Research On Metronidazole Benzoateloadedpoly (Lactic-co-glycolic Acid)Nanoparticles-Silicone Elastomer Pharmaceutical Preparation

Maxillaries need to be cutted down to get a thorough theraphy when they were damaged by different tumors, severe trauma or congenital factors in clinic. The defect maxillary caused by cutting will give patients facial deformities and even chew, swallow and speaking impediment. Therefore, the patients whose maxillary have been cutted should have a surgery to reconstruct the damage section then have a recovery on both physiology and psychology.Nowadays, prostheses restore is the common method applied in maxillary reconstruction. Prostheses restore have many superior properties in trauma, moulding, reviewing tumors in the involved section and restoring the chewing, swallowing, speaking functions nicely.Silicone elastomer is the first choice material in reconstructing the soft tissue defects of the oral and maxillofacial region due to the low toxicity and perfect mechanical properties. However, the traditional silicone elastomers are limited in dental clinic because high density and bacterial reproduction. The high density property will cause some difficulities in fixing during surgery or wearing. The patients need to have one more surgery to replace the prostheses and will suffer more pains in the therapy. Moreover, it is hard to polish the surface of silicone elastomer, and varieties of pathogenic microorganisms such as bacteria will aggregate on the verge and surface of silicone elastomer, worsely, the silicone elastomer will be degradated when microorganisms moved into the inner of the composites.Drug-loaded nanoparticles are drug reservoir devices which cover the solid or liquid drugs with natural or synthetic polymers materials with the particles size less than1μm. Currently, many materials are used for nanoparticles, including chitosan, polylactic acid, polyhydroxybutyrate, poly (lactic-co-glycolic acid, PLGA) et al.. PLGA are widely used for sustained pharmaceutical preparation with its good biocompability and degradation property. The metabolize production of PLGA in vivo are carbon dioxide and water which will not cause the inflammatory response, immune response or cell toxicity. At present, there are many PLGA nanoparticles preparation on market, such as, tetanus toxoid PLGA nanoparticles injection which is the first injection vaccine licensed by WHO, luteinizing hormone-releasing hormone analogue-Triptorelin which is the first polypeptide controlled-releasing injection preparation, leuproreling which is developed by Takeda Pharmaceutical Company Limited and so on.Some experts had studied the effect of hollow microspheres on silocone elastomer. The results indicated the density can be decreased significantly and the physical and mechanical properities can be partly improved. Therefore, we designed to fabricate the antibiotic-loaded microspheres which will be mixed into silocone elastomer to make the silocone elastomer with anti-bacteria activity and a good physical and mechanical properity.Fusobacterium nucleatum (F.n) is one of the bacterica which induce the common inflammatory response in dental clinic and it is an opportunistic anaerobes bacterica with gram-negative character will produce inflammation response following the local position changed when prostheses are implanted accompanied with the weak immunity of patient after surgery. Furthermore, F.n can promote bacterial biofilm formation and improve the pathogenicity while enhance the release of proinflammatory cytokine from mononuclear cell, enhance the activity of NF-κ-B and even induce the defect of alveolar bone followed the decreasing of density of alveolar bone, all those characters will have adverse effect on the prognosis of patients.Metronidazole benzoate (MEB) is a nitromidazoles antibiotic which is applied to anti-anaerobic infections in clinic. MEB has some superior properity such as tasteless, fat-soluble, and broad antibacterial spectrum properity. MEB has anti-bacteria activity on many bacteria such as, fusobacterium including F.n, fusobacterium necrophorum and clostridium microbial bacilli; bacteroides fragilis group including bacteroides fragilis, ji shi bacilli, bacteroides vulgatus and polymorphic class; eubacterium including eubacterium limosum and so on. MEB has already been recorded in British Pharmacopoeia, USA Pharmacopoeia and Japanese Pharmacopoeia to treat inflammatory disease caused by anaerobic. Meanwhile, there are many different preparations on sale in China, such as capsule, tablets and suspension.To overcome the above problems, we designed metronidazole benzoate loaded poly(lactic-co-glycolic acid) nanoparticles-silicone elastomer(MEB-PLGA-NPs-SE) pharmaceutical preparation. We hoped the pharmaceutical preparation can further sustain the release of MEB with good mechanical properties and can have anti-bacteria activity, so that the patients can have less opportunity to get dental inflammatory and improve the postoperative living quality. The main objective of the novel pharmaceutical preparation was to improve the characters of silicone elastomer in one aspect of the slow degradation of