Limited data exist regarding the pharmacokinetics of doxycycline, while none are available with use of extracorporeal membrane oxygenation (ECMO). Here, we present a novel study of the pharmacokinetics of doxycycline in a rare case of severe plasmodium falciparum malaria associated acute respiratory distress syndrome (ARDS) requiring venovenous ECMO support. Our case involved a young 24 year-old gentleman who presented with plasmodium falciparum malaria after a trip to Nigeria in the setting of noncompliance with chemoprophylaxis while abroad. As he clinically deteriorated, eradication of parasitemia was achieved with the use of intravenous quinidine. Once on venovenous ECMO, intravenous doxycycline (100mg every 12 hours) was used to prevent recrudescence. In the venovenous ECMO circuit, venous blood was removed from the vena cava and passed through tubing consisting of a hydrophilic, negatively charged polymer coated with heparin, a single-use centrifugal pump generating the flow rate, and a polymethylpentene membrane oxygenator with integrated heat exchanger, prior to being returned to the body to the right atrium. Methods:
Total plasma doxycycline levels were drawn at various time points after steady state concentration was reached. Doxycycline concentration was determined by HPLC with a mean reference range of 2.7 – 4.5 mcg/mL for a peak and 1.6 for a trough when standardized to a 200 mg dose. Pharmacokinetic parameters were calculated using standard formulae, and AUC was calculated using the log-linear trapezoidal rule (Figure 1).
Our results demonstrate that a doxycycline dose of 100 mg every 12 hours was effective in prevention of recrudescence of parasitemia, and that the ECMO circuit did not result in decreased doxycycline levels. These findings indicate that there is no dose adjustment necessary, for administration of intravenous doxycycline while on ECMO.
According to our PK data, doxycycline can be used without dose adjustment in patients on ECMO. As the technology of oxygenation and circulatory support, like ECMO, advances and disseminates, it is imperative that we follow along with studies of pharmacokinetics of antimicrobials to beat the microbes while keeping up with modern technology.
K. Beaulac, None
R. Roberts, None