SbstractOxaliplatin was inserted into polymeric matrices aiming to study the interaction of this drug with these polymers and its capability to diffuse to the environment. Tested polymers were: (1) polyethylene glycol (PEG), (2) poly(lactic-co-glycolic acid) (PLGA), and (3) a copolymer of them (PLGA-PEG). The latter two were synthesized by us using polycondensation in bulk. Oxaliplatin was included in the matrices by the melt mixing process followed by casting. Fourier tran sform infrared spectroscopy (FTIR), proton nuclear magnetic resonance ( 1 H-NMR) and X-ray diffraction (DRX) studies of the polymers were performed proving the obtaining of the desired materials. In addition, the interaction between drug and matrices and the release profile of the oxaliplatin from these matrices were analyzed. Among them, PEG did not control the oxaliplatin release. In turn, PLGA and PLGA-PEG present drug release profiles quite similar. Oxaliplatin was completely released from PLGA and PLGA-PEG in 5 hours, by a relaxation mechanism. There was no evidence of oxaliplatin interaction with the different polymers. In addition, as the PEG improves the biocompatibility and biomasking, obtained results prove the obtaining of a drug release system, which allowed the total use of the drug improving the cancer treatment and even the welfare of the patients.
Summary: The antibiotic cotrimoxazole was associated to the multi-block copolymer containing poly(D,L-lactic-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG) segments, PLGA-PEG-PLGA, aiming to reach a controlled drug release system. Block copolymer was synthesized via polycondensation of lactic acid and glycolic acid with PEG in situ. In turn, maghemite was synthesized through the co-precipitation method. The drug cotrimoxazole was inserted in the composite through melting mixing method. Several techniques were used to characterize the materials. The materials were characterized by Nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and magnetic force, this last according to the methodology developed by our group. In addition, dissolution profile was studied. These dissolution tests were performed with and without magnetic field, aiming to study the influence of the magnetic field on the dissolution profile. The dissolution was monitored and quantified using the ultraviolet-visible spectrophotometry (UV-Vis), following the USP method for cotrimoxazole tablets. Results demonstrated that nanocomposites presented a good magnetic force, able to keep the magnetic composite trapped in a specific place or tissue. Furthermore, in the presence of a magnetic field, the magnetic nanoparticles were able to perform a magnetic constriction of the material, making the drug release faster than in the absence of the magnetic field. This phenomenon may be useful to perform a fine tuning of the system, allowing the easier adjust of the speed and amount of released drug, useful to improve medical treatments and even the welfare of the patients.
Summary Oxaliplatin (OP) is an anti‐tumor agent used for advanced colorectal cancer treatment. Therapies with OP produce side effects, which could be reduced by its encapsulation into PLGA microspheres (MS). The determination of OP content in MS is important for defining the exact quantity of loaded particles into final formulation and achieve correct dosage of this drug. This research focuses on determining OP through the Pt residue which is quantified by thermogravimetric analysis (TGA). It was demonstrated that there is no significant difference between the intrinsic residues for MS obtained with the PLA or PLGA. In turn, a statistically significant difference was detected between residue of tested polymers. The linearity was proved (R2 = 0.9998) by evaluating samples prepared from mixtures of empty PLGA MS and known quantities of OP. The detection limit was equal to 0.25% Pt residue while the quantitation limit was equal to 0.78%. Thus, TGA allows to quantify oxaliplatin loadings as small as 1.57 wt% in samples of 20 mg.
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