Interaction between warfarin and danshen (Salvia miltiorrhiza)

Area of Science:

• Pharmacology
• Herbal Medicine Interactions

Background:

• Danshen (Salvia miltiorrhiza) is a traditional Chinese herb used for cardiovascular and cerebrovascular diseases.
• It possesses multiple mechanisms affecting hemostasis, including platelet inhibition and fibrinolysis.

Purpose of the Study:

• To evaluate the potential adverse interaction between danshen and warfarin.
• To review existing literature and case reports on this interaction.

Main Methods:

• A comprehensive literature search was conducted using MEDLINE (1966-2000) with keywords 'danshen' and 'Salvia miltiorrhiza'.
• Studies on danshen's antithrombotic effects and its interaction with warfarin were assessed.
• Published case reports of adverse events were reviewed.

Main Results:

• Danshen significantly alters warfarin's pharmacokinetics and pharmacodynamics in rats, increasing its absorption and half-life while decreasing clearance.
• This leads to exaggerated anticoagulant responses to warfarin.
• Three case reports document severe overanticoagulation and bleeding in patients concurrently using danshen and warfarin.

Conclusions:

• Pharmacokinetic and pharmacodynamic interactions between danshen and warfarin can result in dangerous overanticoagulation.
• Danshen should be contraindicated in patients undergoing warfarin therapy to prevent adverse events.