Investigation Into the Therapeutic Dosage of Fondaparinux Sodium, a Medication Used to Prevent Blood Clots in Morbidly Obese Volunteers

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00436787
Recruitment Status : Completed
First Posted : February 19, 2007
Last Update Posted : May 16, 2008
Information provided by:
University of Pittsburgh

Brief Summary:
Morbidly obese individuals are at high risk for potentially life threatening blood clots around the time of abdominal surgical procedures. Fondaparinux sodium (Arixtra) is an FDA- approved medication used in the prevention of deep venous thrombosis (DVT) at the time of orthopedic or abdominal surgery, as well as for the treatment of DVT and pulmonary embolism (PE). As with many medications, therapeutic dosages have not been fully investigated for the morbidly obese population. Our goal is to study the therapeutic blood levels, after 2 different dosages of the medication are given to morbidly obese volunteers. We will recruit 21 morbidly obese (Body Mass Index (BMI) > 35) individuals who are in the evaluation process for bariatric surgery. They will be divided into 7 groups: 3 participants with BMI 35 - 39.9, 3 with a BMI of 40 - 49.9, 3 with a BMI of 50 - 59.9, 3 with a BMI > 60, 3 with a weight of 100 - 149 KG, 3 with a weight of 150 - 199 KG and 3 with a weight of 200 - 249 KG. Participants will be administered two different doses of the medication with a 2-week interval in between, then blood will be drawn in various intervals throughout the next 48 hours to see which dose provides the best therapeutic levels. Participants will be monitored closely for any side effects or complications.

Condition or disease Intervention/treatment Phase
Venous Thrombosis Pulmonary Embolism Drug: Fondaparinux Sodium Phase 2

Expanded Access : University of Pittsburgh has indicated that access to an investigational treatment associated with this study is available outside the clinical trial.  

Detailed Description:

Bariatric surgery carries a mortality rate of 0.5-1%, with PE found to be the most frequent postoperative complications and causes of death. Currently employed prophylactic methods include unfractionated or low molecular weight heparins in combination with mechanical calf compression. However, despite the implementation of these standard measures, the reported incidence of fatal PE has ranged from 0.2 to 0.64% accounting for between 30 to 50% of deaths after bariatric surgery.

With a reported 40,000 bariatric surgical procedures in 2001, and the numbers growing rapidly every year, there is clearly a need for a more effective prophylaxis from DVT and PE. The pentasaccharide fondaparinux is an anti-thrombotic agent used in the prophylaxis of venous thromboembolism after orthopedic or abdominal surgery. Its clinical value has been established in multiple randomized double blind studies in high-risk major orthopedic surgery where it showed a 55% greater reduction in DVT episodes compared to enoxaparin (Lovenox®) Although fondaparinux has been administered in obese patients in clinical studies for prevention of venous thromboembolism after orthopedic surgery and preliminary results show no influence of ABW on the clinical outcome, the pharmacokinetic properties of the drug in the morbidly obese have not been investigated. Previously published fondaparinux pharmacokinetic studies excluded patients whose body weight was more than 30% of ideal, with the heaviest group being 77.2+/-10.1 Kg and with a BMI of 25.7+/2.6 Kg/m2. Similar studies on low molecular weight heparins, such as enoxaparin and dalteparin, showed predictable anti-Xa activity with weight-based dosing in the morbidly obese.

There has been no study on the pharmacokinetics of this drug in the morbidly obese (BMI>35 Kg/m2). It is clinically imperative to have a predictable anti-Xa level and a predictable DVT prophylactic effect in the morbidly obese whose body weight may vary by as much as 3 to 4 fold higher compared to the average 70 Kg adult. This has become a critical issue in view of the large number of bariatric surgical operations being undertaken, which has increased 150% in the last two years.

The purpose of this study is to assess the pharmacokinetic properties of fondaparinux in morbidly obese volunteers. This is a prospective crossover, randomized study with a 2-week washout period comparing two dosing regimens of fondaparinux in morbidly obese volunteers.

Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 21 participants
Allocation: Non-Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)
Primary Purpose: Prevention
Official Title: Pharmacokinetic Properties of Fondaparinux Sodium in Morbidly Obese Volunteers
Study Start Date : February 2007
Actual Study Completion Date : December 2007

Resource links provided by the National Library of Medicine

Primary Outcome Measures :
  1. The pharmacokinetic properties of fondaparinux sodium in morbidly obese individuals.

Secondary Outcome Measures :
  1. Comparisons of the pharmacokinetic parameters of morbidly obese participants receiving 2.5 mg or 5 mg dose of fondaparinux sodium with those of healthy normal-weight volunteers established from previous studies.
  2. Comparison of the pharmacokinetic parameters of the 2.5 mg and 5 mg dosage of fondaparinux sodium.
  3. Evaluate the effect of BMI and ABW on the pharmacokinetic parameters of the 2.5 mg and 5 mg dosages of fondaparinux sodium.
  4. Assess the safety of fondaparinux sodium, as measured by defined safety endpoints, and compare the 2 dose groups for differences in the incidence of adverse events (AE).

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Ages Eligible for Study:   18 Years to 65 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No


  1. Age 19-65 years
  2. BMI 35-65 Kg/m2
  3. Pregnancy test Negative on day of study
  4. Past DVT/PE/MI These patients will not be excluded providing they are not on current therapy with anticoagulants, aspirin, or anti-platelet agents.


  1. BP ≥ 160/90
  2. Temperature > 37.5 0C (99.5 0F)
  3. Nursing mothers Exclude if nursing
  4. Pregnancy test Positive on day of study
  5. Medications Anticoagulants, anti-platelet agents, aspirin, NSAIDs within a month of the study

Past medical history

  1. cerebrovascular accident (including TIA within 6 months of the study)
  2. Diabetic retinopathy proven by fundoscopy
  3. History of inherited thrombotic/hypercoagulable defect
  4. Active peptic ulcer disease diagnosed by upper endoscopy
  5. Known bleeding disorder, thrombophilia
  6. History of heparin induced thrombocytopenia
  7. History of bacterial endocarditis
  8. Known hypersensitivity to fondaparinux
  9. Ulcerative colitis
  10. History of GI bleeding
  11. History of hematuria
  12. Recent surgery (last 3 months)
  13. Recent trauma (last 3 months)

Laboratory values

  1. Platelet count ≤ 100,000 mm3
  2. Hemoglobin < 12 g/dL (women), or < 14 g/dL (men)
  3. Prothrombin time > 13 sec
  4. PTT > 35 sec
  5. ALT 3xULN and bilirubin 1.5xULN (>35% direct); or ALT 5xULN; or ALT 3xULN if associated with the appearance or worsening of hepatitis symptoms or rash
  6. Estimated urinary creatinine clearance ≤ 50 ml/min
  7. Hematuria on urine dipstick

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00436787

United States, Pennsylvania
Magee Women's Hospital
Pittsburgh, Pennsylvania, United States, 15213
Shadyside Medical Building
Pittsburgh, Pennsylvania, United States, 15232
Sponsors and Collaborators
University of Pittsburgh
Principal Investigator: Ioannis Raftopoulos, MD, PhD University of Pittsburgh Identifier: NCT00436787     History of Changes
Other Study ID Numbers: ART108029
First Posted: February 19, 2007    Key Record Dates
Last Update Posted: May 16, 2008
Last Verified: May 2008

Keywords provided by University of Pittsburgh:
Anticoagulation Prophylaxis
Venous Thrombosis
Deep Vein Thrombosis
Pulmonary Embolism
Fondaparinux Sodium

Additional relevant MeSH terms:
Pulmonary Embolism
Venous Thrombosis
Embolism and Thrombosis
Vascular Diseases
Cardiovascular Diseases
Lung Diseases
Respiratory Tract Diseases
Factor Xa Inhibitors
Serine Proteinase Inhibitors
Protease Inhibitors
Enzyme Inhibitors
Molecular Mechanisms of Pharmacological Action
Fibrinolytic Agents
Fibrin Modulating Agents