Pharmaceutical nanotechnology
Alginate coated chitosan core shell nanoparticles for oral delivery of enoxaparin: In vitro and in vivo assessment

https://doi.org/10.1016/j.ijpharm.2013.08.037Get rights and content

Abstract

The objective of present research work was to develop alginate coated chitosan core shell nanoparticles (Alg-CS-NPs) for oral delivery of low molecular weight heparin, enoxaparin. Chitosan nanoparticles (CS-NPs) were synthesized by ionic gelation of chitosan using sodium tripolyphosphate. Core shell nanoparticles were prepared by coating CS-NPs with alginate solution under mild agitation. The Alg-CS-NPs were characterized for surface morphology, surface coating, particle size, polydispersity index, zeta potential, drug loading and entrapment efficiency using SEM, Zeta-sizer, FTIR and DSC techniques. Alginate coating increased the size of optimized chitosan nanoparticles from around 213 nm to about 335 nm as measured by dynamic light scattering in zeta sizer and further confirmed by SEM analysis. The performance of optimized enoxaparin loaded Alg-CS-NPs was evaluated by in vitro drug release studies, in vitro permeation study across intestinal epithelium, in vivo venous thrombosis model, particulate uptake by intestinal epithelium using fluorescence microscopy and pharmacokinetic studies in rats. Coating of alginate over the CS-NPs improved the release profile of enoxaparin from the nanoparticles for successful oral delivery. In vitro permeation studies elucidated that more than 75% enoxaparin permeated across the intestinal epithelium with Alg-CS-NPs. The Alg-CS-NPs significantly increased (p < 0.05) the oral bioavailability of enoxaparin in comparison to plain enoxaparin solution as revealed by threefold increase in AUC of plasma drug concentration time curve and around 60% reduction in thrombus formation in rat venous thrombosis model. The core shell Alg-CS-NPs showed promising potential for oral delivery and significantly enhanced the in vivo oral absorption of enoxaparin.

Introduction

Low molecular weight heparin (LMWH) is glycosaminoglycan, which is used as anticoagulant agent in the treatment of vascular disorders like venous thromboembolism, deep vein thrombosis and pulmonary embolism. Apart from anticoagulant activity, LMWH has been also found applicable in inhibition of progression of cancer as well as in therapy of rheumatoid arthritis attributed to antiangiogenic activity of LMWH. The advantages of LMWH over heparin are that it does not cause severe toxicities, for example thrombocytopenia and bleeding (Hwang et al., 2012, Khatun et al., 2012, Jain et al., 2013). The clinical applicability of this low molecular weight heparin therapy is limited by the fact that it is given only by parenteral route due to its high molecular size as well as high negative charge, poor permeation through intestinal wall and high water solubility. In order to improve patient compliance oral heparin therapy is needed for long time. Various approaches including penetration enhancers (Hayes et al., 2006), microparticles (Javot et al., 2009), polymeric nanoparticles (Chen et al., 2009) dendrimeric nanocarriers (Bai and Ahsan, 2009), chemical conjugates (Lee et al., 2006), etc. have been investigated for oral delivery of heparin. At present no oral formulation of heparin is available in the market (Kim et al., 2011, Hwang et al., 2012).

Oral formulation offers economical and effective solution to limitations of parenteral administration in addition to improved patient compliance and non-invasive administration (Shah et al., 2005, Oliveira et al., 2012, Paliwal et al., 2012). Chitosan is a biodegradable, biocompatible, mucoadhesive cationic polymer, which can easily form complexes or nanoparticles in aqueous medium with the ability to encapsulate drug molecules. Nanoparticles prepared from chitosan and chitosan derivatives have shown promising potential in oral delivery of bioactives including LMWH owing to their biocompatibility, low toxicity and high loading potential (Wan et al., 2011, Oliveira et al., 2012, Trapani et al., 2013). Oral delivery potential of chitosan is limited by its solubility at acidic pH, which causes dissolution of chitosan at gastric pH condition, leading to loss of mucoadhesive and permeability enhancing properties of chitosan (Li et al., 2008, Paliwal et al., 2012). Sodium alginate has been exploited for sustained, controlled and oral delivery of bioactives without risk of mucosal damage (Kanjanabat and Pongjanyakul, 2011, Rajesh et al., 2012). Sodium alginate coating may be applied to chitosan nanoparticles to protect encapsulated drug from enzymes and acidic environment of gastrointestinal (GI) tract due to acid-resistant property of alginate. Alginate coating may further modify the release behavior of bioactive from chitosan nanoparticles instigating more efficient oral delivery aptitude. The alginate coated chitosan nanoparticles are also easy to prepare under mild conditions like aqueous medium and mild agitation. The alginate–chitosan based nanoparticulate systems have been studied for delivery of various bioactives like hepatitis B surface antigen (Borges et al., 2008), turmeric oil (Lertsutthiwong et al., 2009) and gene transfection (You et al., 2006), etc. Oral delivery with chitosan nanoparticles coated with sodium alginate is expected to provide advantages of improved stability, controlled drug delivery, high drug payload as well as protection from acidic and proteolytic environment of GI tract (Li et al., 2008, Kanjanabat and Pongjanyakul, 2011, Oliveira et al., 2012).

