Hydrochloride Doxycycline Injected Into The Gel And Its Bio-pharmaceutical Research

The preparation of an extended release injectable gel containing doxycycline hyclate (DoxHcl)using poly lactic acid(PLA) and copolymer of poly lactic and glycolic acid(PLGA) was studied. Physical梒hemical properties of PLA and PLGA such as intrinsic viscosity [ii] solubility and glass transition temperature (Tg) were determined. The effects of the type of PLA /PLGA and the cOntent of PLA/PLGA in its gel solution on the drug release was studied. The description was optimized by orthogonal factorial design. A polymeric injectable gel delivery system containing DoxHcl from which drugs can release for 7 days was made. This gel will be injected into periodontal pockets for periodontal diseases. The effects of drug contents, release medium and release apparatus on the drug release was studied. Two analysis methods was developed to determine DoxHci contents in the preparation: one is ultraviolet梫isible spectrophotometric method and another is high梡erformance liquid chromatographic method. The stability of DoxHcl solution was studied under 3500 Lux light.. 800C.. 370C and ambient temperature. After in vitro drug release study, in vivo study was carried out in healthy gingivae of rabbits. HPLC was used to analyze the residue drug contents in rabbit gingivae. The gingival injection delevery way was compared with oral administration. DoxHcl concentrations in rabbit plasa and saliva were determined by HPLC after injection and oral administration. The results show that DoxHcl release much faster from gel made of low molecular PLA/PLGA, low content of PLA/PLGA and high content of drugs. In acid release medium and flow cell, DoxHcl release more faster 2 than that in water and 370C shaking water bath. Both in vitro and in viva studies indicate that DoxHcl gel can maintain doxycycline upper than its MIC for 7 days. DoxHcl solution was unstable under 800C and 3500 Lux light, but more stable in 370C for 7 days and ambient temperature for 10 days. Rabbit?s saliva concentration of DoxHcl after gingival injection were largely higher than that of orally administration of DoxHcl tablets. On the contrary, the plasa concentration of DoxHcl after gingival injection were largely lower than that of orally administration of DoxHcl tablets. It can be concluded that DoxHcl can continuously release from the preparation for 7 days. This gel is more suitable for patients with periodontitis than tablets and other oral preparations, especially for chronic adult periodontitis.