Characterization of drug interactions with soluble beta-cyclodextrin by high-performance affinity chromatography

Area of Science:

• Analytical Chemistry
• Biochemistry
• Pharmacology

Background:

• Understanding drug-cyclodextrin interactions is crucial for drug formulation and delivery.
• Human serum albumin (HSA) and beta-cyclodextrin (beta-CD) are common molecules in pharmaceutical research.
• Chromatographic methods offer sensitive detection of molecular interactions.

Purpose of the Study:

• To develop and validate a chromatographic method for quantifying solution-phase binding between drugs and beta-cyclodextrin.
• To determine the stability constants of drug-beta-CD complexes using an immobilized HSA column.
• To assess the applicability of the method to various drug molecules.

Main Methods:

• Utilized an immobilized human serum albumin (HSA) column in conjunction with varying concentrations of beta-cyclodextrin (beta-CD) in the mobile phase.
• Employed chromatographic equations to characterize binding interactions between injected drugs (warfarin, tamoxifen, phenytoin) and beta-CD.
• Measured changes in drug retention factors to calculate stability constants.

Main Results:

• Successfully determined 1:1 interaction stability constants for warfarin-beta-CD (5.2 x 10(2) M⁻¹), tamoxifen-beta-CD (0.9-1.2 x 10⁴ M⁻¹), and phenytoin-beta-CD (6-9 x 10² M⁻¹).
• Results for warfarin-beta-CD closely matched existing literature values.
• Identified the need to account for secondary binding effects for tamoxifen and phenytoin.

Conclusions:

• The developed chromatographic method is effective for determining drug-beta-cyclodextrin stability constants.
• The approach is adaptable for analyzing interactions between various analytes and soluble ligands.
• This technique provides valuable insights into drug-excipient interactions relevant to pharmaceutical development.