Vancomycin Dosing for Continuous Infusion
I again updated the antibiotic dosing in renal failure document. This time I added an equation to generate an expected dose for continous infusion vancomycin. The equation is (g/24h) = [0.0261 x CLcr (mg/min) + 1.78] x target Css (mg/L) x (24/1000). This is taken from Jeurissen in IntJAntimicrobAgents;37:75 2011. The equation yields the dose of vancomycin in grams/24 hours after a 1g load. Everyone gets the one gram load, but maybe just giving the standard 15mg/kg of TBW load is a better approach. There appears to be a renewed interest in continous infusion vancomycin and most articles refer to what must be the seminal article on this, a clinical trial by Wysocki AAC;45:2460 2001. Their approach was to load with 15mg/kg once over 60 minutes then initiate a 30mg/kg/24h infusion. Wysocki suggested decreasing or increasing the daily dose by 500mg increments until the desired level is achieved, which was 10—15mg/kg. This is very similar to what is suggested by NHS Tayside, Ninewells Hospital in Scotland. I do not have much occassion to use vancomycin, but am looking forward to giving this dosing a trial run. I did attempt the Wysocki method on one patient with decent results. On intermittent vancomycin dosing the patient had very high levels mixed with very low troughs and a continuously moving creatinine. Initiation of the continuous infusion vancomycin led to target levels within three days and a steady, normal creatinine. One great thing about the equation is that you can plug-in whatever Css in mg/L that you desire and out comes the anticipated vancomycin dose, so we can target levels above 25 when our MIC is greater than 1.