Coumarin Plant Poisoning Medication

Updated: Mar 31, 2014
  • Author: Arasi Thangavelu, MD, FACEP, FAAEM; Chief Editor: Asim Tarabar, MD  more...
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Medication

Medication Summary

For severe or continued bleeding, only vitamin K-1 (phytonadione) (not any other vitamin K derivatives) can be used as an effective antidote. Usual dose is 5-10 mg administered PO/SC. Intravenous injections, even in emergencies, carry substantial risk of anaphylaxis (fatalities have been reported) — Black Box warnings. Intravenous vitamin K should be used very cautiously in emergent conditions, should be diluted, and should be infused very slowly. If immediate hemostatic effect is necessary, adequate concentrations of vitamin K-dependent coagulation factors can be restored by transfusion of fresh frozen plasma (10-20 mL/kg). Since reversal of anticoagulant by vitamin K-1 requires synthesis of fully carboxylated coagulation proteins, significant improvement in homeostasis does not occur for several hours; more than 24 hours may be needed for maximal effect.

Small ingestions of plant material (equivalent to 10-20 mg warfarin) do not cause serious intoxication in adults, yet repeated or long-term ingestion of even smaller amounts (equivalent to 2 mg/d warfarin) can produce significant anticoagulation.

Recommendations from the Seventh ACCP Conference on antithrombotic and thrombolytic therapy: [2]

  • In patients with mild to moderately elevated INRs without major bleeding, vitamin K, when given, should be administered orally rather that subcutaneously (Grade 1 A).
  • For the management of patients with a low risk of thromboembolism, warfarin therapy should be stopped approximately 4 days prior to surgery (Grade 2C).
  • For patients with a high risk of thromboembolism, warfarin therapy should be stopped approximately 4 days before surgery, to allow the INR to return to normal, and therapy with full-dose unfractionated heparin or full dose low-molecular-weight heparin should begin as the INR falls (Grade 2C).
  • In patients undergoing dental procedures, tranexamic acid mouthwash (Grade 2B) or epsilon amino caproic acid mouthwash should be used without interrupting anticoagulant therapy (Grade 2B) if there is concern for local bleeding.

Grading: Grade 1 recommendations are strong, and indicate that the benefits do, or do not, outweigh the risks, burdens, and costs. Grade 2 suggest that individual patient's values may lead to different choices.

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GI decontaminants

Class Summary

Preferred GI decontamination method when decontamination is desired. Generally mixed and given with a cathartic (eg, 70% sorbitol) except in young pediatric patients in whom electrolyte disturbances may be of concern.

Activated charcoal (Liqui-Char)

Emergency treatment in poisoning caused by drugs and chemicals. Network of pores present in activated charcoal adsorbs 100-1000 mg of drug per gram of charcoal. Does not dissolve in water.

For maximum effect, administer within 30 min after ingesting poison.

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Elimination enhancement

Class Summary

Cholestyramine forms a nonabsorbable complex with bile acids in the intestine that inhibits enterohepatic reuptake of intestinal bile salts. Rifampin is used to speed up metabolism of warfarin by induction of hepatic cytochrome P-450 mixed function oxidases.

Cholestyramine (Questran)

Binds bile salts carrying warfarin and its metabolites, thus interfering with enterohepatic recycling.

Rifampin (Rifadin, Rimactane)

Hepatic P-450 enzyme inducer that results in increased metabolism of warfarin and decreased drug half-life.

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Pharmacologic antidote

Class Summary

Promotes liver synthesis of clotting factors that, in turn, inhibit warfarin effects.

Vitamin K-1 (Phytonadione, AquaMEPHYTON)

Overcomes block produced by hydroxycoumarin in production of vitamin K dependent clotting factors; vitamin K-3 (menadione) is not effective for this purpose.

Dose needed varies with clinical situation, including amount of anticoagulant ingested and whether it is a short- or long-acting anticoagulant. Daily doses of 50-200 mg have been required.

Use extreme caution if considering IV administration. Complications of IV use include flushing, diaphoresis, hypotension, dyspnea, and anaphylactoid reactions. SC is preferable to IV administration, which carries a strong box warning against IV administration by the manufacturer. In the patient on chronic anticoagulation for medical reasons, reversal should be performed only very carefully if clinically indicated. Re-anticoagulation can be very difficult in this situation.

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