Prothrombotic effect of Rofecoxib in a murine venous thrombosis model.

The potential prothrombotic effect of the cyclooxygenase-2 (COX-2) inhibitor Rofecoxib (Vioxx) was investigated using murine thrombosis models. In a jugular vein thrombosis model (photochemically induced injury) in lean wild-type mice, Rofecoxib treatment for 4 weeks induced a mild prothrombotic tendency, as indicated by a shorter occlusion time as compared to placebo (median of 12 min versus 36 min; p < 0.05). Thrombus size was somewhat, but not significantly, enhanced after Rofecoxib treatment. In a femoral artery thrombosis model (FeCl3 induced injury) Rofecoxib did not cause an enhanced thrombotic tendency in mice with nutritionally induced or genetically determined (ob/ob) obesity. The occlusion time was comparable for obese wild-type mice with (8.8+/-0.7 min) or without (7.8+/-2.1 min) Rofecoxib treatment, as well as for ob/ob mice (8.5+/-0.7 min versus 6.8+/-3.0 min). Thus, an enhanced prothrombotic effect of Rofecoxib was detected when using a venous thrombosis model in lean mice, but not when using an arterial thrombosis model in obese mice.