Blood coagulation changes in response to dexamethasone in the normal rat

ABSTRACT

The effect of daily dexamethasone on blood coagulation was studied in normal male rats. Dexamethasone was injected daily [0.4 mg/kg body weight] for 3 weeks. Blood was collected retro-orbitally from the rats before and after 2 days, after 1 week and after 3 weeks of dexamethasone administration. Prothrombin time [PT], fibrinogen [FIB] and activated partial thromboplastin time [APTT] were determined in plasma. Results were compared with the values found in normal adult male rats before injections [controls]. It was found that dexamethasone significantly increased the FIB already after 2 days of administration, while it significantly decreased APTT starting after one week of dexamethasone injections. PT, however, remained unaffected by dexamethasone throughout the time of the study. From these results, it can be concluded that dexamethasone does not seem to affect the extrinsic coagulation cascade, but increases procoagulant activity via the intrinsic pathway. Also, decreased fibrinolysis was recorded, as witnessed by increased fibrinogen levels. Thus, glucocorticoids should be prescribed with caution in patients with hypercoagulable states