Is there a risk of an interaction if an Echinacea remedy is administered concurrently with warfarin

Fråga: Is there a risk of an interaction if an Echinacea remedy is administered concurrently with warfarin?<br><br>A male patient was treated normal with Waran (warfarin) before a planned cardio version. After four months of treatment with INR values of in average 3.0 the patients INR suddenly increased to 5.7. INR was normalised within a week. Later the patient told the physician that he had self-medicated with Echinagard for a cold at the same time period as the sudden increase in INR. The patient is also treated with sotalol. The case has been reported to the regional adverse drug reaction registry.

Sammanfattning: No information about drug interactions between warfarin and Echinacea remedies was found in the literature. One case report of unusual blood loss during surgery in a patient who took Echinacea only has been published in the literature. Based on these data it is not possible to conclude whether or not there is a risk.

Svar: Echinagard drops contain the juice of Echinacea purpura. The indication approved for this herbal remedy is common cold. Questions concerning interactions between Echinacea remedies and warfarin have previously been answered in Drugline; no information of a possible drug interaction was found (1,2).<br><br>Nor could an updated literature search in Medline, Embase, Micromedex and other available pharmacological sources revealed any such information. However, one case report of a 60-year-old woman, not treated with warfarin, who suffered from unusual blood loss (500ml) during a lumpectomy of the breast, was found (3). Vital signs, as well as coagulation studies were normal, except for slightly elevated thrombin time. Preoperative questions revealed that she had taken Echinacea remedies during three weeks for a cold. She had no other medication.<div id="referenser" style="display:none;">1 Drugline no 12604 (year 1995)<br>2 Drugline no 12197 (year 1995)<br>3 Ananthanarayan C, Urbach G. Herbals - beware bleedint. Correspondence. Can J Anesth 200;47:1046-8.</div>