Thermodynamic analysis of the solubility of propranolol-HCl in ethanol + water mixtures

Propranolol-HCl (PPN-HCl) is a non selective β-adrenergic blocker widely used in therapeutics. Nevertheless, their physicochemical properties in aqueous media have not been adequately studied. In this context, by using the van't Hoff and Gibbs equations the thermodynamic functions Gibbs energy, enthalpy, and entropy of solution for this drug in ethanol (EtOH) + water (W) cosolvent mixtures, were evaluated from solubility data determined at several temperatures. The solubility was the greatest in the mixtures with 0.60 or 0.70 in mass fraction of EtOH and the lowest in neat W (or neat EtOH, as well) at almost all the temperatures studied. This behavior shows the cosolvent effect present for this electrolyte drug in this solvent system. By means of enthalpy-entropy compensation analysis, non-linear ΔH soln 0-app vs. ΔG soln 0-app plot with negative slope from water up to 0.10 in mass fraction of EtOH and positive slope from 0.10 to 0.60 in mass fraction of EtOH. Accordingly to this result, it follows that the dominant mechanism for the solubility of PPN-HCl in water-rich mixtures is the entropy, probably due to water-structure loosing around the drug's non-polar moieties by EtOH molecules, whereas, between 0.10 and 0.60 in mass fraction of EtOH the dominant mechanism is the enthalpy probably due to drug solvation increase by EtOH molecules. Ultimately, beyond this composition the behavior was more complex, and therefore, the ionic and molecular events involved in the drug dissolution in ethanol-rich mixtures are unclear.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Thermodynamic analysis of the solubility of propranolol-HCl in ethanol + water mixtures

Propranolol-HCl (PPN-HCl) is a non selective β-adrenergic blocker widely used in therapeutics. Nevertheless, their physicochemical properties in aqueous media have not been adequately studied. In this context, by using the van't Hoff and Gibbs equations the thermodynamic functions Gibbs energy, enthalpy, and entropy of solution for this drug in ethanol (EtOH) + water (W) cosolvent mixtures, were evaluated from solubility data determined at several temperatures. The solubility was the greatest in the mixtures with 0.60 or 0.70 in mass fraction of EtOH and the lowest in neat W (or neat EtOH, as well) at almost all the temperatures studied. This behavior shows the cosolvent effect present for this electrolyte drug in this solvent system. By means of enthalpy-entropy compensation analysis, non-linear ΔH soln 0-app vs. ΔG soln 0-app plot with negative slope from water up to 0.10 in mass fraction of EtOH and positive slope from 0.10 to 0.60 in mass fraction of EtOH. Accordingly to this result, it follows that the dominant mechanism for the solubility of PPN-HCl in water-rich mixtures is the entropy, probably due to water-structure loosing around the drug's non-polar moieties by EtOH molecules, whereas, between 0.10 and 0.60 in mass fraction of EtOH the dominant mechanism is the enthalpy probably due to drug solvation increase by EtOH molecules. Ultimately, beyond this composition the behavior was more complex, and therefore, the ionic and molecular events involved in the drug dissolution in ethanol-rich mixtures are unclear.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Solution Thermodynamics of Lysine Clonixinate in Some Ethanol + Water Mixtures

The solubility of lysine clonixinate (LysClon) in several ethanol + water mixtures was determined at 293.15 to 313.15 K. The thermodynamic functions, Gibbs energy, enthalpy, and entropy of solution and of mixing were obtained from these solubility data by using the van’t Hoff and Gibbs equations. In general this drug exhibit good solubility and the greatest value was obtained in the mixture 0.60 in mass fraction of ethanol. A non-linear enthalpy–entropy relationship was observed from a plot of enthalpy vs. Gibbs energy of solution. Accordingly, the driving mechanism for LysClon solubility in water-rich and ethanol-rich mixtures is the entropy, probably due to water-structure losing around the drug non-polar moieties by ethanol or increased ionic solvation; whereas, in the medium composition mixtures the driving mechanism is the enthalpy, probably due to LysClon solvation increase by the co-solvent molecules.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Solution Thermodynamics of Lysine Clonixinate in Some Ethanol + Water Mixtures

The solubility of lysine clonixinate (LysClon) in several ethanol + water mixtures was determined at 293.15 to 313.15 K. The thermodynamic functions, Gibbs energy, enthalpy, and entropy of solution and of mixing were obtained from these solubility data by using the van’t Hoff and Gibbs equations. In general this drug exhibit good solubility and the greatest value was obtained in the mixture 0.60 in mass fraction of ethanol. A non-linear enthalpy–entropy relationship was observed from a plot of enthalpy vs. Gibbs energy of solution. Accordingly, the driving mechanism for LysClon solubility in water-rich and ethanol-rich mixtures is the entropy, probably due to water-structure losing around the drug non-polar moieties by ethanol or increased ionic solvation; whereas, in the medium composition mixtures the driving mechanism is the enthalpy, probably due to LysClon solvation increase by the co-solvent molecules.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Preferential Solvation of the Antioxidant Agent Daidzein in some Aqueous Co-Solvent Mixtures according to IKBI and QLQC Methods

