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HIV and Emerging Infectious Diseases Program

P-3 Study

Study Name

The Influence of Cobicistat or Ritonavir on Dabigatran Pharmacokinetics and Pharmacodynamics in Healthy Volunteers

Study Number


Goal of Study

People infected with the human immunodeficiency virus (HIV) often take a combination of anti-HIV (antiretroviral) medications to control their disease. For a variety of reasons, people living with HIV may also need to take medications to prevent blood clots. These medications that prevent blood clots are called anticoagulants. It is important to understand how antiretrovirals and anticoagulants interact with each other so that people taking these drugs together can be treated safely.

One such anticoagulant is dabigatran (Pradaxa). Some drugs used to treat HIV may increase the amount of dabigatran in the body when they are taken at the same time. This could lead to bleeding or other problems. However, this interaction may not happen if the drugs are given a couple of hours apart instead of at the same time.

In this study, we want to learn whether ritonavir (Norvir) will increase dabigatran blood levels. Ritonavir is an HIV medicine that is commonly used to increase the blood levels of other antiretrovirals so that they work better. We will recruit 16 people for this arm of the study.

After completion of the first 16 subjects, an additional 16 subjects will be recruited to take dabigatran with cobicistat (also an HIV medication.) Those volunteers who successfully completed the ritonavir portion of the study may also be considered to participate in the second arm of the study, if they wish. Participants must provide their own transportation to the NIH. Volunteers will be compensated.

Study Regimen

We will recruit 16 subjects who are HIV-negative, healthy individuals between 18 and 70 years of age. Volunteers must be in good general health, and be willing to take the medications dabigatran (Pradaxa, an anti-coagulant) and ritonavir, an HIV medication. The second group of 16 must be willing to take dabigatran with cobicistat, also an HIV medication. Each arm of the study requires seven visits in approximately a 54-day period. Four of those visits will last approximately one hour; three of those visits will last approximately 12 hours. Participants must provide their own transportation to the NIH.

Eligibility Criteria

  • You are age 18-70 years old, HIV-negative, and in good general health.
  • You are willing to take the study medications described above.
  • If you are female, you are not pregnant or breast feeding, and you agree to avoid pregnancy during the study.
  • You do not take any prescription medications or over-the-counter medications.
  • You have no history of a serious bleeding event.
  • Your cholesterol and blood sugar are normal.
  • You do not smoke.
  • You do not abuse drugs or alcohol.

Last Updated July 03, 2013