Determination of the binding constant of indomethacin-ß-cyclodextrin complex by capillary electrophoresis: experimental optimization and temperature study

ACOSTA, GIMENA; LINARES, DANIEL; OLSINA, ROBERTO; MARTINEZ, LUIS DANTE; GOMEZ, MARÍA ROXANA

PHARMAZIE

Govi Verlag

Año: 2007 vol. 62 p. 847 - 852

0031-7144

The apparent electrophoretic mobilities of indomethacin in a series of concentration of b-cyclodextrin were measured directly by capillary electrophoresis technology. For the apparent binding constant calculations three different linear plots and a non liner plot are proposed, which are based on the fact that the molar ratio of the inclusion complex was 1:1. Obtained K values at 298 ºK were 421 M-1 (double reciprocal fit), 488 M-1 (x-reciprocal fit), 428 M-1 (y-reciprocal fit) and 490 M-1 (non linear fit). The corresponding K values at 313 ºK were 380 M-1 (double reciprocal fit), 355 M-1 (x-reciprocal fit), 366 M-1 (y-reciprocal fit) and 339 M-1 (non linear fit). Using the proposed method, the binding constant of the inclusion complex of indomethacin with b-cyclodextrin can be obtained easily. The methods have been applied to obtain the values of the constant K in different experimental conditions. At the optimized conditions the temperature dependence of the K constant is obtained and non-arrhenian behaviour is observed.