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 energ...
Guardado en:
| Autores principales: | , |
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| Formato: | Articulo |
| Lenguaje: | Inglés |
| Publicado: |
2011
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| Materias: | |
| Acceso en línea: | http://sedici.unlp.edu.ar/handle/10915/8105 http://www.latamjpharm.org/resumenes/30/1/LAJOP_30_1_1_13.pdf |
| Aporte de: |
| Sumario: | 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
<sub>soln</sub>
<sup>0-app</sup> vs.
ΔG
<sub>soln</sub>
<sup>0-app</sup> 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. |
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