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Completed

NCT Number: NCT02780622

A Pharmacokinetics, Pharmacodynamics and Safety Study of Warfarin in Combination With Tamiflu (Oseltamivir)

This is an open-label, randomized, 2-period crossover study, to evaluate the pharmacokinetics, pharmacodynamics, safety and tolerability of warfarin in combination with Tamiflu (oseltamivir) in participants stabilized on warfarin. Participants will be randomized to receive either their warfarin followed oseltamivir and warfarin, or by oseltamivir and warfarin followed by warfarin. The treatment periods will be separated by a washout period of at least 4 days. Participants will continue receiving warfarin once daily at a prescribed usual dose throughout the study.

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Key information

Conditions

Drug Therapy, Combination

Age range

18 year–75 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 4

Primary location

Surrey, CR7 7YE, United Kingdom

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Participants must have been receiving warfarin once daily for at least 4 weeks prior to Screening
  • Participants must have regular International Normalized ratio (INR) monitoring during warfarin therapy prior to study entry, and be willing to be trained in the use of CoaguCheck devices
  • INR must fall within a target range of 2.0-3.5
  • Body mass index (BMI) between 18-32 kg/m^2 inclusive

Exclusion criteria

  • An INR value between screening and Day -1 lower than 2.0 or greater than 3.5
  • A change in prescribed daily warfarin dose between Screening and Day -1
  • History of any coagulopathy
  • Consumption of health products or supplements containing vitamin K
  • Pregnant or lactating women
  • Confirmed positive urine and/or blood test for drugs of abuse at Screening or Day -1

Treatment and study plan

oseltamivir

Drug

Oseltamivir 75 mg orally, twice daily for 4 days and once on Day 5.

Other names: Tamiflu®

Warfarin

Drug

Warfarin once daily, at a dose determined through titration by participants' usual hematologist.

Primary outcomes

  1. Area Under the Plasma Effect-time Curve Over 96 Hours (AUEC[0-96 h]) for International Normalized Ratio (INR)

    Time frame: Pre-dose on Day 1, 24 hours (Day 2), 48 hours (Day 3), 72 hours (Day 4), and 96 hours (Day 5)

    INR is calculated based on results of a prothrombin time (PT) test (which measures how long it takes blood to clot) and is used to monitor individuals who are being treated with the blood-thinning medication (anticoagulant) warfarin. The net AUEC(0-96 h) was calculated using the linear trapezoidal rule; this was the area under the effect-time curve and above the baseline minus the area above the curve and below the baseline during the 5-day period. An increase in INR signifies enhancement of warfarin's anticoagulant effect.

  2. Change From Baseline in Maximum Observed Effect (Emax) of International Normalized Ratio (INR)

    Time frame: Pre-dose on Day 1, 24 hours (Day 2), 48 hours (Day 3), 72 hours (Day 4), and 96 hours (Day 5)

    INR is calculated based on results of a prothrombin time (PT) test (which measures how long it takes blood to clot) and is used to monitor individuals who are being treated with the blood-thinning medication (anticoagulant) warfarin. An increase in INR signifies enhancement of warfarin's anticoagulant effect.

  3. Time to Reach Maximum Change From Baseline in International Normalized Ratio (INR) (Tmax)

    Time frame: Pre-dose on Day 1, 24 hours (Day 2), 48 hours (Day 3), 72 hours (Day 4), and 96 hours (Day 5)

    INR is calculated based on results of a prothrombin time (PT) test (which measures how long it takes blood to clot) and is used to monitor individuals who are being treated with the blood-thinning medication (anticoagulant) warfarin. An increase in INR signifies enhancement of warfarin's anticoagulant effect.

  4. Area Under the Plasma Effect-time Curve Over 96 Hours (AUEC[0-96 h]) for Factor VII Activity

    Time frame: Pre-dose on Day 1, 24 hours (Day 2), 48 hours (Day 3), 72 hours (Day 4), and 96 hours (Day 5)

    Factor VIIa is a protein that causes blood to clot, and low levels in the blood can cause excessive or prolonged bleeding after an injury or surgery. The net AUEC(0-96 h) was calculated using the linear trapezoidal rule; this was the area under the effect-time curve and above the baseline minus the area above the curve and below the baseline during the 5-day period. A decrease in factor VIIa activity signifies enhancement of warfarin's anticoagulant effect. kIU/L = 1000 * international units per liter.

  5. Change From Baseline in Maximum Observed Effect (Emax) in Factor VII Activity

    Time frame: Pre-dose on Day 1, 24 hours (Day 2), 48 hours (Day 3), 72 hours (Day 4), and 96 hours (Day 5)

    Factor VIIa is a protein that causes blood to clot. A decrease in factor VIIa activity signifies enhancement of warfarin's anticoagulant effect. kIU/L = 1000 * international units per liter.

  6. Time to Reach Maximum Change From Baseline in Factor VII Activity (Tmax)

    Time frame: Pre-dose on Day 1, 24 hours (Day 2), 48 hours (Day 3), 72 hours (Day 4), and 96 hours (Day 5)

    Factor VIIa is a protein that causes blood to clot. A decrease in factor VIIa activity signifies enhancement of warfarin's anticoagulant effect.

