Fluorescent probe study of sulfonamide binding to povidone

Area of Science:

• Pharmaceutical Sciences
• Physical Chemistry

Background:

• Povidone (I) is a widely used polymer in pharmaceutical formulations.
• Understanding drug-povidone interactions is crucial for drug delivery and stability.

Purpose of the Study:

• To investigate drug-povidone interactions using a fluorescent probe technique.
• To elucidate the binding mechanisms and affinities of different sulfonamides to povidone.

Main Methods:

• Utilized 1-anilino-8-naphthalenesulfonate (II) as a fluorescent probe.
• Employed competitive binding assays with sulfanilamide, sulfacetamide, and sulfabenzamide.
• Analyzed fluorescence intensity changes and applied double reciprocal plots and the Klotz equation.

Main Results:

• Sulfacetamide and sulfabenzamide decreased fluorescence intensity, indicating binding to povidone, with sulfabenzamide showing stronger binding.
• Sulfanilamide increased fluorescence intensity, suggesting an intermediary role possibly via hydrogen bonding.
• The povidone-probe (I-II) binding constant was 3.2 x 10^4 M^-1.
• Association constants for sulfacetamide and sulfabenzamide were 13.4 M^-1 and 56.8 M^-1, respectively.

Conclusions:

• Drug-povidone interactions are influenced by both hydrophobic and hydrogen bonding mechanisms.
• The fluorescent probe technique provides a valuable method for studying drug-excipient interactions.
• Povidone exhibits approximately 1.28 binding sites for the studied sulfonamides under experimental conditions.