Tier 3 — preclinical

Effect of Coenzyme Q10 and Ginkgo biloba on warfarin dosage in patients on long-term warfarin treatment. A randomized, double-blind, placebo-controlled cross-over trial

Jytte Engelsen, Jørn Dalsgaard Nielsen, Kaj Flemming Winther Hansen
Ugeskrift for Laeger 2003 165(18):1868-1871

Bibliography

PubMed
PMID 12772396
Funding
Funding information was not identified in the accessible indexed record.
Competing interests
Competing-interest information was not identified in the accessible indexed record.

Study snapshot

DesignRandomized, double-blind, placebo-controlled crossover trial
ModelOutpatients on stable long-term warfarin therapy
Sample24 enrolled; 21 completed
InterventionCoQ10 100 mg/day, Ginkgo biloba 100 mg/day and placebo in random crossover order; each treatment period lasted four weeks with two-week washouts
DurationThree 4-week treatment periods with 2-week washouts
EndpointsInternational normalized ratio (INR); Weekly warfarin dose required to maintain INR 2.0–4.0

What the study showed, in plain terms

Twenty-four patients on stable long-term warfarin therapy entered a randomized double-blind crossover trial comparing CoQ10 100 mg/day, Ginkgo biloba and placebo; 21 completed the study.

INR remained stable and the average weekly warfarin dose required during the CoQ10 period did not differ meaningfully from placebo. This controlled trial therefore did not demonstrate a clinically important interaction at 100 mg/day over four weeks.

The study is reassuring but too small and short to rule out uncommon interactions, effects from other doses or formulations, or changes when CoQ10 is started or stopped outside closely monitored anticoagulation care.

Key findings

INR remained stable across CoQ10, Ginkgo and placebo periods.

Geometric mean weekly warfarin dose was 36.5 mg during CoQ10 versus 36.0 mg during placebo, with overlapping confidence intervals.

The controlled trial did not confirm the reduction in warfarin effect suggested by earlier case reports.

What this study can and cannot tell us

Small sample: 24 enrolled and 21 completed.

Only four weeks of CoQ10 exposure at 100 mg/day, so uncommon events, higher doses and different formulations were not tested.

Warfarin dose was adjusted to maintain INR, which reflects monitored clinical care but can mask a subtle interaction that is compensated by dose adjustment.

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Dr. Khaled Mahmoud, MBBChCritical Care Medicine, Longevity Science & Editorial Direction Dr. Amr Yasser, PhDCardiometabolic, Musculoskeletal, Gut & Bioavailability Dr. Abdulla Mostafa, PhDCellular Senescence, Neurological, Mitochondrial & Brain-Ageing Biology