Miconazole Vaginal Cream and Suppositories
Safety Information
Science Background: Safety of Miconazole Vaginal
Cream and Suppositories. February 28, 2001
This summary is to inform health care professionals that women who take a warfarin
anticoagulant and use a miconazole intravaginal cream or suppository may be at risk for
developing an increased prothrombin time, international normalized ratio (INR) and
bleeding. Vaginal antifungal products containing miconazole will shortly have a new
warning to advise consumers about the possibility of increased bleeding or bruising with
concomitant warfarin use.
History
Miconazole is an imidazole antifungal drug that has been available by prescription and
over-the-counter in different formulations for many years. The adverse interaction of
systemically administered miconazole with warfarin is well established. Several recent
adverse event reports and literature reports have noted a prolongation of INR and
prothrombin time in patients taking warfarin who use miconazole vaginal preparations.
Reports
The FDA has received two adverse event reports of women who concomitantly took
anticoagulant therapy and used vaginal miconazole for three days. Both of them increased
their INR. One woman taking acenocoumarol used miconazole vaginal cream for an
indeterminate length of time and developed an increased prothrombin time. One woman who
took warfarin and inserted vaginal miconazole for 2 days, in addition to increasing her
prothrombin time, developed bruises, gingival bleeding and a nosebleed.
Two articles in the medical literature report cases of a probable warfarin interaction
with vaginal miconazole. 1,2
Discussion
These reports suggest that there is a probable interaction between warfarin
anticoagulants and intravaginal miconazole. It is important for physicians and patients to
understand that this interaction may occur with these topical miconazole products so that
patients who need to use both products simultaneously will be appropriately monitored. The
new warning will state "Ask a doctor or pharmacist before use if you are
taking the prescription blood thinning medicine warfarin, because bleeding or bruising
may occur."
Outcome
The FDA is notifying all manufacturers of over-the-counter miconazole vaginal cream
and/or vaginal suppositories to place a new warning (see above) on the product
labels. This warning informs consumers who take the prescription blood thinning agent
warfarin that they should consult their doctor or pharmacist for advice before
using the intravaginal product. Sponsors of these products will be asked to provide
information on this interaction to health care professionals through their marketing
representatives.
___________________________________
1 Thirion DJ, Zanetti LA. Potentiation
of Warfarin’s Hypoprothrombinemic Effect with Miconazole Vaginal Suppositories.
Pharmacotherapy 2000;20(1):98-99.
2 Lansdorp D, Bressers HP, Dekens-Konter JA, Meyboom RH. Potentiation of
Acenocoumarol During Vaginal Administration of Miconazole. Br J Clin Pharmacol
1999;47:225-6.
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Last Updated: March 08, 2001
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