  7. Change From Baseline in Plasma Concentration of Vitamin K1

    Time frame: Pre-dose on Day 1 and 24 hours post-dose on Day 5

    Vitamin K1 is required by proteins involved in blood clotting. Food interaction with warfarin can lead to decreases in Vitamin K1 in plasma. An increase in vitamin K1 signifies enhancement of warfarin's anticoagulant effect.

Secondary outcomes

  1. Time to Maximum Plasma Concentration (Tmax) for Oseltamivir and Oseltamivir Carboxylate

    Time frame: Pre-dose; 0.5, 1, 1.5, 2, 3, 4, 6, 8, 10 and 12 hours post-dose on Day 1 and 5; 18 and 24 hours post-dose on Day 5

    Oseltamivir carboxylate is an active metabolite of oseltamivir.

  2. Time to Maximum Plasma Concentration (Tmax) for R- and S- Warfarin

    Time frame: Pre-dose; 1, 2, 4, 8, 12, 24 hours post-dose on Day 5

  3. Terminal Half-life (t½) for Oseltamivir and Oseltamivir Carboxylate

    Time frame: Pre-dose; 0.5, 1, 1.5, 2, 3, 4, 6, 8, 10 and 12 hours post-dose on Day 1 and 5; 18 and 24 hours post-dose on Day 5

    Oseltamivir carboxylate is an active metabolite of oseltamivir.

  4. Terminal Half-life (t½) for R- and S- Warfarin

    Time frame: Pre-dose; 1, 2, 4, 8, 12, 24 hours post-dose on Day 5

  5. Oral Plasma Clearance (CL/F) for Oseltamivir

    Time frame: Pre-dose; 0.5, 1, 1.5, 2, 3, 4, 6, 8, 10 and 12 hours post-dose on Day 1 and 5; 18 and 24 hours post-dose on Day 5

  6. Oral Plasma Clearance (CL/F) for R- and S- Warfarin

    Time frame: Pre-dose; 1, 2, 4, 8, 12, 24 hours post-dose on Day 5

  7. Maximum Plasma Concentration (Cmax) for Oseltamivir and Oseltamivir Carboxylate

    Time frame: Pre-dose; 0.5, 1, 1.5, 2, 3, 4, 6, 8, 10 and 12 hours post-dose on Day 1 and 5; 18 and 24 hours post-dose on Day 5

  8. Maximum Plasma Concentration (Cmax) for R- and S- Warfarin

    Time frame: Pre-dose; 1, 2, 4, 8, 12, 24 hours post-dose on Day 5

    R- and S-warfarin are two molecular versions of warfarin with slightly different structures. The reported concentrations were normalized by dividing the Cmax values (nanograms per milliliter) by the individual average dose (milligrams).

  9. Area Under the Plasma Concentration-time Curve Over the Time Interval From Zero to 24 Hours (AUC0-24h) for Oseltamivir and Oseltamivir Carboxylate

    Time frame: Pre-dose; 0.5, 1, 1.5, 2, 3, 4, 6, 8, 10, 12, 18 and 24 hours post-dose on Day 5

  10. Area Under the Plasma Concentration-time Curve Over the Time Interval From Zero to 24 Hours (AUC0-24h) for R- and S- Warfarin

    Time frame: Pre-dose; 1, 2, 4, 8, 12, 24 hours post-dose on Day 5

    R- and S-warfarin are two molecular versions of warfarin with slightly different structures. The reported concentrations were normalized by dividing the AUC values (hours multiplied by nanograms, per milliliter) by the individual average dose (milligrams).

  11. Area Under the Plasma Concentration-time Curve Over the Time Interval From Zero to 12 Hours (AUC0-12h) for Oseltamivir and Oseltamivir Carboxylate

    Time frame: Pre-dose; 0.5, 1, 1.5, 2, 3, 4, 6, 8, 10 and 12 hours post-dose on Day 1 and 5; 18 and 24 hours post-dose on Day 5

  12. Area Under the Plasma Concentration-time Curve Over the Time Interval From Zero to 12 Hours (AUC0-12h) for R- and S- Warfarin

    Time frame: Pre-dose; 1, 2, 4, 8, 12, 24 hours post-dose on Day 5

    R- and S-warfarin are two molecular versions of warfarin with slightly different structures. The reported concentrations were normalized by dividing the AUC values (hours multiplied by nanograms, per milliliter) by the individual average dose (milligrams).

  13. Percentage of Participants With Adverse Events

    Time frame: Up to Day 26

    An adverse event was defined as any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product.

Sponsors and collaborators

Lead sponsor

Hoffmann-La Roche

Industry

Registry information

Official study title

An Open-label, Randomized 2-period Crossover Study to Investigate the Pharmacodynamics, Pharmacokinetics, Safety and Tolerability of Warfarin in Combination With Oseltamivir in Volunteers Stabilized on Warfarin Therapy

Important dates

Study start
2008
Primary completion
2008
Study completion
2008
First posted
May 23, 2016
Registry last updated
Oct 26, 2016

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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