Potentiation of vitamin K antagonists by high-dose intravenous methylprednisolone.
BACKGROUND
Oral anticoagulants and pulse high-dose intravenous methylprednisolone are often administered concomitantly, but no data on potential interactions are available.


OBJECTIVE
To assess possible potentiation of oral anticoagulation by high-dose intravenous methylprednisolone.


METHODS
Prospective cohort study.


METHODS
University hospital in Paris, France.


METHODS
10 consecutive patients concomitantly receiving methylprednisolone and oral anticoagulants (fluindione and acenocoumarol) and 5 consecutive controls receiving methylprednisolone alone.


METHODS
Serial determinations of the international normalized ratio (INR) and clotting factors during administration of pulse methylprednisolone. The total plasma fluindione concentration was determined in 3 patients.


RESULTS
The mean INR was 2.75 (range, 2.02 to 3.81) at baseline and increased to 8.04 (range, 5.32 to 20.0) after methylprednisolone administration. Plasma fluindione concentrations and the INR increased after methylprednisolone administration. Methylprednisolone alone did not increase prothrombin time.


CONCLUSIONS
The action of oral anticoagulants is potentiated by intravenous high-dose methylprednisolone. The INR should be monitored daily during concomitant administration of these medications.
Costedoat-Chalumeau
N
N
Groupe Hospitalier Universitaire Pitié-Salpêtrière, Paris, France.
Amoura
Z
Z
Aymard
G
G
Sevin
O
O
Wechsler
B
B
Cacoub
P
P
Du
L T
LT
Diquet
B
B
Ankri
A
A
Piette
J C
JC
D000074:Acenocoumarol / Q000008:administration & dosage*; D000328:Adult; D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage* / Q000097:blood; D001779:Blood Coagulation Factors / Q000378:metabolism; D004357:Drug Synergism; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D019934:International Normalized Ratio; D008297:Male; D008775:Methylprednisolone / Q000008:administration & dosage* / Q000494:pharmacology; D008875:Middle Aged; D010630:Phenindione / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood; D011446:Prospective Studies; D011486:Protein C / Q000378:metabolism; D017293:Protein S / Q000378:metabolism; D011517:Prothrombin Time; D014812:Vitamin K / Q000037:antagonists & inhibitors*
D000925:Anticoagulants; D001779:Blood Coagulation Factors; D011486:Protein C; D017293:Protein S; D014812:Vitamin K; D010630:Phenindione; C017673:fluindione; D000074:Acenocoumarol; D008775:Methylprednisolone