Please use this identifier to cite or link to this item:
Title: Caffeine and nicotinamide enhances the aqueous solubility of the antimalarial agent halofantrine
Authors: Lim, L.-Y. 
Go, M.-L. 
Keywords: 1H NMR
Differential scanning calorimetry
Phase solubility studies
Issue Date: Mar-2000
Citation: Lim, L.-Y., Go, M.-L. (2000-03). Caffeine and nicotinamide enhances the aqueous solubility of the antimalarial agent halofantrine. European Journal of Pharmaceutical Sciences 10 (1) : 17-28. ScholarBank@NUS Repository.
Abstract: The aqueous solubility of the antimalarial agent halofantrine in phosphate buffers pH 5.9 and 7.0 (ionic strength 0.08) is increased by the addition of caffeine and nicotinamide. Solubility is increased to a greater extent in the presence of caffeine (12.5-125 mM) than nicotinamide (125 mM - 2.0 M). The greatest increase in solubility was observed at pH 5.9 where the basal solubility of halofantrine rose from 0.91 to 435 μM when 125 mM caffeine was added. Phase solubility studies support the formation of a 1:1 complex between caffeine and halofantrine which is characterised by a K(1:1) constant of 2.75 x 103 M-1 (pH 5.9). A less stable 1:1 complex is formed at pH 7.0 (K(1:1)=6.37 x 103 M-1). Differential scanning calorimetry of solid mixtures of caffeine and halofantrine showed the absence of the endotherms of the two drugs and the appearance of a distinct endotherm (with a smaller enthalpy) characteristic of the complex. An analysis of the 1H-NMR spectra of mixtures of caffeine and halofantrine revealed perturbations in the chemical shifts of the methyl group and proton at positions 4 and 8 of caffeine, and a change in splitting pattern of the H9 proton of the phenanthrene ring in halofantrine. (C) 2000 Elsevier Science B.V.
Source Title: European Journal of Pharmaceutical Sciences
ISSN: 09280987
DOI: 10.1016/S0928-0987(99)00084-6
Appears in Collections:Staff Publications

Show full item record
Files in This Item:
There are no files associated with this item.


checked on Sep 25, 2020


checked on Sep 17, 2020

Page view(s)

checked on Sep 26, 2020

Google ScholarTM



Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.