Prior to the approval of andexanet, there were no FDA-approved reversal agents indicated for the treatment of factor Xa inhibitor (FXaI) associated major bleed. Four-factor prothrombin complex concentrate (4F-PCC) has been widely used off-label for FXaI-associated bleeding. The purpose of this study was to compare the effectiveness and safety of andexanet and 4F-PCC for the reversal of FXaI-associated intracranial haemorrhage. The primary end point is in-hospital mortality; secondary endpoints include haemostatic efficacy and safety. This study is a singlecentre, retrospective chart review, including patients admitted between 1 January 2016 and 15 August 2019, who received 4F-PCC or andexanet for the management of FXaI-associated intracranial haemorrhage. Of the 45 patients included in this study, 23 patients were in the andexanet group and 22 were in the 4F-PCC group. At index admission, mean age was 76 years and the majority of patients (64%) were on apixaban with 33% presented with Glasgow Coma Scale 24 (GCS) score less than 12. At hospital discharge, 47% of patients in the andexanet group had died or discharged to hospice compared with 45% in the 4F-PCC group. No thromboembolic events were observed in either group within 5 days after administration of the reversal agent. The results of this study suggest that haemostasis and mortality at discharge during the index hospitalization appears to be similar between groups. Prospective randomized control trials comparing safety and efficacy of andexanet and 4F-PCC are needed.

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DOPAC, the major intermediate metabolite of dopamine, is found in the cytosolic compartment of dopaminergic terminals/varicosities and in the extracellular space. It has been proposed that extracellular DOPAC is derived from newly synthesized dopamine rather than from dopamine in the signaling pool. On the basis of literature data supporting such a concept, we hypothesize a DOPAC synthesis/secretory complex producing extracellular DOPAC and use a computational simulation model of dopaminergic varicosities to estimate the distribution of DOPAC between cytosolic and extracellular compartments, amount of newly synthesized dopamine entering the DOPAC synthesis/secretory complex, and potential regulatory processes in the complex. Results suggest that about two-thirds of DOPAC is in the extracellular space. Approximately one-third of newly synthesized dopamine is immediately processed to DOPAC, which is then secreted into extracellular space. Extracellular DOPAC concentration is approximately 300 times higher than extracellular dopamine, and cytosolic DOPAC is ∼18-fold higher than cytosolic dopamine. We suggest that the high levels of extracellular DOPAC coupled with evidence for its production from newly synthesized dopamine imply the existence of an as yet undiscovered regulatory/signaling role for DOPAC.

Traumatic brain injury (TBI) is a leading cause of disability in the United States. With decreasing mortality rates, a higher number of patients are impacted by long-term neuropsychiatric sequelae, such as cognitive deficits, depression, anxiety, and sleep-wake disorders. These sequelae are primarily driven by the disruption of key neurotransmitter homeostasis including dopamine, norepinephrine, serotonin, and acetylcholine. Neurostimulants are centrally acting medications used to assist in restoring these neurotransmitter abnormalities and are pharmacologic options to ameliorate symptoms in post-TBI patients. Examples of neurostimulants include amantadine, selective serotonin reuptake inhibitors, tricyclic antidepressants, central stimulants (ie, methylphenidate), modafinil, and donepezil. Large, well-powered studies have not been performed to validate their use in patients with TBI, leaving uncertainty for these agents' place in therapy. Current practice is driven by consideration of patient-specific factors to select the most appropriate agent. This review provides clinicians with a summary of the available literature on neurostimulants following TBI to guide appropriate usage to help improve patients' symptoms and optimize safety.