Successful Protein C Concentrate Administration during Initiation of Oral Anticoagulation in Adult Patients with Severe Congenital Protein C Deficiency: Report of Two Cases

Protein C (PC) is a vitamin K-dependent proenzyme with anticoagulant activity, and patients with congenital PC deficiency are at high risk for thrombotic episodes. In patients with PC deficiency, starting treatment with oral anticoagulant drugs is associated with a transient hypercoagulable state and clinically overt thromboembolic complications before reaching a full anticoagulant effect. This report describes a successful supplementation with PC concentrate in two adult patients with moderately severe PC deficiency during the initiation of oral anticoagulation and a course of therapeutic dose of low-molecular-weight heparin for acute venous thromboembolism. Plasma PC levels above 50% were observed in both patients and maintained during the entire supplementation treatment period with PC concentrate until a stable therapeutic anticoagulation level has been reached. These results have been obtained within a short time, thus allowing a safe administration of a loading dose of warfarin. No adverse reactions to the PC concentrate, i.e. skin necrosis and other thromboembolic complications, bleedings or allergic reactions, were observed. We conclude that PC concentrate seems to be effective for the prevention of thromboembolic complications and safe in patients with congenital PC deficiency while initiating oral anticoagulants.