HPLC and solubility study of the interaction between pindolol and cyclodextrins.
The complexation with beta-cyclodextrin (beta-CD) has been investigated using reversed-phase liquid chromatography. The compounds tested have been pindolol and, for comparison purposes, indole and 4-methoxyindole. The retention behaviour has been analysed on a Kromasil 100 C18 column and the mobile phase used was methanol-pH 6 phosphate buffer (15/85v/v) in which beta-CD was incorporated as a mobile phase additive. The decrease in the retention times with increasing concentrations of beta-CD enables the determination of the apparent stability constants of the complexes. In addition, the low solubility of pindolol, a weak base, in pH 12 aqueous solution has been improved by complexation with different cyclodextrins. The solubility enhancements with 1.4 x 10(-2) M beta-, hydroxypropyl-beta, and gamma-CD have been 1.9, 1.8 and 1.4-fold, respectively, with 2.4 x 10(-2) M methyl-beta-CD it was 2.8-fold whilst no effect was observed with alpha-CD. The stability constants of the complexes at pH 12 have been determined from the solubility isotherms.
Gazpio
Carmen
C
Departamento de Química y Edafología, Facultad de Ciencias, Universidad de Navarra, Irunlarrea s/n, Pamplona 31080, Spain.
Sánchez
Miguel
M
García-Zubiri
Iñigo X
IX
Vélaz
Itziar
I
Martínez-Ohárriz
Cristina
C
Martín
Carmen
C
Zornoza
Arantza
A
D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003505:Cyclodextrins / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism*; D004347:Drug Interactions; D010869:Pindolol / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism*; D012995:Solubility
D003505:Cyclodextrins; D010869:Pindolol