with a suitable rapidly adductible endocyte (RAE). Formation of the urea inclusion compound was confirmed by Fourier transform infrared spectroscopy, differential scanning calorimetry and X-ray diffraction. The modified Zimmerschied calorimetric method was used to estimate the minimum amount of RAE required for adduction of enalapril maleate in urea. Urea-enalapril maleate-RAE inclusion compounds containing varying proportions of guests were prepared and their thermal behaviour studied by differential scanning calorimetry. Regression analysis revealed an excellent r(2) value with regard to the influence of the relative proportion of RAE on the heat of decomposition. The inclusion compounds were found to exhibit good content uniformity and improved dissolution profile as demonstrated by increased dissolution efficiency. Studies revealed that urea inclusion may be a promising alternative for the formulation of potent poorly soluble drugs into immediate release products.

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Section: Characterization Of Urea Inclusion Compoundsmentioning

confidence: 99%