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Tenofovir Abacavir Platelet Activation Study (TAPAS)

This study is ongoing, but not recruiting participants.
Information provided by (Responsible Party):
Jan Gerstoft, Rigshospitalet, Denmark Identifier:
First received: March 18, 2014
Last updated: December 11, 2015
Last verified: December 2015
Some but not all observational studies have found that current exposure to abacavir is associated with increased risk of cardiovascular events such as myocardial infarction, stroke and cardiovascular death. This study aim to investigate possible adverse effect of abacavir on platelet reactivity, coagulation and endothelial activation in HIV-1 infected patients. The study is an open-labeled cross-over trial, where patients receiving antiretroviral therapy containing abacavir switch treatment to a regimen containing tenofovir and vice versa for a period of 90 days.

Condition Intervention Phase
Drug: abacavir (600 mg QD)
Drug: tenofovir (245 mg QD)
Phase 4

Study Type: Interventional
Study Design: Allocation: Non-Randomized
Intervention Model: Crossover Assignment
Masking: Open Label
Official Title: Changes in Coagulation and Platelet Reactivity in HIV-1 Infected Patients Switching Between Abacavir and Tenofovir Containing Antiretroviral Regimens

Resource links provided by NLM:

Further study details as provided by Rigshospitalet, Denmark:

Primary Outcome Measures:
  • Differences in platelet aggregation (Multiplate) before and after switching between abacavir and tenofovir. [ Time Frame: before and after 90 days intervention ] [ Designated as safety issue: No ]
  • Differences in clot formation kinetics (thromboelastography) before and after switching between abacavir and tenofovir. [ Time Frame: before and after 90 days intervention ] [ Designated as safety issue: No ]

Secondary Outcome Measures:
  • Concentration of plasma lipids [ Time Frame: Before and after 90 days intervention ] [ Designated as safety issue: No ]
  • activated partial thromboplastin time (APTT) [ Time Frame: 90 days ] [ Designated as safety issue: No ]
  • international normalized ratio (INR)/Factor II, VII, X [ Time Frame: Before and after 90 days intervention ] [ Designated as safety issue: No ]
  • Platelet count [ Time Frame: Before and after 90 days intervention ] [ Designated as safety issue: No ]
  • Fibrinogen [ Time Frame: Before and after 90 days intervention ] [ Designated as safety issue: No ]
  • D-dimer [ Time Frame: Before and after 90 days intervention ] [ Designated as safety issue: No ]
  • Antithrombine [ Time Frame: Before and after 90 days intervention ] [ Designated as safety issue: No ]
  • Interleukin 6 (IL-6) [ Time Frame: Before and after 90 days intervention ] [ Designated as safety issue: No ]
  • High sensitivity C reactive protein (HS-CRP) [ Time Frame: Before and after 90 days intervention ] [ Designated as safety issue: No ]
  • Soluble P-Selectin [ Time Frame: Before and after 90 days intervention ] [ Designated as safety issue: No ]
  • soluble CD40 ligand (sCD40L) [ Time Frame: Before and after 90 days intervention ] [ Designated as safety issue: No ]
  • Syndecan-1 [ Time Frame: Before and after 90 days intervention ] [ Designated as safety issue: No ]
  • Soluble E-selectin [ Time Frame: Before and after 90 days intervention ] [ Designated as safety issue: No ]
  • Tissue plasminogen activator [ Time Frame: Before and after 90 days intervention ] [ Designated as safety issue: No ]

Estimated Enrollment: 100
Study Start Date: January 2014
Estimated Study Completion Date: June 2016
Estimated Primary Completion Date: April 2016 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Tenofovir to abacavir
Patients switching from tenofovir (245 mg QD) to abacavir (600 mg QD)
Drug: abacavir (600 mg QD)
Experimental: Abacavir to tenofovir
Patients switching from abacavir (600 mg QD) to tenofovir (245 mg QD)
Drug: tenofovir (245 mg QD)


Ages Eligible for Study:   35 Years to 70 Years   (Adult, Senior)
Genders Eligible for Study:   Male
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • HIV-1 infected
  • Can understand and sign written informed consent
  • Received one of the above mentioned antiretroviral regimens continuously ≥ 6 months
  • HIV RNA < 400 copies/mL for ≥ 6 months

Exclusion Criteria:

  • Receiving anticoagulant therapy, adenosine diphosphate (ADP) receptor inhibitors, aspirin or nonsteroidal antiinflammatory drugs (NSAIDs)
  • Previous ischemic heart disease, peripheral atherosclerotic disease or stroke
  • Coagulation disorder (e.g. hemophilia, factor V Leiden mutation)
  • Platelet count < 150 x 109/L during the past 6 months from inclusion
  • Estimated glomerular filtration rate (eGFR) <70 during the past 6 months from inclusion
  • Humane leukocyte antigen (HLA)-B*57:01 positive genotype
  • Hepatitis B or C positive during the past year from inclusion
  • Hypersensitivity to the active substances or to any of the excipients
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT02093585

Rigshospitalet, Klinik for Infektionsmedicin og Reumatologi, 8622
Copenhagen Ø, Copenhagen, Denmark, 2100
Sponsors and Collaborators
Jan Gerstoft
Principal Investigator: Jan Gerstoft, MD, DMSc Rigshospitalet, Denmark
  More Information

Responsible Party: Jan Gerstoft, MD, DMSc, Professor, Rigshospitalet, Denmark Identifier: NCT02093585     History of Changes
Other Study ID Numbers: 2013-001685-42 
Study First Received: March 18, 2014
Last Updated: December 11, 2015
Health Authority: Denmark: Danish Dataprotection Agency
Denmark: Danish Health and Medicines Authority
Denmark: The Regional Committee on Biomedical Research Ethics
Denmark: National Board of Health

Keywords provided by Rigshospitalet, Denmark:
Platelet activation

Additional relevant MeSH terms:
Antiviral Agents
Anti-Infective Agents
Reverse Transcriptase Inhibitors
Nucleic Acid Synthesis Inhibitors
Enzyme Inhibitors
Molecular Mechanisms of Pharmacological Action
Anti-Retroviral Agents
Anti-HIV Agents
Antimetabolites processed this record on January 18, 2017