Evaluation of phenytoin loading doses in overweight patients using actual versus adjusted body weight.

BACKGROUND AND OBJECTIVES: The appropriate loading dose strategy for phenytoin/fosphenytoin in overweight patients is unknown. A small pharmacokinetic study indicated that overweight patients have a higher volume of distribution and potentially would benefit from using adjusted body weight (AdjBW) instead of actual body weight (ABW) to calculate the loading dose. The purpose of this study was to determine the optimal loading dose strategy of phenytoin in patients whose ABW is greater than 120% of their ideal body weight (IBW) using either ABW or AdjBW for calculation of the loading dose. METHODS: This was a single center, retrospective study which included patients who received a loading dose of phenytoin of at least 10 mg/kg based on ABW, had a phenytoin level drawn <6 h after the end of the dose, and weighed ≥120% of their IBW. Patients were excluded if they received intramuscular phenytoin or fosphenytoin or were prescribed phenytoin prior to the loading dose. Patients were divided into two groups, those who were dosed using their AdjBW versus those dosed using ABW. The primary outcome was achievement of therapeutic phenytoin level of 10-20 mcg/mL. Secondary outcomes included achievement of a subtherapeutic or supratherapeutic level. RESULTS: A total of 195 patients (128 in AdjBW group and 67 in ABW group) met criteria for inclusion. Patients in the AdjBW group weighed more (96.2 kg vs. 91.2 kg, p = 0.04) and received a lower dose in milligrams (1364 vs. 1760, p < 0.0001) and in mg/kg of ABW (14.2 vs. 19.3, p < 0.0001). The primary outcome was achieved in 74% of patients in the AdjBW group and 57% of patients in the ABW group (p = 0.02). Patients in the ABW group were more likely to have a supratherapeutic level (43% vs. 22%, p = 0.003), although adverse reactions did not differ between the groups. DISCUSSION: Patients weighing >120% of their IBW (average body mass index 33.5 kg/m2) who received a 20 mg/kg loading dose based on AdjBW were more likely to achieve a therapeutic phenytoin concentration compared to those dosed based on ABW. Further research is needed to correlate this finding with clinical outcomes, such as resolution of status epilepticus.

Inactivated Four-Factor Prothrombin Complex Concentrate Dosing Practices for Reversal of Warfarin-Related Intracranial Hemorrhage.

BACKGROUND/OBJECTIVE: Inactivated four-factor prothrombin complex concentrate (I4F-PCC, Kcentra®) has become an important agent for the urgent or emergent reversal of bleeding associated with vitamin K antagonists such as warfarin. There is recognized inter-institutional variability with the use of I4F-PCC, especially as it relates to dosing practices. We sought to characterize variations in I4F-PCC dosing practices and their impact on patient outcomes and describe overall real-world clinical practice surrounding I4F-PCC utilization in the context of the management of warfarin-related intracranial hemorrhage (ICH). METHODS: This is a multicenter retrospective pragmatic registry study of adult patients admitted at a participating study site between January 1, 2014, and December 31, 2015, who received I4F-PCC for reversal of warfarin-related ICH. Practices around warfarin-related ICH reversal in context of I4F-PCC utilization are described, including repeat I4F-PCC dosing, adjunctive reversal agents, and dose rounding policies (i.e., rounding doses to nearest vial size vs preparing exact/unrounded doses). All research was approved by local human investigation committees at each institution. RESULTS: Seventeen institutions contributed data on 528 patients to this registry. These institutions were primarily urban centers (74%), located in the southeast USA (47%), with Level 1 Trauma designation (79%), and with Comprehensive Stroke Center designation (74%). Most patients included in the study had sustained a non-traumatic ICH (68%), had a median admission GCS of 14 (IQR 7-15), and were receiving warfarin for atrial fibrillation (57.4%). There was substantial time latency between baseline INR and I4F-PCC (median 2.4 h, IQR 1.4-4.5 h). Most patients received adjunctive reversal agents, including vitamin K (89.5%) and fresh frozen plasma (FFP) (31.9%). A smaller proportion (6.0%) of patients received repeat I4F-PCC dosing. The median ICU length of stay (LOS) was 3 days (IQR 2-7 days), median hospital LOS was 6 days (IQR 3-12 days), and overall mortality rate was 28.8%. For institutions rounding doses to the nearest vial size, the first post-I4F-PCC dose INR was statistically but not clinically significantly lower than for institutions without vial size dose rounding, with comparable degrees of INR reduction from baseline. No differences were observed between dose rounding cohorts in adverse effects, ICU or hospital LOS, modified Rankin score at discharge, or mortality rates. CONCLUSIONS: Most patients received single doses of I4F-PCC, with adjunctive reversal agents and rounding doses to vial size. The time difference from baseline INR to factor product administration is a potential opportunity for process improvement in the management of warfarin-related ICH.

Clinical experience with three-factor prothrombin complex concentrate to reverse warfarin anticoagulation in intracranial hemorrhage.

BACKGROUND AND PURPOSE: The effectiveness of prothrombin complex concentrate (PCC) products available in the United States that contain low levels of factor VII (3-factor PCC) has not been tested. The purpose of this study was to review our experience with 3-factor PCC (Profilnine) in the setting of warfarin-associated intracranial hemorrhage (wICH). METHODS: In November 2007, we implemented a protocol for reversal of anticoagulation in wICH using Profilnine. Additional treatment with fresh-frozen plasma was at the discretion of the treating physician. Medical records of all patients receiving PCC for wICH between November 1, 2007, and December 7, 2011 were reviewed. Correction of the international normalized rate (INR) was defined as an INR <1.4. RESULTS: Seventy wICH patients were treated with Profilnine, including 46 (66%) with intraparenchymal hemorrhage, 22 (31%) with subdural hemorrhage, and 2 (3%) with subarachnoid hemorrhage. Mean INR was reduced from 3.36 to 1.96, and in 44 (62.9%) patients the INR corrected to <1.4. Baseline INR ≥3.0 decreased the likelihood of INR correction. Concomitant administration of fresh-frozen plasma (mean, 2.6 U) did not increase the likelihood of INR correction. Seven (10%) patients had serious adverse events during their hospital course, including 2 sudden deaths from suspected pulmonary embolism. CONCLUSIONS: Reversal of coagulopathy in wICH with Profilnine was incomplete and associated with serious adverse events. In the absence of available 4-factor PCC, options for urgent reversal of anticoagulation in wICH remain limited.