What is known about the interaction of ubidecarenone (coenzyme Q10) and warfarin?

Fråga: What is known about the interaction of ubidecarenone (coenzyme Q10) and warfarin?

Sammanfattning: Ubidecarenone has been reported to cause a decrease in INR value in warfarin treated patients, although this appears not to occur in all patients. As the clinical benefit of ubidecarenone is unproven, the use of this substance in warfarin treated patients cannot be recommended.

Svar: Ubidecarenone is an enzyme involved in mitochondrial electron transfer and the synthesis of adenosine triphosphate (ATP). It has structural similarities with vitamin K (1). In Sweden it is classified as a dietary supplement and the maximal recommended daily dose is 30 mg (2). In patients with heart failure, doses of 100 mg/d have been given in clinical trials (1).

There are six published case reports of changed INR values in warfarin treated patients, who have started taking ubidecarenone. In five of these, the INR value have decreased, and in the sixth INR increased (3,4,5,6).

A 68-year-old man on warfarin therapy had a decrease in his INR from 2.6 to 1.3 two weeks after he had started taking ubidecarenone (30,mg/d). After withdrawal of ubidecarenone his INR value stabilised. Low INR values (1.5 and 1.3) were noted at two occasions in a 72-year-old man. He had taken ubidecarenone at both of these occasions. His INR had fluctuated before, although it had not been below 2.0 at any time during the last nine weeks. A decrease in INR from 2.8 to 1.4 was observed in a woman two weeks after she had started taking ubidecarenone (30mg/d) (3). In a 72-year-old woman INR decreased from a stable value between 2-3 to 1.0 after she had started taking ubidecarenone. After withdrawal of ubidecarenone her INR increased to therapeutic level and remained stable (4). INR fell in a 61-year-old man on warfarin therapy after he started taking ubidecarenone. INR returned to therapeutic level one week after he had stopped taking ubidecarenone (5). In a woman treated with ubidecarenone (30 mg/d), for warfarin induced hair loss, the INR value initially increased and then slowly returned to the pervious level (6).

No interaction between warfarin and ubidecarenone was observed in a double blind, randomised, placebo controlled crossover study involving 24 patients. Ubidecarenone (100 mg/d) was given for four weeks to warfarin treated patients. INR was measured each week and the warfarin dose adjusted if INR was below 2 or above 4. The INR values remained stable during the treatment period and the average dose of warfarin was not changed (7).