You took emergency contraception
due to condom failure.
Emergency contraception Plan B
consist of levenorgesteral.
is usually know to cause drug interactions with most of the drugs.
Regarding interaction with Plan B there is no solid evidence of decreased in effectiveness.
But definetely it wont cancel the effect of your Plan B.
Get a consultation with your Gync or cautiously wait.
You should always inform your doctor about your medications in future.