Injectable anticoagulants are widely used in medical procedures to prevent unwanted blood clotting. However, many lack safe, effective reversal agents. Here, we present new data on a previously described RNA origami-based, direct thrombin inhibitor (HEX01). We describe a new, fast-acting, specific, single-molecule reversal agent (antidote) and present in vivo data for the first time, including efficacy, reversibility, preliminary safety, and initial biodistribution studies. HEX01 contains multiple thrombin-binding aptamers appended on an RNA origami. It exhibits excellent anticoagulation activity in vitro and in vivo. The new single-molecule, DNA antidote (HEX02) reverses anticoagulation activity of HEX01 in human plasma within 30 s in vitro and functions effectively in a murine liver laceration model. Biodistribution studies of HEX01 in whole mice using ex vivo imaging show accumulation mainly in the liver over 24 h and with 10-fold lower concentrations in the kidneys. Additionally, we show that the HEX01/HEX02 system is non-cytotoxic to epithelial cell lines and non-hemolytic in vitro. Furthermore, we found no serum cytokine response to HEX01/HEX02 in a murine model. HEX01 and HEX02 represent a safe and effective coagulation control system with a fast-acting, specific reversal agent showing promise for potential drug development.

UNASSIGNED: Fentanyl and fentanyl analogs (F/FA) have become increasingly common adulterants in counterfeit prescription pills and illicit street drug mixtures due to their ease of synthesis and exceedingly high potency. The ongoing epidemic of fatal overdoses fueled by F/FA continues to highlight the need for longer-acting therapies than naloxone (NLX), the current gold-standard for reversing opioid overdoses, which shows limited efficacy to prevent renarcotization associated with F/FA toxicity. A novel opioid reversal agent based on covalent naloxone nanoparticles (cNLX-NP) has been shown to blunt fentanyl-induced respiratory depression out to 48 hr, demonstrating its potential therapeutic utility. The purpose of this study was to characterize how rapidly cNLX-NP reverses fentanyl-induced respiratory effects as well as the duration of its protective effects.
UNASSIGNED: Sprague Dawley male rats (n=6/group) were tested on an oximeter for baseline percent arterial oxygen saturation (%SaO2) challenged with 0.1 mg/kg SC fentanyl and 15 min later given 10 mg/kg IM doses of NLX, nalmefene (NLMF), or cNLX-NP and continuously monitored via oximetry for 10 minutes. One week later the experiment was repeated using a 1:1 mixture of NLX:cNLX-NP as the reversal agent in the rats that previously received NLX alone.
UNASSIGNED: While both NLX and NLMF rapidly reversed %SaO2 to baseline within 1 min, rats that received cNLX-NP did not return to >90% SaO2 levels until 9 min after administration. Similarly, heart and breath rates returned to baseline within 1 min of treatment with NLX and NLMF but did not return to baseline until 10 minutes after cNLX-NP administration. In contrast, NLX:cNLX-NP reversed all fentanyl-induced respiratory depressive effects within one minute.
UNASSIGNED: While cNLX-NP alone may not sufficiently reverse F/FA overdose in a timely manner, mixing free NLX with cNLX-NP can provide a mechanism to both rapidly reverse fentanyl-related effects and maintain extended protection against synthetic opioid toxicity. These data support further development of cNLX-NP as a fast-acting and long-lasting antidote to treat F/FA-induced respiratory depression and overdose, and potentially prevent renarcotization in humans.

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BACKGROUND: Atipamezole, an α-2 adrenergic receptor antagonist, reverses the α-2 agonist anesthetic effects. There is a dearth of information on the physiological effects of these drugs in cynomolgus macaques (Macaca fascicularis). We assessed atipamezole\'s physiologic effects. We hypothesized atipamezole administration would alter anesthetic parameters.
METHODS: Five cynomolgus macaques were sedated with ketamine/dexmedetomidine intramuscularly, followed 45 min later with atipamezole (0.5 mg/kg). Anesthetic parameters (heart rate, blood pressure [systolic (SAP), diastolic (DAP), and mean (MAP) blood pressure], body temperature, respiratory rate, and %SpO2) were monitored prior to and every 10 min (through 60 min) post atipamezole injection.
RESULTS: While heart rate was significantly increased for 60 min; SAP, DAP, MAP, and temperature were significantly decreased at 10 min.
CONCLUSIONS: This study indicates subcutaneous atipamezole results in increased heart rate and transient blood pressure decrease. These findings are clinically important to ensure anesthetist awareness to properly support and treat patients as needed.

BACKGROUND: Despite millions of COVID-19 cases in the United States, it remains unknown whether a history of COVID-19 infection impacts the safety of pharmacologic myocardial perfusion imaging stress testing (pharmacologic MPI).
OBJECTIVE: The aim of this study was to assess if a prior COVID-19 infection was associated with a higher risk of complications during and following pharmacologic MPI testing.
METHODS: This retrospective cohort analysis included 179 803 adults (≥18 years) from the PharMetrics® Plus claims database who underwent pharmacologic MPI between March 1, 2020 and February 28, 2021. Patients with a history of COVID-19 infection (COVID-19 group) were compared with propensity-score matched no-COVID-19 history group for reversal agent use, 30-day resource use, and post-MPI cardiac events/procedures.
RESULTS: The most commonly used stress agent was regadenoson (91.7%). The COVID-19 group (n = 6372; 3.5%) had slightly higher: reversal agent use (difference 1.13% [95% confidence interval [CI]: 0.33, 1.92]), all-cause costs (difference USD $128 [95% CI: $73-$181]), and office visits (81.5% vs. 77.0%) than the no-COVID-19 group. Prior COVID-19 infection did not appear to impact subsequent cardiac events/procedures.
CONCLUSIONS: COVID-19 history was associated with slightly higher reversal agent use, all-cause costs, and office visits after pharmacologic MPI; however, the differences were not clinically meaningful. Concerns for use of stress agents in patients with prior COVID-19 do not appear to be warranted.

