Anticoagulant activity of coumarin

Hypoprothrombinemia may occur in malabsorption syndromes and also the use of broad-spectrum antibiotics may produce a hypoprothrombinemia that responds readily to small doses of vitamin K. In premature infants and in infants with hemorrhagic disease of the newborn the use of vitamin K may be indicated. However, the main indication for the use of vitamin K is to antagonize the anticoagulant activity of coumarins. Oral absorption of phytonadione and the menaquinones is by the lymph while menadione and its water-soluble derivatives are absorbed directly. The absorption of phytonadione is energy-dependent and saturable. Intravenous administration of phytonadione has produced flushing, dyspnea, chest pains, and cardiovascular collapse. 

Lamnaouer, D. (1999). Anticoagulant activity of coumarins from Ferula communis L (review). Therapie54(6) 747-51. (In French)... 

There are no studies of the effect of clarithromycin on the pharmacokinetics or anticoagulant activity of coumarins. However, there are at least 13 cases of increased INRs in published reports, and one cohort study suggesting that the use of clarithromycin is associated with an increased risk of bleeding in patients taking coumarins. These are discussed below. 

Rosselli S, Maggio A, Bellone G, Formisano C, Basile A, Cicala C, Alfieri A, Mascolo N, Bruno M (2007) Antibacterial and anticoagulant activities of coumarins isolated from the flowers of Magydaris tomentosa. Planta Med 73 116... 

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See also in sourсe #XX -- [ , , , , , , , , , ]

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