Pharmacodynamics of low molecular weight heparin in patients undergoing bariatric surgery: A prospective, randomised study comparing two doses of parnaparin (BAFLUX STUDY)☆
Received 21 November 2008; received in revised form 30 April 2009; accepted 30 April 2009.
Abstract
Background
The optimal dose of low-molecular-weight-heparin (LMWH) to prevent venous thromboembolism (VTE) after bariatric surgery remains controversial.
Aim
The aim of this study was to evaluate the pharmacodynamic parameters of two doses of the LMWH parnaparin administered to patients undergoing bariatric surgery.
Methods
Patients were enrolled in a multicentre, open label, pilot study and were randomised to receive 4250 IU/day [n=36; 30 females; median age: 38 years (23-56); median BMI: 46.7 Kg/m2 (36.5-58.8)] or 6400 IU/day [n=30; 24 females; median age: 42 years (22-63); median BMI: 43.7 Kg/m2 (36.1-64.1)] of parnaparin s.c. for 7-11 days. The pharmacodynamic effects of parnaparin were analysed by measuring the anti Factor Xa activity on day 0 (12 hours after the first parnaparin injection), day 4 and day 6 after surgery (before and 4 hours after parnaparin administration).
Results
In 98.3% of patients receiving 4250 IU/day the peak anti-Xa levels were in the range of 0.1-0.4 IU/ml. Higher anti-Xa levels were observed in patients receiving 6400 IU/day: in 62.3% of these patients the peak anti-Xa levels were greater than 0.4 IU/ml. The anti-Xa levels measured 4 hours after injection on days 4 and 6 were not statistically correlated with BMI for either dose of-parnaparin (p=0.077 and p=0.401 for 4250 or 6400 IU/day, respectively).
Conclusion
The dose of 4250 IU/day seems adequate to achieve prophylactic anti-Xa levels in morbid obese patients undergoing bariatric surgery. Conversely, most of the patients receiving 6.400 IU/day show anti-Xa levels higher than the recommended prophylactic values.
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