The thermodynamic dissociation constants of four non-steroidal anti-inflammatory drugs by the least-squares nonlinear regression of multiwavelength spectrophotometric pH-titration data

Meloun, Milan; Bordovská, Sylva; Galla, Lubomír

doi:10.1016/j.jpba.2007.07.029

Cited by 97 publications

(73 citation statements)

References 62 publications

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“…Lachema Brno) were not further purified. The preparation of other solutions from analytical reagent-grade chemicals has been described previously [37][38][39][40].…”

Section: Methodsmentioning

confidence: 99%

“…The apparatus used and the pH-spectrophotometric titration procedure described in [37][38][39][40] were applied. The microscale pH-titrimetric method generally decreases the amount of drug sample required but the duration of experiment is as long as that of a conventional titration.…”

Section: Apparatus and Procedurementioning

confidence: 99%

“…The computation scheme for the determination of the protonation constants of the multicomponent system is taken from Meloun et al, cf. [1, page 226] and the five steps are described elsewhere [37][38][39][40][44][45][46][47][48]: (1) instrumental error of absorbance measurements, s inst (A), (2) experimental design, (3) number of light-absorbing species with a factor analysis, (4) choice of computational strategy of the nonlinear regression, (5) diagnostics indicating a correct chemical (protonation) model: when a minimization process terminates, some curve-fitting diagnostics are examined to determine whether the results should be accepted: the physical meaning of parametric estimates, the physical meaning of the species concentrations, the goodness-offit test of spectra calculated, and the deconvolution of the experimental spectra set.…”

Section: Apparatus and Procedurementioning

confidence: 99%

“…The procedure for the determination of the mixed protonation/dissociation constants has been described previously [37][38][39][40]. The details of the computer data treatment are collected in the Supporting Information.…”

Section: Introductionmentioning

confidence: 99%

“…, m, may be examined by a goodness-of-fit test, cf. a previous tutorial [37][38][39][40]. Repeatability and reproducibility (R&R) are critical factors closely related to precision and accuracy.…”

Section: Introductionmentioning

confidence: 99%

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The Thermodynamic Dissociation Constants of Clotrimazole, Terbinafine HCL, Acetylsalicylic Acid, Salicylic Acid, and Galanthamine by the Nonlinear Regression of Multiwavelength Spectrophotometric pH-Titration Data

2010

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The mixed dissociation constants of five drugs-clotrimazole, terbinafine HCl, acetylsalicylic acid, salicylic acid, and galanthamineat various ionic strengths I and at temperatures of 25 • C and 37 • C were determined with the use of multiwavelength and multivariate treatments of spectral data SPECFIT/32 nonlinear regression analysis and INDICES factor analysis. The factor analysis in the INDICES program predicts the number of components, when the data quality is high and the instrumental error is known. The thermodynamic dissociation constant pK T a was estimated by nonlinear regression of {pK a, I} data at 25 • C and 37 • C: for clotrimazole pK T a,1 = 4.38(1) and 4.16(3); for terbinafine HCl pK T a,1 = 4.19(3) and 4.12(5); for acetylsalicylic acid pK T a,1 = 3.49(25) and 3.41(15); for salicylic acid pK T a,1 = 3.01(1) and 3.00(1) and for galanthamine pK T a,1 = 8.21(1) and 7.99(2) where in brackets the standard deviation is in the last significant digits. Goodness-of-fit tests for various regression diagnostics enabled the reliability of the parameter estimates found to be proven. Pharma Algorithms predicts pK a being based on the structural formulae of drug compounds.

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“…Lachema Brno) were not further purified. The preparation of other solutions from analytical reagent-grade chemicals has been described previously [37][38][39][40].…”

Section: Methodsmentioning

confidence: 99%