Antibiotic-Cyclodextrin Interactions: An Effective Strategy for the Encapsulation of Environmental Contaminants

Area of Science:

• Physical Chemistry
• Solution Chemistry
• Supramolecular Chemistry

Background:

• Understanding drug-excipient interactions is crucial for pharmaceutical formulation.
• Cyclodextrins are widely used as pharmaceutical excipients due to their ability to form inclusion complexes.
• Antibiotics such as sulfamethoxazole (SMX) and trimethoprim (TMP) are common therapeutic agents.

Purpose of the Study:

• To investigate the interactions between SMX or TMP and various cyclodextrins (α-CD, β-CD, γ-CD) in aqueous solutions.
• To quantify these interactions using thermodynamic and transport properties.
• To elucidate the nature of host-guest complex formation.

Main Methods:

• Measurements of solution density and viscosity at 298.15 K.
• Determination of ternary mutual diffusion coefficients (D11, D12, D21, D22).
• Analysis of viscosity data using the Jones-Dole equation and calculation of viscosity B coefficients.
• Derivation of apparent molar volumes and partial molar volumes of transfer at infinite dilution.

Main Results:

• Positive viscosity B coefficients indicate structure-making effects of SMX and TMP in water.
• Negative partial molar volumes of transfer (ΔVφ0) suggest strong solute-solvent interactions.
• Negative cross-diffusion coefficients (D12 and D21) demonstrate significant coupled diffusion between antibiotics and cyclodextrins.
• Observed trends are consistent with the formation of antibiotic-cyclodextrin inclusion complexes.

Conclusions:

• Strong interactions exist between SMX/TMP and cyclodextrins in aqueous media.
• These interactions are indicative of host-guest complex formation.
• The findings provide valuable insights into the behavior of these drug-excipient systems.