Development and evaluation of sustained-release clonidine-loaded PLGA microparticles

Amélie Gaignaux*, Jonathan Réeff, Florence Siepmann, Juergen Siepmann, Carine De Vriese, Jonathan Goole, Karim Amighi

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

60 Citations (Scopus)


This work describes the encapsulation of a small, hydrophilic molecule (clonidine) into a PLGA matrix to provide sustained release over more than one month after intra-articular administration. The microparticles were prepared using a double emulsion (w1/o/w2) method followed by evaporation of the organic solvent. To optimize the efficiency of encapsulation and the mean size of the microparticles, which was targeted around 30 μm, the following parameters were modulated: the viscosity and the volume of the organic phase, the molecular weight of the polymer, the volume of the internal and external aqueous phases, the drug loading, the concentration of surfactant, and the stirring parameters. Blends of polymers characterized by different molecular weights (34 000-96 000 Da) as well as copolymers of PLGA-PEG were used to enhance the entrapment of the drug. The pH of the aqueous phases was adjusted to obtain suitable encapsulation efficiency. Characterization was made of the physico-chemical properties of the microparticles, such as their crystallinity (DSC and PXRD) and microstructure (SEM). When performing in vitro dissolution studies, controlled release for up to approximately 30 days was achieved with several of the formulations developed. Diffusion was found to be the dominant drug release mechanism at early time points.

Original languageEnglish
Pages (from-to)20-28
Number of pages9
JournalInternational Journal of Pharmaceutics
Issue number1-2
Publication statusPublished - 1 Nov 2012
Externally publishedYes


  • Clonidine
  • Controlled release
  • Double emulsion
  • Encapsulation efficiency
  • Microparticles
  • Poly(d,l-lactide-co-glycolide acid) (PLGA)


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