Complexation and solubility behavior of albendazole with some cyclodextrins

Area of Science:

• Pharmaceutical Sciences
• Physical Chemistry

Background:

• Albendazole is an anthelmintic drug with poor aqueous solubility.
• Improving albendazole's solubility and dissolution is crucial for effective drug delivery and bioavailability.

Purpose of the Study:

• To investigate the complexation equilibrium between albendazole and various cyclodextrins.
• To identify an optimal cyclodextrin excipient for enhancing albendazole's solubility and dissolution rate.
• To elucidate the binding interactions and structural aspects of albendazole-cyclodextrin complexes.

Main Methods:

• Complexation equilibrium studied using electronic absorption spectroscopy and molecular mechanics.
• Phase solubility studies and direct spectroscopy employed to determine binding constants and complex stoichiometry.
• Dissolution rate studies conducted at pH 7.5 to assess the impact of cyclodextrins on drug release.

Main Results:

• Hydroxypropylated beta-cyclodextrin (HP-beta-CD) exhibited the highest binding constant with albendazole.
• Both un-ionized and ionized albendazole species interacted with HP-beta-CD.
• A 1:1 inclusion complex was identified for all studied cyclodextrins.
• Dissolution rates increased with cyclodextrin concentration, particularly for beta-CD and HP-beta-CD.
• Hydrophobic effect was identified as the primary driving force for complexation.

Conclusions:

• HP-beta-CD is a promising excipient for improving albendazole solubility and dissolution.
• The 1:1 inclusion complex formation facilitates enhanced drug release.
• Understanding the complexation mechanism aids in the rational design of albendazole formulations.