Inclusion complex of trimethoprim with beta-cyclodextrin.

Area of Science:

• Pharmaceutical Chemistry
• Drug Delivery Systems
• Supramolecular Chemistry

Background:

• Trimethoprim (TMP) is an antibiotic with limited aqueous solubility, affecting its bioavailability.
• Beta-cyclodextrin (beta-CD) is a cyclic oligosaccharide known for its ability to form inclusion complexes with poorly soluble drugs.
• Complexation with beta-CD can improve the physicochemical and biopharmaceutical properties of drug molecules.

Purpose of the Study:

• To investigate the complexation of trimethoprim (TMP) with beta-cyclodextrin (beta-CD).
• To evaluate the impact of complexation on TMP's aqueous solubility and in vitro dissolution characteristics.
• To characterize the formation and properties of the TMP/beta-CD inclusion complex.

Main Methods:

• UV-spectrophotometry and phase-solubility studies were used to analyze complexation in aqueous solutions.
• Differential scanning calorimetry (DSC) and powder X-ray diffraction (XRD) were employed to characterize solid-state inclusion complex formation.
• Thermogravimetric analysis (TGA) was used to determine water content.
• In vitro dissolution tests were performed to compare the dissolution profiles of the complex, pure TMP, and a physical mixture.

Main Results:

• Complexation with beta-CD increased the aqueous solubility of TMP by 2.2-fold.
• Solid-state characterization confirmed the formation of the TMP/beta-CD inclusion complex.
• The TMP/beta-CD complex exhibited significantly superior in vitro dissolution properties compared to pure TMP and its physical mixture with beta-CD.

Conclusions:

• Beta-cyclodextrin effectively forms an inclusion complex with trimethoprim, enhancing its aqueous solubility.
• The TMP/beta-CD inclusion complex demonstrates improved dissolution characteristics, suggesting potential for enhanced drug delivery.
• This complexation strategy offers a promising approach to improve the pharmaceutical performance of trimethoprim.