Bioadhesion and oral absorption of enoxaparin nanocomplexes.

Polyelectrolyte complexes (PEC) formed between chitosan derivatives and enoxaparin were prepared by a self-assembly process and were characterized in terms of particle size and surface charge. The morphology was observed by atomic force microscopy (AFM). The colloidal stability and bioadhesion of the PEC were characterized by dynamic light scattering (DLS). The absorption of enoxaparin in rats was evaluated by activated partial thromboplastin time (APTT) assay. It was shown that the prepared PEC had a spherical shape with positive charge and a mean diameter in the range of 200-600 nm. An increase in temperature led to a decrease in particle size (ca. 10%) with an increased kcps value (ca. 10-20%) for the PEC studied, depending on the polymer structure. Thiolation and methylation of chitosan could significantly improve the corresponding PEC's bioadhesion and hence the oral absorption of enoxaparin. A good relationship between bioadhesion and in vivo absorption was established. However, PEC of PEGylated chitosan did not display a significantly enhanced permeation of enoxaparin compared with unmodified chitosan. In conclusion, the oral bioavailability of enoxaparin can be enhanced by improving the bioadhesive properties of PEC via the chemical modification of chitosan employed.

Sun W ，Mao S ，Wang Y ，Junyaprasert VB ，Zhang T ，Na L ，Wang J ... -  《-》

Self-assembled polyelectrolyte nanocomplexes between chitosan derivatives and enoxaparin.

Sun W ，Mao S ，Mei D ，Kissel T ... -  《EUROPEAN JOURNAL OF PHARMACEUTICS AND BIOPHARMACEUTICS》

Exploration of hydrophobic modification degree of chitosan-based nanocomplexes on the oral delivery of enoxaparin.

The objective of this paper is to elucidate the influence of lipophilic modification degree of chitosan on the peroral absorption of enoxaparin. A series of novel chitosan grafted glyceryl monostearate (GM) copolymers with different GM substitution degree were synthesized and the successful synthesis was confirmed by (1)H NMR, FTIR and X-ray diffraction. Enoxaparin loaded nanocomplexes with different carriers were prepared by self-assembly process. Influence of GM substitution degree and chitosan molecular weight in the copolymer on the properties of the nanocomplexes was investigated. Morphology of the nanocomplexes was observed by atomic force microscopy. Mucoadhesive properties of the nanocomplexes were characterized using mucin particle method. Initially, mucoadhesion of the nanocomplexes increased with the increase of GM substitution degree and it started to decrease when the substitution degree was up to 18.6%. A good linear relationship between GM substitution degree and in vivo absorption of enoxaparin in fasted rats was established in the substitution degree range of 0-11.1%. In agreement with mucoadhesion data, further increasing GM substitution degree to 18.6% caused a decrease in oral absorption. In conclusion, oral bioavailability of enoxaparin can be enhanced by structure modification of the carriers and the bioavailability is hydrophobic modification degree dependent.

Wang L ，Li L ，Sun Y ，Tian Y ，Li Y ，Li C ，Junyaprasert VB ，Mao S ... -  《-》

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

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.

Bagre AP ，Jain K ，Jain NK 《-》

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

The aim of present study was to investigate the potential of mucoadhesive polymer chitosan (CS) and N-trimethyl chitosan (TMC) based nanoparticulate systems for oral bioavailability enhancement of low molecular weight heparin (LMWH). The TMC was synthesized by methylation of chitosan followed by characterization using infrared spectroscopy and (1)H-NMR spectroscopy. The IR and NMR spectra of TMC confirmed the presence of trimethyl groups and estimated the degree of quaternization for TMC about 46%. TMC nanoparticles were then prepared by ionic gelation method. The developed CS-NPs and TMC-NPs were characterized for various parameters including morphology, particle size, zeta potential, entrapment efficiency, in vitro release behavior and storage stability at different temperature and simulated gastrointestinal tract conditions. The fluorescent microscopy study confirmed the higher particle uptake of TMC-NPs by gastrointestinal epithelium in comparison to the CS-NPs. The concentration of LMWH in the systemic circulation followed by oral administration of formulations was estimated using FXa chromogenic assay. A significant increase (p<0.05) in the oral bioavailability of LMWH was observed with TMC-NPs than both CS-NPs as well as plain LMWH solution. These findings suggested that TMC nanoparicles hold promise for oral delivery of LMWH and clinical applicability for the treatment of vascular disorders like deep vein thrombosis and pulmonary embolism, etc.

Paliwal R ，Paliwal SR ，Agrawal GP ，Vyas SP ... -  《-》