PLGA to control the release of MEB, and another aspect of the low density, large inner volume to decrease the density of silicone elastomer and the quantity of prostheses.Around those objectives, the research was carried out in this paper as followed.MEB-PLGA-NPs were prepared with single emulsion-solvent evaporation method due to the physical properity of MEB and PLGA. Firstly, we researched on the pre-prescription of MEB-PLGA-NPs, such as maximum absorption wavelength, HPLC detect method, drug-loading (DL), entrapment efficiency (EE) and freeze drying method. The DL was used as the main optimized indexes to compare the quality of MEB-PLGA-NPs with the influence factors of the quantity of MEB and PLGA, the concentration of PVA, mixing speed and the ratio of oil phase to water phase. The optimized prescription was obtained by orthogonal design on the factors of the quantity of MEB and PLGA, the concentration of PVA and the ratio of oil phase to water phase. The MEB-PLGA-NPs prepared under the optimisum prescription were white powder with good properities of redissolve and flowing. The mean drug-loading of MEB-PLGA-NPs were (3.59±0.15)%, the entrapment efficiency were (39.52±1.65)%, while the particle size were (312.03±12.77) nm. MEB has a controlled release character from MEB-PLGA-NPs. The cumulative release rate of MEB was29.03±2.66%at24h,49.70±4.08%at120h. The cumulative release reach maximum rate was55.60±5.01%at240h.Silicone elastomers were prepared with the impoved method involved references. Different weight/weitht (0%、0.2%、0.4%、0.8%、1.2%) MEB (and10%、20%、30%MEB-PLGA-NPs fabricated by our group) were added into silicone elastomer to get novel silicone elastomer pharmaceutical preparation. Silicone elastomer samples had smooth surface and no residual bubbles. The MEB (or MEB-PLGA-NPs) were dispersed uniformly and the number of particles increasing along the additives under scanning electron microscope. The MEB contained in all silicone elastomer pharmaceutical preparations compared to theory amount were97%-104%indicated there were no additives aggregation to affect the detected MEB. The vitro releases of silicone elastomer pharmaceutical preparations were carried out on1.2%MEB-SE samples and30%MEB-PLGA-NPs-SE samples. The30%MEB-PLGA-NPs-SE samples had further control MEB release than1.2%MEB-SE samples.The anti-bacteria activity on F.n ATCC10953was carried out with Kirby-Bauer method under the requirement of NCCLS. The results indicated the silicone elastomer pharmaceutical preparations had an anti-bacteria activity on F.n ATCC10953, the bacteriostatic rings were22.10±0.17mm in30%MEB-PLGA-NPs-SE and there was a significant difference in all groups. The cell toxicity test was carried out under ISO10993-12:2002. The cell toxicity of all experiment groups were all less than1level and reach the eligible requirement according to the standard.Prostheses will suffer the acting force coming from all directions after being implanted during the postoperative living specially in chewing, swallowing and speaking. It is importance to study the physical and mechanical properities for further study. Tensile strength and tensile elongation were carried out under ISO37:2005. The result indicated the tensile strength had a reduce trendency along the quantity of additives. There was a significant effect when MEB reached1.2%. However, there was no significant difference on tensile elongation. The tear strength was carried out under ISO34-1:2004. The result indicated tear strength had a reduce trendency along the quantity of additives. There was a significant effect when MEB-PLGA-NPs reached20%. The shore hardness was carried out under ISO7619-1:2004. The result indicated shore hardness had a enhance trendency along the additives. There was a significant difference among all groups. The density was carried out under GB9891-88. The result indicated density had a reduce trendency along the additives. There was a significant difference when MEB-PLGA-NPs reached20%.In summary, we fabricated a novel silicone elastomer pharmaceutical preparation which had a low density, anti-F.n ATCC10953activity and sustained MEB release. MEB-PLGA-NPs were prepared using single emulsion-solvent evaporation method. The MEB-PLGA-NPs were white powder with good properities of redissolve and flowing. The particles of MEB-PLGA-NPs were sphericity or subsphaeroidal characters under SEM. The cumulative release rate of MEB in vitro indicated the MEB-PLGA-NPs has a sustain release effect on MEB while the MEB-PLGA-NPs-SE has further sustain release effect than PLGA and SE. The drug sensitivity assay of MEB-PLGA-NPs-SE indicated the silicone elastomer pharmaceutical preparetions had an effective anti-bacteria activity on F.n ATCC10953, the bacteriostatic rings were22.10±0.17mm in30%MEB-PLGA-NPs-SE. Considering the sustained release of MEB from MEB-PLGA-NPs-SE, we can conclude the MEB-PLGA-NPs-SE will have a long-term anti-bacteria activity. The cell toxicity of all experiment groups indicated the MEB-PLGA-NPs-SE had a low toxicity property. The physical and mechanical properities indicated the MEB-PLGA-NPs can reduce the density of silicone elastomer significantly.