The preferential solvation parameters by ethanol (EtOH) or propylene glycol (PG) of daidzein were derived from their solution thermodynamic properties by means of the inverse Kirkwood-Buff integrals and the quasi-lattice-quasi-chemical (QLQC) methods. According to IKBI method, the preferential solvation parameter by the co-solvent, δx1,3, is negative in water-rich mixtures but positive in co-solvent-rich mixtures in both kinds of systems. This could demonstrate the relevant role of hydrophobic hydration around the aromatic rings in the drug solvation in water-rich mixtures. Furthermore, the more solvation by co-solvent in co-solvent-rich mixtures could be due mainly to polarity effects and acidic behavior of the hydroxyl groups of the compound in front to the more basic solvents present in the mixtures, i.e. EtOH or PG. Otherwise, according to QLQC method, this drug is preferentially solvated by the co-solvents in all the mixtures in both kind of systems

Continued Evaluation of Gear Condition Indicator Performance on Rotorcraft Fleet

This paper details analyses of condition indicator performance for the helicopter nose gearbox within the U.S. Army's Condition-Based Maintenance Program. Ten nose gearbox data sets underwent two specific analyses. A mean condition indicator level analysis was performed where condition indicator performance was based on a 'batting average' measured before and after part replacement. Two specific condition indicators, Diagnostic Algorithm 1 and Sideband Index, were found to perform well for the data sets studied. A condition indicator versus gear wear analysis was also performed, where gear wear photographs and descriptions from Army tear-down analyses were categorized based on ANSI/AGMA 1010-E95 standards. Seven nose gearbox data sets were analyzed and correlated with condition indicators Diagnostic Algorithm 1 and Sideband Index. Both were found to be most responsive to gear wear cases of micropitting and spalling. Input pinion nose gear box condition indicators were found to be more responsive to part replacement during overhaul than their corresponding output gear nose gear box condition indicators

Thermodynamic analysis of the solubility of propranolol-HCl in ethanol + water mixtures

Propranolol-HCl (PPN-HCl) is a non selective β-adrenergic blocker widely used in therapeutics. Nevertheless, their physicochemical properties in aqueous media have not been adequately studied. In this context, by using the van't Hoff and Gibbs equations the thermodynamic functions Gibbs energy, enthalpy, and entropy of solution for this drug in ethanol (EtOH) + water (W) cosolvent mixtures, were evaluated from solubility data determined at several temperatures. The solubility was the greatest in the mixtures with 0.60 or 0.70 in mass fraction of EtOH and the lowest in neat W (or neat EtOH, as well) at almost all the temperatures studied. This behavior shows the cosolvent effect present for this electrolyte drug in this solvent system. By means of enthalpy-entropy compensation analysis, non-linear ΔH soln 0-app vs. ΔG soln 0-app plot with negative slope from water up to 0.10 in mass fraction of EtOH and positive slope from 0.10 to 0.60 in mass fraction of EtOH. Accordingly to this result, it follows that the dominant mechanism for the solubility of PPN-HCl in water-rich mixtures is the entropy, probably due to water-structure loosing around the drug's non-polar moieties by EtOH molecules, whereas, between 0.10 and 0.60 in mass fraction of EtOH the dominant mechanism is the enthalpy probably due to drug solvation increase by EtOH molecules. Ultimately, beyond this composition the behavior was more complex, and therefore, the ionic and molecular events involved in the drug dissolution in ethanol-rich mixtures are unclear.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Indomethacin solubility in propylene glycol + water mixtures according to the extended hildebrand solubility approach

In this work the Extended Hildebrand Solubility Approach (EHSA) was applied to evaluate the solubility of the analgesic drug indomethacin in propylene glycol + water mixtures at 298.15 K. An acceptable correlative capacity of EHSA was found using a regular polynomial model in order four (overall deviation lower than 2.2 %), when the W interaction parameter is related to the solubility parameter of the mixtures. Nevertheless, the deviations obtained in the estimated solubility with respect to experimental solubility were similar to those obtained directly by means of an empiric regression of the experimental solubility as a function of the mixtures’ solubility parameters.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Thermodynamics of sulfanilamide solubility in propylene glycol + water mixtures

The solubility of sulfanilamide (SA) in propylene glycol + water cosolvent mixtures was determined at temperatures from 293.15 to 313.15 K. The thermodynamic functions: Gibbs energy, enthalpy, and entropy of solution and mixing were obtained from these solubility data by using the van’t Hoff and Gibbs equations. The solubility was maximal in propylene glycol and very low in water at all the temperatures. A non linear enthalpy–entropy relationship was observed from a plot of enthalpy vs. Gibbs energy of solution. The maximum point in plot of ΔsolnH° vs. ΔsolnnG° (0.20 mass fraction of propylene glycol) separates two different trends, one with negative slope from water up to 0.20 mass fraction of propylene glycol and the other one positive beyond this composition up to propylene glycol. Accordingly, the driving mechanism for SA solubility in water-rich mixtures is the entropy, probably due to water-structure loss around the drug non-polar moieties by propylene glycol, whereas, above 0.20 mass fraction of propylene glycol the driving mechanism is the enthalpy, probably due to SA solvation increase by the co-solvent molecules.Colegio de Farmacéuticos de la Provincia de Buenos Aire