Factor Xa (FXa) inhibitors are widely used for stroke prevention in patients with nonvalvular atrial fibrillation, and for the treatment and prevention of deep venous thrombosis and pulmonary embolism. Compared with warfarin, individual FXa inhibitors are associated with a lower risk of major bleeding. Nevertheless, bleeding remains a feared complication of any anticoagulant therapy. Despite their demonstrated safety, implementation of FXa inhibitors in clinical practice may have been limited by the lack of a specific antidote. Recently, however, the United States Food and Drug Administration and the European Medicines Agency approved andexanet alfa for reversal of anticoagulation in patients treated with rivaroxaban or apixaban who have life-threatening or uncontrolled bleeding. This review will discuss andexanet alfa\'s mode of action, indication for use and efficacy, with a focus on its appropriate use in clinical practice. Unnecessary usage should be prevented as this may compromise patient safety. Assessment of potentially suitable patients by a multidisciplinary team, use according to the institutional protocol and central storage, all contribute to proper use of andexanet alfa. A practical tool to direct appropriate use of andexanet alfa is proposed.

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To investigate and describe the protocolized treatment of DOAC-related bleeds in all Dutch hospitals.
From August to December 2020 a nationwide survey among all 70 hospitals in the Netherlands was conducted on their protocols for management of bleeding in patients treated with direct oral anticoagulants (DOACs, i.e. apixaban, edoxaban, rivaroxaban and dabigatran). The protocols were assessed the following characteristics: bleeding definitions (mild, moderate and severe bleed), diagnostic parameters (hemoglobin [Hb], loss of blood, surgical procedure needed, etc), first and second choice of treatment, effectiveness criteria and the level of evidence/references upon which protocols were based.
All 70 hospitals responded (100%). We received 69 protocols in total, 6 of which were identical because hospitals worked together. In 35 (50%) of the protocols a definition of minor, moderate or severe bleeds was described. Diagnostic parameters for bleeds were present in 2%, 41% and 47% of protocols for a mild, moderate and severe bleed. While the first choice treatment for severe bleeding under dabigatran was idarucizumab in 96% of protocols, considerably more therapeutic options (mostly different prothrombin complex concentrate (PCC) doses) are described for Xa inhibitors. When considering criteria for effectiveness more than 90% of protocols did not have a clear description.
This study provides an overview of the current state of protocols for management of DOAC-related bleeding in The Netherlands. Protocols vary in the content of information provided and often do not include information, especially for diagnostic criteria and criteria for establishing the effectiveness of the intervention. The results of this study can assist in improving and harmonizing the protocols.

Overexpression of ABCG2 transporter in cancer cells has been linked to the development of multidrug resistance (MDR), an obstacle to cancer therapy. Our recent study uncovered that the MET inhibitor, tepotinib, is a potent reversal agent for ABCB1-mediated MDR. In the present study, we reported for the first time that the MET inhibitor tepotinib can also reverse ABCG2-mediated MDR in vitro and in vivo by directly binding to the drug-binding site of ABCG2 and reversibly inhibiting ABCG2 drug efflux activity, therefore enhancing the cytotoxicity of substrate drugs in drug-resistant cancer cells. Furthermore, the ABCB1/ABCG2 double-transfected cell model and ABCG2 gene knockout cell model demonstrated that tepotinib specifically inhibits the two MDR transporters. In mice bearing drug-resistant tumors, tepotinib increased the intratumoral accumulation of ABCG2 substrate drug topotecan and enhanced its antitumor effect. Therefore, our study provides a new potential of repositioning tepotinib as an ABCG2 inhibitor and combining tepotinib with substrate drugs to antagonize ABCG2-mediated MDR.

Reversal agents are defined as any drug used to counteract the pharmacologic effects of another drug. Several pharmacologic antagonists serve as essential drugs in the contemporary practices of sedation providers and anesthesiologists. Reversal or \"antidote\" drugs, such as flumazenil and naloxone, are often used in unintentional overdose situations involving significant benzodiazepine- and/or opioid-induced respiratory depression. Within the context of skeletal muscle relaxation, neostigmine and sugammadex are routinely used to reverse the effects of nondepolarizing neuromuscular blocking agents. In addition, the alpha-adrenergic antagonist phentolamine is used in dentistry as a local anesthetic reversal agent, decreasing its duration of action by inducing vasodilation. This review article discusses the pharmacology, uses, practical implications, adverse effects, and precautions needed for flumazenil, naloxone, neostigmine, sugammadex, and phentolamine within the context of sedation and anesthesia practice for dentistry.