Z.A.
Check with your pharmacist. (Actual pharmacist, not just a tech...sorry any techs out there, I'm sure you know a heck of a lot more then I do!) Pharmacists not only spend years in school learning about drugs and their interactions etc. but they keep up on all the new ones. In FACT there are countless times where Pharmacists have saved lives because someone's doc prescribed a med that would be dangerous to that individual (usually because of drug interactions, but also for other reasons).
If your med ISN'T safe for breast feeding have the pharmacist write a note to your doc. They'll probably put down some safe alternatives.