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| Author(s): |
Lucas Bessa Prado
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Faculdade de Ciências Médicas |
| Defense date: | 2013-01-30 |
| Examining board members: |
Joyce Maria Annichino Bizzacchi;
Erich Vinicius De Paula;
Maria Palmira Daflon Gremião
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| Advisor: | Joyce Maria Annichino Bizzacchi |
| Abstract | |
Deep vein thrombosis (DVT) is defined as partial or total occlusion of the deep venous circulation. Heparin is a drug with anticoagulant and antithrombotic action used since 1930. The costs, administration vias (intravenous or subcutaneous) and the repeated doses are some limitations of its use. Thus, the development of a product that could be administered subcutaneous or orally in a smaller number of applications becomes a major challenge with huge clinical applicability. Sustained release systems allow the medication to be gradually encapsulated and released. This study was based on the preparation, characterization and in vivo evaluation of nanoparticles of poly (?-caprolactone) (PCL) and chitosan as carriers of low molecular weight heparin (enoxaparin). The nanoparticles were prepared by the double emulsion water/oil/water method and solvent evaporation. The nanoparticles characterization was performed by scanning electron microscopy (SEM), in which were observed spherical and homogeneous particles. The average diameter of the nanoparticles was 512.8 ± 13.8 nm and the zeta potential was +30.9 ± 1.3 mV. The encapsulation efficiency, analyzed by Azure II method, was 99.04 ± 0.001%. The in vivo anticoagulant activity of the encapsulated enoxaparin was evaluated by plasmatic anti-Xa activity performed by colorimetric method. When the free enoxaparin was subcutaneously administered a peak of activity was observed (0.5 IU/mL) in 1 hour with a gradual decrease until 6 hours. The anticoagulant activity of the nanoparticles encapsulated enoxaparin was kept until 14 hours when it was administered subcutaneously, suggesting that nanoparticles may allow the enoxaparin release by a gradual way, what could be an advantage on clinical practice. After the oral administration of the nanoparticles, any activity could be observed in until 14 hours, suggesting that or the nanoparticles might be not absorbed or the enoxaparin might be degraded on the gastrointestinal tract. In order to evaluate its antithrombotic effect, it was standardized a model of DVT by stasis and hypercoagulability in rats. After subcutaneous administration, there was a significative reduction on the thrombus size both with free enoxaparin (p= 0.002) and after encapsulation (p= 0.0411) in comparison with control group. When nanoparticles were administered orally, the results showed no statistical difference compared to the control group (p = 0.9476) and to a group of empty nanoparticles (p = 0.9372). In summary, the double emulsion method w/o/w was efficient for the enoxaparin encapsulation, providing the obtainment of spherical nanoparticles with high encapsulation efficiency. For in vivo studies, the encapsulated enoxaparin showed a sustained release anticoagulant activity for a higher period than that obtained with free enoxaparin, with an excellent antithrombotic effect when administered subcutaneously. However, there was no anticoagulant or antithrombotic effect when the nanoparticles were administered orally. Further experiments with chitosans of different molecular weights will be needed on the attempt to allow the oral absorption of these nanoparticles (AU) | |
| FAPESP's process: | 10/04395-1 - EVALUATION OF THE ANTICOAGULATING AND ANTITHROMBOTIC ACTIVITY OF NANOPARTICLES WITH HEPARIN IN NICE MODEL OF DEEP VENOUS THROMBOSIS. |
| Grantee: | Lucas Bessa Prado |
| Support Opportunities: | Scholarships in Brazil - Master |