Intravenous vitamin K at a dose of 0.5 mg achieved an optimal INR response (2-4 at day 1) in 67% of patients, compared to 33% of those receiving 1 or 2 mg.
RCT (n=24)
randomized
Does a specific dose of intravenous vitamin K (0.5 mg, 1 mg, or 2 mg) optimize INR reversal in asymptomatic or mildly haemorrhagic patients on warfarin with INR > 7.0?
A 0.5 mg dose of intravenous vitamin K provides optimal INR reversal for most asymptomatic over-warfarinized patients, avoiding the overcorrection seen with 1 mg or 2 mg doses.
Absolute Event Rate: 67% vs 33%
The optimal management of asymptomatic overanticoagulated patients remains unknown. We measured international normalized ratio (INR), activated partial thromboplastin time (APTT) and prothrombin fragment 1 + 2 (F1 + 2) over 7 d in 24 asymptomatic or mildly haemorrhagic patients on warfarin with prolonged INR of > 7.0 who were randomized to receive 0.5 mg, 1 mg or 2 mg intravenous vitamin K. Of six severely overanticoagulated patients (INR > 9.5 with APTT ratio > 2), five failed to achieve an INR < or = 4.0 on day 1, irrespective of vitamin K dose given. In the remaining 18 cases, an optimal response (INR 2-4 at day 1) was observed in 67% of those receiving 0.5 mg vitamin K, but only in 33% of those receiving 1 or 2 mg, the majority of whom developed an INR < 2.0. Our results support an optimal dose of 0.5 mg i.v. vitamin K for most overanticoagulated patients, with possibly a repeat dose in the small group of severely overanticoagulated patients.
Hung et al. (Thu,) conducted a rct in Over-warfarinization (n=24). Intravenous vitamin K vs. 1 mg or 2 mg intravenous vitamin K was evaluated on Optimal response (INR 2-4 at day 1). Intravenous vitamin K at a dose of 0.5 mg achieved an optimal INR response (2-4 at day 1) in 67% of patients, compared to 33% of those receiving 1 or 2 mg.