Fish oil interaction with warfarin

[Guest guest]

Hi All,

 

See abstract, below. It suggests that fish oil may provide additive

anticoagulant effects when given with warfarin.

 

Best regards,

Phil

 

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

 

Fish oil interaction with warfarin. Buckley, MS; Goff, AD; Knapp,

WE Annals of Pharmacotherapy (USA) VOL. 38 NO. 1, 2004, 50-

53. Shawnee Mission Med Ctr, Shawnee Mission, KS, USA

OBJECTIVE: To report a case of elevated international normalized

ratio (INR) in a patient taking fish oil and warfarin. CASE

SUMMARY: A 67-year-old white woman had been taking warfarin

for 1 1/2 years due to recurrent transient ischemic attacks. Her

medical history included hypothyroidism, hyperlipidemia,

osteopenia, hypertension, and coronary artery disease. She also

experienced an inferior myocardial infarction in 1995 requiring

angioplasty, surgical repair of her femoral artery in 1995, and hernia

repair in 1996. This patient has her INR checked in the

anticoagulation clinic and is followed monthly by the clinical

pharmacist. Prior to the

interaction, her INR was therapeutic for 5 months while she was taking warfarin

1.5 mg/d. The patient admitted to doubling her fish oil dose from 1000 to 2000

mg/d. Without dietary, lifestyle, or medication changes, the INR increased from

2.8 to 4.3 within 1 month. The INR decreased to 1.6 one week after subsequent

fish oil reduction, necessitating a return to the original warfarin dosing

regimen.

DISCUSSION: Fish oil supplementation could have provided additional

anticoagulation with warfarin therapy Fish oil, an omega-3 polyunsaturated fatty

acid, consists of eicosapentaenoic acid and docosahexaenoic acid. This fatty

acid may affect platelet aggregation and/or vitamin K-dependent coagulation

factors. Omega-3 fatty acids may lower thromboxane A<INF>2</INF> supplies

within the platelet as well as decrease factor VII levels. Although

controversial,

this case report illustrates that fish oil can provide additive anticoagulant

effects

when given with warfarin. CONCLUSIONS: This case reveals a significant rise in

INR after the dose of concomitant fish oil was doubled. Patients undergoing

anticoagulation therapy with warfarin should be educated about and monitored

for possible drug-herb interactions. Pharmacists can play a crucial role in

identifying possible drug interactions by asking patients taking warfarin about

herbal and other alternative medicine product use.

 

 

Best regards,

 

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