Does flutamide ( antiandrogen) interact with synthroid (thyroxine)?

No it doesn't: But your medication list notes both synthroid (with is a quality brand-name levothyroxine) as well as levothyroxine. Hopefully, you're not taking both. The brand name synthroid is the better product of the two.

A valuable resource: You can use a drug interaction checker whenever you have questions about drug-drug interactions or drug - food interactions. Here is one option (Drugs.Com): https://www.drugs.com/drug_interactions.php Your pharmacist is also an excellent source of information.