Evaluation of dissolution rates of physical mixtures of rutin with β-cyclodextrin

Rutin have been reported to exert numerous biochemical and pharmacological activities. Oral administration of rutin has been limited by its poor water solubility. Cyclodextrins have been recognized as potential candidates to overcome the poor solubility of rutin. Formulation with a physical mixture rather than a complex was desirable from a manufacturing viewpoint [1,2].

The aim of this study was to compare the dissolution profiles of rutin, alone or in the combination with β-cyclodextrin (β-CD).

The samples used for the dissolution study were rutin alone or in the combination with β-cyclodextrin (rutin: β-CD molar ratio: 1:20, 1:4, 1:2, 1:1.5, 1:1). The inclusion complexes of rutin with β-cyclodextrin were prepared by direct mixing in dissolution vessel (in-situ complexation). Fixed volumes of the dissolution medium were withdrawn at 0.5, 1, 4, 8 and 14 hours. Dissolution tests were performed on the USP Apparatus 2 (Dissolution tester ERWEKA DT 800; rotating speed 100 rpm at 37±0.5^°C, 500 mL distilled water). Quantification of rutin in solutions was performed by UV/VIS spectrophotometric method at the absorption maximum around 258nm.

The dissolved amount of both alone or complexed rutin rapidly increases within 1h, folloved by a slower dissolution until it reaches a plateau after about 4h. The dissolved amounts of rutin in combination with β-cyclodextrin at the end of testing were increased in range of 11.48 to 58.69%

The in-situ complexation of rutin with β-cyclodextrin in all cases led to an increased dissolution rate and can be used to modify release rates of rutin in controlled-release devices.

References: [1] Calabro, M. L. et al. (2005)J. Pharmaceut. Biomed. 36:1019–1027.

[2] Carrier, R.L. et al. (2007)J. Control. Release 123:78–99.