Targeting matrix metalloproteinases with intravenous doxycycline in severe sepsis--A randomised placebo-controlled pilot trial.

An overwhelming inflammatory process is the hallmark of severe sepsis and septic shock. Matrix metalloproteinases (MMPs)-8 and -9 are released from neutrophils and activated in sepsis to participate in inflammation in several ways. High levels of MMP-8 may associate with increased ICU mortality. The activity of MMP-8 and -9 is regulated by a natural inhibitor, tissue inhibitor of metalloproteinases-1 (TIMP-1). Moreover, MMPs are chemically inhibited by tetracycline-group antibiotics, such as doxycycline. We therefore aimed to study plasma concentration and MMP inhibition after intravenous doxycycline in critically ill patients with severe sepsis and septic shock in a prospective, randomised, placebo-controlled double-blinded pilot trial. Twenty-four patients with severe sepsis or septic shock were randomised in 3 groups. Group 1 received 200, 100 and 100mg, group 2 100, 50 and 50mg of intravenous doxycycline and group 3 placebo on three consecutive days. We measured doxycycline concentrations from baseline up to day 5. MMPs and TIMP-1 concentrations were measured from baseline up to day 10 of study and we compared their changes over time from baseline to 72 h and from baseline to 120 h. Data from 23 patients were analysed. At 72 h all patients in group 1 showed doxycycline concentrations >1 mg/l, whereas none in group 2 did. No serious adverse effects of the drug were recorded. We observed no differences over time up to 72 or up to 120 h in the concentrations or activities of MMP-8, -9 or TIMP-1 in any of the groups. We found intravenous doxycycline 100, 50 and 50mg to be adequate to achieve a sub-antimicrobial concentration in patients with severe sepsis or septic shock but having no impact on MMP-8, -9 or TIMP-1 concentrations or activities.