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Diclofenac-beta-cyclodextrin binary systems: physicochemical characterization and in vitro dissolution and diffusion
Maria Letizia Manca1, Marco Zaru, Guido Ennas
1Dipartimento Farmaco Chimico Tecnologico, Università di Cagliari, Via Ospedale 72, 09124 Cagliari, Italy.
AAPS Pharmscitech
|December 16, 2005
Summary
Beta-cyclodextrin (beta-CD) forms a 1:1 inclusion complex with diclofenac (DCF), enhancing its dissolution rate. Freeze-dried binary systems show improved drug release, though diffusion is more regular with the complex.
Area of Science:
- Pharmaceutical Sciences
- Physical Chemistry
- Materials Science
Background:
- Diclofenac (DCF) is a widely used non-steroidal anti-inflammatory drug (NSAID).
- Beta-cyclodextrin (beta-CD) is a cyclic oligosaccharide known for its ability to form inclusion complexes with various molecules.
- Improving the biopharmaceutic properties of drugs like DCF is crucial for enhanced therapeutic efficacy.
Purpose of the Study:
- To investigate the influence of beta-cyclodextrin (beta-CD) on the biopharmaceutic properties of diclofenac (DCF).
- To characterize the physicochemical properties of DCF-beta-CD binary systems in solid state and solution.
- To evaluate the impact of preparation methods and molar ratios on complex formation and drug release.
Main Methods:
- Physicochemical characterization using differential scanning calorimetry (DSC), powder X-ray diffractometry (XRD), and Fourier transform infrared spectroscopy (FTIR).
- Phase solubility studies and in vitro permeation experiments through a synthetic membrane.
- 1H nuclear magnetic resonance (NMR) spectroscopy in DMSO to study drug-CD interactions.
Main Results:
- Phase solubility studies indicated a 1:1 molar complexation of DCF with beta-CD, particularly when using the freeze-drying method.
- Solid-state analyses (NMR, DSC, XRD, FTIR) confirmed the formation of true inclusion complexes in the freeze-dried binary system.
- Dissolution studies showed an improved drug dissolution rate with beta-CD, with the freeze-dried system exhibiting the highest and promptest release.
- Diffusion experiments revealed higher DCF diffusion from the control solution compared to freeze-dried inclusion complexes, but the complex stabilized the diffusion profile.
Conclusions:
- Beta-cyclodextrin effectively forms inclusion complexes with diclofenac, significantly enhancing its dissolution rate.
- The freeze-drying method is optimal for preparing stable DCF-beta-CD inclusion complexes with superior drug release characteristics.
- While complexation may alter diffusion rates, it provides a more regular and stable drug release profile.