Warfarin analogs target disulfide bond-forming enzymes and suggest a residue important for quinone and coumarin binding.

Disulfide bond formation has a central role in protein folding of both eukaryotes and prokaryotes. In bacteria, disulfide bonds are catalyzed by DsbA and DsbB/VKOR enzymes. First, DsbA, a periplasmic disulfide oxidoreductase, introduces disulfide bonds into substrate proteins. Then, the membrane enzyme, either DsbB or VKOR, regenerate DsbA's activity by the formation of de novo disulfide bonds which reduce quinone. We have previously performed a high-throughput chemical screen and identified a family of warfarin analogs that target either bacterial DsbB or VKOR. In this work, we expressed functional human VKORc1 in Escherichia coli and performed a structure-activity-relationship analysis to study drug selectivity between bacterial and mammalian enzymes. We found that human VKORc1 can function in E. coli by removing two positive residues, allowing the search for novel anticoagulants using bacteria. We also found one warfarin analog capable of inhibiting both bacterial DsbB and VKOR and a second one antagonized only the mammalian enzymes when expressed in E. coli. The difference in the warfarin structure suggests that substituents at positions three and six in the coumarin ring can provide selectivity between the bacterial and mammalian enzymes. Finally, we identified the two amino acid residues responsible for drug binding. One of these is also essential for de novo disulfide bond formation in both DsbB and VKOR enzymes. Our studies highlight a conserved role of this residue in de novo disulfide-generating enzymes and enable the design of novel anticoagulants or antibacterials using coumarin as a scaffold.

Updated Assessment of Practice Patterns of Perioperative Management of Antiplatelet and Anticoagulant Therapy in Interventional Pain Management.

BACKGROUND: The role of antiplatelet/anticoagulant therapy is well known for its primary and secondary prevention of sequela from cardiovascular disease by decreasing the incidence of acute cerebral, cardiovascular, peripheral vascular, and other thrombo-embolicevents. The overwhelming data show that the risk of thrombotic events is significantly higher than that of bleeding during surgery after antiplatelet drug discontinuation. It has been assumed that discontinuing antiplatelet therapy prior to performing interventional pain management techniques is a common practice, even though doing so may potentially increase the risk of acute cerebral and cardiovascular events. A survey of practice patterns was conducted in 2012, since then the risks associated with thromboembolic events and bleeding, has not been systematically evaluated. OBJECTIVE: To conduct an updated assessment of the perioperative antiplatelet and anticoagulant practice patterns of U.S. interventional pain management physicians and compare this with data collected in 2012 with 2021 data regarding practice patterns of continuing or discontinuing anticoagulant therapy. STUDY DESIGNn: Postal survey of interventional pain management physicians. STUDY SETTING: Interventional pain management practices in the United States. METHODS: The survey was conducted based on online responses of the members of the American Society of Interventional Pain Physicians (ASIPP) in 2021. The survey was designed similar to the 2012 survey to assess updated practice patterns. RESULTS: The questionnaire was sent out to 1,700 members in October 2021. Out of these, 185 members completed the survey, while 105 were returned due to invalid addresses. The results showed that 23% changed their practice patterns during the previous year. The results also showed that all physicians discontinued warfarin therapy with the majority of physicians accepting an INR of 1.5 as a safe level. Low dose aspirin (81 mg) was discontinued for 3 to 7 days for low-risk procedures by 8% of the physicians, 34% of the physicians for moderate or intermediate risk procedures, whereas they were discontinued by 76% of the physicians for high-risk procedures. High dose aspirin (325 mg) was discontinued at a higher rate. Antiplatelet agents, including dipyridamole, cilostazol, and Aggrenox (aspirin, extended-release dipyridamole) were discontinued from 3 to 5 days by 18%-23% of the physicians for low-risk procedures, approximately 60% of the physicians for moderate or intermediate-risk procedures, and over 90% of the physicians for high-risk procedures. Platelet aggregation inhibitors clopidogrel, prasugrel, ticlopidine, and ticagrelor were discontinued for 3 to 5 days by approximately 26% to 41% for low-risk procedures, almost 90% for moderate or intermediate-risk procedures, and over 97% for high-risk procedures. Thrombin inhibitor dabigatran was discontinued by 33% of the physicians for low-risk procedures, 92% for moderate or intermediate-risk procedures, and 99% for high-risk procedures. Anti-Xa agents, apixaban, rivaroxaban, and Edoxaban were discontinued in over 25% of the physicians for low-risk procedures, approximately 90% for moderate or intermediate-risk procedures, and 99% for high-risk procedures. LIMITATIONS: This study was limited by its being an online survey of the membership of one organization in one country, that there was only a 11.6% response rate, and the sample size is relatively small. Underreporting in surveys is common. Further, the incidence of thromboembolic events or epidural hematomas was not assessed. CONCLUSION: The results in the 2021 survey illustrate a continued pattern of discontinuing antiplatelet and anticoagulant therapy in the perioperative period. The majority of discontinuation patterns appear to fall within guidelines.

