Phenytoin, Nifedipine, And Cyclosporin Loaded PLGA Microspheres, Used As Controlled Release Delivery System, Promote Periodontal Regeneration

Part 1 An animal model of drug induced gingival hyperplasia on ratsObjectives:To establish an animal model of drug induced gingival hyperplasia. We selected SD rats as the experimental animals.Methods:We chose two typical drugs, namely antiepileptic phenytoin and calcium channel blocker nifedipine. All the rats were fed with the phenytoin or nifedipine orally.The medication time was set to 25 days, 50days, and 75 days, and once a day. After the administration time, rats were sacrificed, maxillary bone and periodontal tissue were collected, then observe and measure the gingival width. After these, tissues were formalin fixed and paraffin embedded, immunohistochemistry and analyze the results.Results:After a long term administration of phenytoin or nifedipine, the rats'gingiva showed obvious overgrowth (P<0.01 or p<0.05). The gingival width grew and the pegs in gingival epithelium extend remarkably.Conclusion:Long term use of antiepileptic phenytoin and calcium channel blocker nifedipine may induce gingival hyperplasia on rats.Part 2 Gingival local administration on ratsObjectives:Phenytoin solution was locally injected into the gingival tissue, then we observed the role phenytoin had played on affecting SD rats' gingiva.Method:SD rats were generally anaesthetized. Phenytoin solution was locally injected into the buccal side of maxillary first molar once a day. The dosage was 20ul per injection.40 days later, all of the rats were sacrificed. We observed and analyzed the change of rats'gingiva.Results:Data shows that rats'gingiva didn't overgrow after locally injected phenytoin solution. There was no significant difference between the the study group and control group (p>0.05).Conclusion:It is not a good idea to induce gingival hyperplasia with local injection of phenytoin solution.Part 3 A research on phenytoin, nifedipine, cyclosporine loaded PLGA microspheres promote periodontal tissue regenerationObjectives:Phenytoin, Nifedipine, Cyclosporine are three drugs that may induce gingival hyperplasia.They are typical drugs of antiepileptic drugs, calcium channel blockers, and immunosuppressor. We delivered these drugs into rats'gingival recession models with a kind of biocompatible absorbale materials PLGA, in the form of controlled release delivery. Then we can know the therapeutic effect of these drugs to gingival recession and alveolar resorption.Methods:1. Prepare Phenytoin, Nifedipine and Cyclosporine loaded PLGA microspheres and blank control, namely PHT-PLGA,NIF-PLGA,CSA-PLGA,and PBS-PLGA.2. We detected the three kinds of microspheres with an external release experiment to confirm drug content, concentration and release time.3. Prepare animal models of gingival recession on SD rats.4. We delivered the three kinds of microspheres into the defects made in step3,2 months later all the rats were sacrificed. We observed rats' gingiva with stereoscopic microscope, then observed rats'alveolar regerneration with micro-CT, then all the tissue specimens were paraffin embedded sectioned. Finally we detected osteoblast, osteoclasts and type I collagen fiber with IHC.Results:1. Microspheres were successfully prepared. The morphology under scanning electron microscope is good, and consistent with the literature description.2. HPLC analysis showed that Phenytoin group and Nifedipine group maintain a long-term high concentration when the drug was released, but not for Cyclosporine group.3. Animal model of gingival recession on rats was successfully established.4. The Phenytoin and Nifedipine microspheres promote rats'alveolar regeration and gingival regenaration, but cyclosporine does not show similar effect. Above all, phenytoin shows significant effect on alveolar and gingival regenartion (p<0.01), and the laboratory result is the most conspicuous one.Conclusion:1. Phenytoin can be used in the treatment of gingival recession and alveolar resorption, and we should pay more atthention to this drug.2. PLGA microspheres, as a kind of drug carrier with good biocompatibility and tiny size, may be quite suitable for the treatment of periodontal defect. It will be a very promising carrier in the field.