When administering IV vancomycin and IV gentamicin for endocarditis prophylaxis in high-risk patients who are allergic to ampicillin/amoxicillin, the instruction is to “complete infusion within 30 minutes of starting procedure.” Does that mean one should wait at least 30 minutes before starting the procedure? Is starting two hours after the infusion acceptable? Or must the procedure be started within the first 30 minutes after the vancomycin/gentamicin infusion is completed? For example, after 10 minutes but not 40 minutes.
—Charles Liang, DO, Bloomington, Ill.
Bearing in mind that the infusion of vancomycin should take at least one hour and that of gentamicin should take 30 minutes, these recommendations mean that one should allow two hours for infusion before the procedure start time. A slight delay will not have any significant impact. Peak concentrations occur 30 minutes after infusion, and both antibiotics have sufficient half-lives that prophylaxis will last for several hours. Therefore, most high-risk procedures can be completed with reduced risk for endocarditis. If the procedure lasts longer than eight hours, a second infusion of gentamicin could be given.
—Cedric W. Spak, MD, MPH (113-16)