European Pharmacopoeia (Ph. Eur.) monograph 0828 prescribes two in vitro assays to evaluate the biological activity of low-molecular-mass heparin products. These assess the capacity of low-molecular-mass heparins to accelerate the inhibition of factor Xa and factor IIa by antithrombin. A reference standard calibrated in International Units (IU) such as the Heparin low-molecular-mass for assay Biological Reference Preparation (BRP), is required to express results. Due to low stocks, the Biological Standardisation Programme (BSP) of the Council of Europe and the European Union launched an international collaborative study to establish a replacement batch for the current Heparin low-molecular-mass BRP (BRP10). Thirteen Official Medicines Control Laboratories and manufacturers contributed data to calibrate a candidate batch against the World Health Organization (WHO) 3rd International Standard for Heparin, low molecular weight (11/176; 3rd IS) using chromogenic assays. The overall anti-Xa and IIa activities of the candidate BRP against the 3rd IS based on the participants\' calculations and on central calculation at the European Directorate for the Quality of Medicines & HealthCare (EDQM) were very close. The inter-laboratory variation for both assays was between 2.8 % and 7.5 %. The study data confirmed the assigned activities of BRP10. Based on the results of this collaborative study, in December 2019 the Ph. Eur. Commission adopted the candidate BRP as Heparin low-molecular-mass for assay BRP batch 11 with assigned anti-Xa activity of 110 IU/mL and anti-IIa activity of 37 IU/mL.

OBJECTIVE: To determine the thrombotic and hemorrhagic risk in bariatric surgery with multimodal rehabilitation programs, comparing two guidelines of pharmacological prophylaxis recommended in the Guide to the Spanish Society for Obesity Surgery and the Obesity Section of the AEC.
METHODS: Cohorts retrospective study from January-2010 to December-2019. Cases of vertical gastrectomy or gastric bypass were recorded, systematically applying multimodal rehabilitation protocols. Two reduced chemoprophylaxis regimens were analyzed, starting after surgery and maintained for 10 days; one with fondaparinux (Arixtra®) at a fixed dose of 2.5mg/day and the other with enoxaparin (Clexane®) with a single daily dose adjusted to BMI: 40mg/day for BMI of 35-40 and 60mg/day for BMI 40-60.
RESULTS: 675 patients were included; 354 with Fondaparinux-Arixtra® during the period 2010-2015 and 321 with Enoxaparin-Clexane® during the period 2016-2019. There were no cases of DVT or clinical PE. However, the incidence of hemorrhage requiring reoperation, transfusion, or a decrease of more than 3g/dL hemoglobin was 4.7%, with no difference between groups. Mortality was nil. The average stay was 2.8 days and the outpatient follow-up was 100% during the first 6 months and 95% at 12 months.
CONCLUSIONS: The combination of multimodal rehabilitation programs and mechanical and pharmacological thromboprophylaxis by experienced teams, reduces the risk of thromboembolic events and could justify reduced chemoprophylaxis regimens to decrease the risk of postoperative bleeding.

OBJECTIVE: to determine the thrombotic and hemorrhagic risk in bariatric surgery with multimodal rehabilitation programs, comparing 2guidelines of pharmacological prophylaxis recommended in the Guide to the Spanish Society for Obesity Surgery and the Obesity Section of the AEC.
METHODS: Cohorts retrospective study from January-2010 to December-2019. Cases of vertical gastrectomy or gastric bypass were recorded, systematically applying multimodal rehabilitation protocols. Two reduced chemoprophylaxis regimens were analyzed, starting after surgery and maintained for 10 days; one with fondaparinux (Arixtra®) at a fixed dose of 2.5mg / day and the other with enoxaparin (Clexane®) with a single daily dose adjusted to BMI: 40mg / day for BMI of 35-40 and 60mg/day for BMI 40-60.
RESULTS: 675 patients were included; 354 with Fondaparinux-Arixtra® during the period 2010-2015 and 321 with Enoxaparin-Clexane® during the period 2016-2019. There were no cases of DVT or clinical PE. However, the incidence of hemorrhage requiring reoperation, transfusion, or a decrease of more than 3g / dL hemoglobin was 4.7%, with no difference between groups. Mortality was nil. The average stay was 2.8 days and the outpatient follow-up was 100% during the first 6 months and 95% at 12 months.
CONCLUSIONS: The combination of multimodal rehabilitation programs and mechanical and pharmacological thromboprophylaxis by experienced teams, reduces the risk of thromboembolic events and could justify reduced chemoprophylaxis regimens to decrease the risk of postoperative bleeding.