Pulmonary Embolism Support Group
By far the most common form of pulmonary embolism is a thromboembolism, which occurs when a blood clot, generally a venous thrombus, becomes dislodged from its site of formation and embolizes to the arterial blood supply of one of the lungs. Symptoms may include difficulty breathing, pain during breathing, and more rarely circulatory instability and death.
http://www.drugs.com/npp/quinine.html
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That site has slightly confusing about quinine and warfarin:
Warfarin
"There is no report of an interaction occurring with coadministration of quinine and warfarin. "
Then this:
However, in healthy subjects, quinine (330 mg) administration prolonged the prothrombin time (form 5 to 11.8 seconds) 41 and reduced the prothrombin content in blood in a patient receiving dicumarol (not available in the US). 42 A similar interaction may be expected to occur with coadministration of quinine and warfarin."
I suspect this is something you'll want to research fully.
The site offers this:
Scientific Name(s): Cinchona succirubra Pav. ex Klotsch (red cinchona), C. calisya Wedd., and C. ledgeriana Moens ex Trim. (yellow cinchona). Family: Rubiaceae
Common Name(s): Red bark , Peruvian bark , Jesuit's bark , China bark , cinchona bark , quina-quina , fever tree
As always--- supplements are to be viewed just like drugs, esp. with warfarin.