Release Of Vancomycin-loaded Bone Cement And Increased Release Under Influence Of Low-frequency Ulasound In Vivo

Research backgroundTreatment of infection which is difficult to cure with antibiotics-loaded bone cement has been used for a long time.Gentamycin is one of the most commonly used antibiotics in this kind of treament.While,the risk of effectiveness is increasing with the resistance to gentamycin raised.Vancomycin is more efficient in disinfecting but less of saturation than gentamycin.This seriously affects the using of vancomycin in antibiotics-loaded bone cements.Evidence showed that low-frequency ultrasonic,as a kind of physical treatment,is safe and benefit to human body, it can as well as increase the release of gentamycin loaded in cement in vivo.We try to combine the two treatments of vacomycin-loaded bone cement and low-frequency ultrasonic in this research. ObjectsTo investigate the release profile of vancomycin-loaded bone cement in vivo,so as to observe the initial quick releasing stage,the proper time of the application of low-frequency ultrasonic,as well as the potential different effect on the release in vivo,of different time and intensity of the low-frequency ultrasonic.MethodsBone cement loaded with different density of vancomycin(5%,10%) were immersed in 40ml salt solution respectively after made into the same standard ladder-shape model. Changing the salt solution for 3 times,every 24 hours of immersing once.Took samples from the salt solution in turn and determined the density of vancomycin of every sample with HPLC.After those tests,we prepared other standard ladder-shape cement models loaded with different density of vancomycin (5%10%), immersed them in 40ml salt solution.Afer immersing for 8 hours,we put the solution with cement in different intensity of low-frequency ultrasonic field for different a time respectively. Then we determine the density in 2 hours after insonation,as well as in the first 24 hours after it. ResultsRelease of vacomycin from bone cement of different density(5%,10%) both concentrated in the first 3-5 hours with the same summit. Both of the release rate of vancomycin were very low(less than 2%),while it of 10% cement showed a increasing trend after being put in the field of low intensity low-frequency ultrasonic for 30mm. ConclutionRelease of vancomycin from bone cement in vivo concentrated in the initial 3-5 hours of the first 24 hours. There was a limited increase of vancomycin lease with application of ultrasound in samples of first 24 hours. The mechanism behind these observations is not clear,but it is suggested that microstreaming or localized temperature rises may be involved.