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

Abstract

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.

Determination of pKa Values for Some Benzimidazole and Imidazole Group Drugs Using the Reversed-Phase Liquid Chromatography Method

“…38 Only a few reports are available in the literature on the pK a values of the compound. 10,12,39 The experimentally determined pK a value of clotrimazole in this study belongs to the imidazole ring of the structure.…”

Determination of spectrophotometric protonation constant of cholinesterase inhibitors

“…Aqueous pK a values at 37 o C were predicted using experimental aqueous pK a values. These experimental and predicted aqueous pK a values were compared with pK a values given from our previous works 20,22 and the other works reported [23][24][25][26] (Table 4). In literature reports, different pK a values for the same compounds are calculated.…”

“…The calculated pK a values for galantamine are not in full consistency with that reported by Meloun and co-workers. 23 In that study, galantamine was determined in different ionic strengths and temperatures. For rivastigmine, pK a values were predicted by Hsieh and co-workers 24 and Luan and co-workers.…”

Poloxamer 407 Based Gel Formulations for Transungual Delivery of Hydrophobic Drugs: Selection and Optimization of Potential Additives

“…TBN was added to aqueous P407 solution, but this system was unable to solubilize the drug completely even at a concentration of 30% w / w P407, as shown in Figure 4 . Ethanol was used as a cosolvent because of the higher solubility of TBN (up to 45 mg/mL) [ 30 ] and P407 polymer in ethanol [ 31 ]. However, P407 gel containing 10% w / w ethanol was also incapable of loading 1% w/w of TBN ( Figure 4 ).…”