Colchicine encapsulation within poly(ethylene glycol)-coated poly(lactic acid)/poly(ε-caprolactone) microspheres-controlled release studies

G. S. Das, G. H.R. Rao, R. F. Wilson, T. Chandy

Research output: Contribution to journalArticle

32 Scopus citations

Abstract

Smooth muscle cell proliferation plays a major role in the genesis of restenosis after angioplasty or vascular injury. Local delivery of agents capable of modulating vascular responses have the potential to prevent restenosis. However, the development of injectable microspheres for maintaining high tissue levels of drugs at the site of vascular injury is a major challenge. We demonstrated the possibility of entrapping an antiproliferative agent, colchicine, in polyethylene glycol (PEG)-coated biodegradable microspheres composed of poly(lactic acid)/poly(ε-caprolactone) blends, with a mean diameter of 3-6 μm. A solution of colchicine and blends of polylactic acid (PLA)/polycaprolactone (PCL) dissolved in acetone-dichloromethane mixture was poured into an aqueous solution of PEG (or polyvinyl alcohol) with stirring by a high-speed homogenizer to form microspheres. Colchicine recovery in microspheres ranged from 30-50% depending on the emulsification system and the ratio of polymer blends used for the preparations. Scanning electron microscopy revealed that the PLA/PCL microspheres were spherical in shape and had a smooth surface texture. Results of in vitro release studies showed that it is possible to control the colchicine release by choosing the appropriate particle size, loading, and PLA/PCL composition. Water permeability through the PLA membrane was greater, when compared with PCL blends. The amount of drug release also was much higher (58.3%) in PLA compared with PCL (39.3%) microspheres, for 30 days. Therefore, we concluded that the drug release from the microspheres followed a diffusion mechanism where bulk erosion and surface deposition were negligible. These PEG-coated PLA/PCL microspheres may have potential for targeting antiproliferative agents for prolonged periods to treat restenosis.

Original languageEnglish (US)
Pages (from-to)129-138
Number of pages10
JournalDrug Delivery: Journal of Delivery and Targeting of Therapeutic Agents
Volume7
Issue number3
StatePublished - Sep 30 2000

Keywords

  • Colchicine Encapsulation
  • Controlled Release
  • Microspheres
  • Poly (Ethylene Glycol)
  • Poly (Lactic Acid)
  • Poly(ε-Caprolactone)

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