Has there been reported any drug interactions between warfarin and Echinagard, Kan Jang or Lyprinol

Fråga: Has there been reported any drug interactions between warfarin and Echinagard, Kan Jang or Lyprinol?

Sammanfattning: There are a few case reports of possible drug interactions between warfarin and Echinagard and/or Kan Jang. No such reports were found for Lyprinol. However, omega-3 polysaturated fatty acids, which are included in Lyprinol, are known to increase the risk of bleeding. Based on these data, it is not possible to conclude whether the combination of warfarin with these natural remedies constitutes a clinically important risk. Patients treated with warfarin should be advised not to use natural remedies, based on the lack of documentation concerning their effects, as well as the contents of the remedies. If warfarin is used concomitantly with a natural remedy, a more careful monitoring of the coagulation status is recommended.

Svar: Drug interactions between natural remedies and warfarin are, in general, poorly studied. Therefore, it´s often hard to predict whether natural remedies can give rise to clinically important drug interactions. Some of the natural remedies that are available in Sweden have been regulated by the medical product agency regarding the contents. However, there are several natural remedies on the market where the contents have not been defined.<br><br>Echinagard is a natural remedy that contains the juice of Echinacea purpura and is approved for the treatment of common cold (1). There are only two case reports of concomitant use of warfarin and Echinacea remedies available (1, 2). In one case an increased INR value was observed, and in the other a decreased INR value. Both cases were assessed as possible side effects. One case of unusual blood loss during surgery in a patient that took Echinacea has also been published (1).<br><br>Kan Jang is a natural remedy that often contains extracts from Adhatoda vasica and Acanthopanax senticosus, as well as Echinacea purpura. The indication approved for this natural remedy is common cold (3). Three case reports of concomitant use of warfarin and Kan Jang are documented in the literature. One of these patients also took Echinagard and is the same patient as is mentioned above, with a decreased INR value. A decreased INR value was also observed in the second patient, judged as possibly related to the combination of warfarin and Kan Jang. In the third patient, nausea, dark coloured vomiting and faeces were reported, which later was diagnosed as prepyrolal bleeding without any certain ulceration, possibly related to the use of warfarin and Kan Jang (2).<br><br>Lyprinol is a dietary supplement and contains a mixture of different lipids, such as triglycerides, free fatty acids, sterols and polar lipids. Several of these lipids are of marine origin, and some are omega-3 polyunsaturated fatty acids, that are known to be able to increase the risk of bleeding by prolonged bleeding time and reduced thrombocyte aggregation (4, 5).<div id="referenser" style="display:none;">1 Drugline no 19482 (year 2002)<br>2 Swedis (The Swedish Drug Information System) (cited 2003-03-27)<br>3 Färnlöf Å, Tunon H. Naturläkemedel 2002/2003. Stockholm: Hälsokostrådets Förlag; 2002. p. 126-7.<br>4 About Lyprinol. http://www.lyprinol.com/structure.htm (cited 2003-03-20)<br>5 Drugline no 15608 (year 1998)</div>