Loading of 5-aminosalicylic in solid lipid microparticles (SLM)

Solubility screening of lipid excipients and physicochemical characterization

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5-Aminosalicylic acid (5-ASA), the active moiety of sulphasalazine, is the most commonly used drug for treating patients with inflammatory bowel disease (IBD). Its bioavailability is low, i.e. 20–30% upon oral administration and 10–35% by rectal administration. As the extent of 5-ASA absorption is very much dependent on the time-length, the drug is retained in the colon, a way to increase drug retention is the use of orally administered sustained released formulations. Solid lipid microparticles (SLM) are a viable option for site-specific targeted delivery in compressed tablets produced by direct compaction. In this study, we describe the development and characterization of 5-ASA-loaded SLM for sustained release. The solubility of 5-ASA in different types of solid lipids (e.g. cetyl palmitate, cetyl alcohol, and cetearyl alcohol) was evaluated to select the best lipid as the inert matrix-forming agent to control the release of the drug. SLM dispersions were prepared using the hot emulsification method employing the selected solid lipid, lecithin (Lipoid®) as surfactant, dimethyl sulphoxide, and acetone stabilized with Arlacel®. The characterization was performed by differential scanning calorimetry, thermogravimetric analysis, wide-angle x-ray diffraction, Fourier transform infrared spectroscopy measurements, optical microscopy, and scanning electron microscopy. Results show that the best lipid for dissolving the 5-ASA was cetyl palmitate and that the melting process did not affect the chemical stability of the materials. The thermal analysis suggests that 5-ASA was successfully encapsulated with the microparticles, of spherical shape and uniform size distribution.

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The authors wish to thank Conselho Nacional de Desenvolvimento Científico e Tecnológico –CNPq (Processes #443238/2014-6 and #470388/2014-5) for their financial support. This work was also financed through the project M-ERA-NET/0004/2015 from the Portuguese Science and Technology Foundation, Ministry of Science and Education (FCT/MEC) from national funds, and co-financed by FEDER, under the Partnership Agreement PT2020.

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Correspondence to Eliana B. Souto or Patrícia Severino.

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Silveira, E.F., Rannier, L., Nalone, L. et al. Loading of 5-aminosalicylic in solid lipid microparticles (SLM). J Therm Anal Calorim 139, 1151–1159 (2020) doi:10.1007/s10973-019-08544-7

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  • Solid lipid microparticles
  • Cetyl palmitate
  • 5-aminosalicylic acid
  • DSC
  • WAXS
  • FTIR