Frecuencia de sangrado en pacientes con enfermedades cardiovasculares anticoagulados con warfarina genérica vs. Coumadin / Frequency of bleeding in patients with cardiovascular disease on anticoagulant therapy with generic warfarin vs. Coumadin

Objetivos: comparar la frecuencia de complicaciones hemorrágicas en pacientes mayores de dieciocho años con enfermedades cardiovasculares que se encuentren anticoagulados con warfarina genérica y en aquellos anticoagulados con Coumadin. Metodología: se realizó un estudio de cohortes de tipo retrospectivo, se tomó una muestra total de 444 pacientes, 222 en terapia con warfarina genérica y 222 en terapia con Coumadin. Resultados: en la muestra de 444 se conoció el género en 406 pacientes, 187 (46.1%) fueron mujeres y 219 (53.9%) hombres. Los diagnósticos más frecuentes por los cuales los pacientes se encontraban anticoagulados fueron reemplazo valvular 265 pacientes y fibrilación auricular 123 pacientes. De todos los pacientes presentaron alguna complicación 194. Al momento de la complicación se encontraban en tratamiento con warfarina genérica 152 pacientes (78.4%) y 42 pacientes se encontraban en tratamiento con Coumadin (21.6%). De los 194 pacientes que presentaron complicaciones, 114 (58.76%) presentaron algún episodio de sangrado. De ellos, presentaron sangrado mayor siete pacientes y sangrado menor 107 pacientes.. Después de la complicación cambiaron de medicamento 47 pacientes, de los cuales lo hicieron de warfarina genérica a Coumadin 39 pacientes, de los cuales mejoraron 94.9% y de Coumadin a warfarina genérica ocho pacientes, con mejoría sólo en 12.5%. Conclusiones: la frecuencia de episodios de sangrado menor es significativamente mayor entre los pacientes anticoagulados con warfarina genérica que en los anticoagulados con Coumadin. Además en los pacientes que presentaron alguna complicación, se observó una mejoría significativa con el cambio de warfarina genérica a Coumadin (Acta Med Colomb 2010; 35: 175-178).

Objectives: to compare the frequency of bleeding complications in patients older than 18 years with cardiovascular diseases on anticoagulant therapy with generic warfarin with that of patients receiving Coumadin, and thus to obtain information allowing optimization of treatment for these patients. Methodology: a retrospective cohort study that examined a sample of 444 patients; 222 of them were in therapy with generic warfarin, and the remaining 222 with Coumadin. Results: it was possible to establish the age of 284 patients of the 444 included in the sample. It ranged from 19 to 99 years, with a mode of 70 years. The sex of 406 patients was known: 187 (46.1%) were women and 219 (53.9%) men. The most common diagnoses leadind to anticoagulant therapy were a mechanical valve replacement in 265 patients and atrial fibrillation in 123 patients. Of all the patients included in the study, 194 had some complication. At the moment of the complication, 152 (78.4%) patients were being treated with generic warfarin and 42 (21.6%) with Coumadin Of the 194 patients who had complications, 114 (58.76%) had some kind of bleeding episode. 7 patients had major bleeding, and 107 had a minor episode. Besides the bleeding there were other complications such as nausea, headaches, vomiting, diarrhea, and anaphylaxis. After the complication, 47 patients were switched from generic warfarin to Coumadin. An improvement was seen in 94.9%. 8 patients were switched from Coumadin to generic warfarin, and improvement was seen in only 12.5%. Conclusions: the frequency of minor bleeding episodes is significantly higher in patients treated with generic warfarin than in those treated with Coumadin. In patients who presented with complications and were switched from generic warfarin to Coumadin, a major improvement was observed. This finding was not observed in patients switched from Coumadin to generic warfarin (Acta Med Colomb 2010; 35: 175-178).