On the role of solvent in acid–base equilibria of diuretics in acetonitrile–water mixed solvents

The dissociation constants of representative loop (furosemide), thiazide (chlorthiazide and trichlormethiazide) and potassium sparing (amiloride) diuretics in 10, 30, 40, 50 and 70% (w/w) acetonitrile–water mixtures at 298.15 K were determined, in accordance with IUPAC procedures. The variation in p...

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Bibliographic Details
Published in:Talanta (Oxford) 1998-03, Vol.45 (5), p.817-827
Main Authors: Barbosa, J., Barrón, D., Beltrán, J.L., Butı́, S.
Format: Article
Language:English
Subjects:
Acetonitrile–water mixtures
Biological and medical sciences
Diuretics
General pharmacology
Linear solvation energy relationship
Medical sciences
p K values
Pharmacology. Drug treatments
Physicochemical properties. Structure-activity relationships
Preferential solvation
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Summary:The dissociation constants of representative loop (furosemide), thiazide (chlorthiazide and trichlormethiazide) and potassium sparing (amiloride) diuretics in 10, 30, 40, 50 and 70% (w/w) acetonitrile–water mixtures at 298.15 K were determined, in accordance with IUPAC procedures. The variation in p K a values over the whole composition range can be explained by preferential solvation and the structural features in acetonitrile–water mixtures. Correlations between p K a values and various bulk and solvatochromic properties of the solvents were calculated. The linear solvation energy relationship (LSER) method was applied. The resulting equations allowed us to calculate p K a values for the diuretics studied in any acetonitrile–water mixture up to 70% (w/w) and should help to clarify the acid–base behaviour of diuretics in the widely-used acetonitrile–water mixed solvents.
ISSN:0039-9140
1873-3573
DOI:10.1016/S0039-9140(97)00167-7