In vitro paraoxon (E 600) exposure: no activating effect on human blood coagulation

The in vitro effects of the organophosphorus compound (OPC) paraoxon (POX) on human blood coagulation were assessed by fibrin monomer (FM) concentration measurements and thrombelastographic (TEG) determinations. Increasing doses of POX dissolved in alcohol (POX + ALO) or alcohol (ALO) only in corresponding quantities were added to blood drawn from six human volunteers. In both series (POX + ALO and ALO-only) FM concentrations increased in comparison to the baseline levels. No statistically significant differences exist, however, between FM measurements performed on blood with POX + ALO and those performed on blood with ALO-only. No coagulation-activating effect of POX in vitro was demonstrable; the changes seen in vitro are due to the ALO used as a vehicle. The thrombelastographic parameters showed several changes in the POX + ALO series as dosage increased. At high POX levels, reaction time r and clot formation time k became longer than in the baseline measurements, the clot formation rate alpha and the maximum amplitude MA were reduced. The TEG changes indicate a hypocoagulable state, probably due to the POX effect on platelet function and/or inhibition of clotting factors (serine proteases).