Venous sequelae following i.v. administration of diclofenac

Diclofenac sodium (Voltarol) was administered i.v. to 149 consecutive patients who were thought likely to benefit from its anti-inflammatory action. Patients were allocated randomly to one of two groups: group A received the undiluted i.m. preparation (25 mg ml-1) and group B the i.m. preparation diluted in normal saline (5 mg ml-1). Diclofenac 1 mg kg-1 administered over a 10-min period via a 23-gauge needle into a vein at either the antecubital fossa or the dorsum of the hand. No local or systemic problems were encountered in either group, at the time of injection. A high incidence of painless local venous thrombosis occurred in both hand and arm veins, 72 h after administration in group A (85% and 58%, respectively). The incidence of thrombosis was reduced markedly after administration of the diluted drug: 38% hand veins; 8% antecubital fossa veins.