In this study we proposed to evaluate alginate coated chitosan nanoparticles loaded with low molecular weight heparin, enoxaparin, for oral delivery as well as for controlled and prolonged release of enoxaparin for with improved patient compliance.

Section snippets

Materials

Chitosan (molecular weight 150 kDa, degree of deacetylation 85%, purified viscosity grade 80 cps) was received as a benevolent gift from Central Institute of Fisheries Technology (Cochin, India). LMWH, Enoxaparin sodium (mean MW 4.5 kDa) was purchased from Emcure pharmaceuticals (Pune, India). Sodium alginate (medium viscosity grade ∼50 kD) and dialysis membrane (MWCO 12–14 kDa) were purchased from Himedia Labs, Mumbai, India. Sodium tripolyphosphate (STPP) was purchased from Sigma (Germany). Other

Preparation of core shell nanoparticles

The chitosan nanoparticles were prepared by ionic gelation technique using different chitosan: STPP ratio and optimized on the basis of particle size and drug entrapment efficiency (Table 1). The size of nanoparticles was found to increase from 177 ± 4.2 to 289 ± 5.4 nm on increasing the ratio of polymer from 2 to 6 with respect of STPP. This increase in size was possibly attributed to increased collision of the chitosan polymer with TPP ions. Chitosan: STPP ratio 5:1 was considered optimum because

Discussion

Oral delivery of therapeutic heparins is foremost requirement for non-invasive and non-hospitalized treatment of vascular disorders (deep vein thrombosis, pulmonary embolism and venous thromboembolism). This urge necessitated the development of a macromolecular carrier system with optimum hydrophilicity, high charge density to interact with intestinal epithelium and traverse across the intestinal barrier (Goldberg and Gomez-Orellana, 2003, Paliwal et al., 2011, Hwang et al., 2012). The

Conclusion

The strategy for the oral delivery of low molecular weight heparin is desperately needed. Chitosan nanoparticles presented excellent opportunity in this regard but it suffers with some problems including lower solubility of chitosan at neutral or at higher pH. So development of core shell nanoparticles by coating chitosan nanoparticles with alginate may overcome the limitations of plain chitosan nanoparticles. The study suggest that alginate coated chitosan core shell nanoparticles could be

Acknowledgement

Author Archana Pataskar is grateful to All India Council for Technical Education (AICTE), New Delhi, India for providing Junior Research Fellowship (JRF).

References (42)

  • S. Kim et al.

    A newly developed oral heparin derivative for deep vein thrombosis: non-human primate study

    J. Control. Release

    (2007)
  • Y.K. Lee et al.

    Efficacy of orally active chemical conjugate of low molecular weight heparin and deoxycholic acid in rats, mice and monkeys

    J. Control. Release

    (2006)
  • P. Lertsutthiwong et al.

    Preparation of turmeric oil-loaded chitosan–alginate biopolymeric nanocapsules

    Mater. Sci. Eng. C

    (2009)
  • R. Paliwal et al.

    Chitosan nanoconstructs for improved oral delivery of low molecular weight heparin: in vitro and in vivo evaluation

    Int. J. Pharm.

    (2012)
  • L. Peternel et al.

    Evaluation of two experimental venous thrombosis models in the rat

    Thromb. Res.

    (2005)
  • R.J. Schilling et al.

    Intestinal mucosal transport of insulin

    Int. J. Pharm.

    (1990)
  • W. Sun et al.

    Bioadhesion and oral absorption of enoxaparin nanocomplexes

    Int. J. Pharm.

    (2010)
  • M.M. Thanou et al.

    Effect of degree of quaternization of N-trimethyl chitosan chloride for enhanced transport of hydrophilic compounds across intestinal caco-2 cell monolayers

    J. Control. Release

    (2000)
  • A. Trapani et al.

    Systemic heparin delivery by the pulmonary route using chitosan and glycol chitosan nanoparticles

    Int. J. Pharm.

    (2013)
  • V. Agarwal et al.

    Current status of the oral delivery of insulin

    Pharm. Technol.

    (2001)
  • R.S.T. Aydin et al.

    5-Fluorouracil encapsulated chitosan nanoparticles for pH-stimulated drug delivery: evaluation of controlled release kinetics

    J. Nanomater.

    (2012)
  • Cited by (0)

    View full text