Ive just started taking slow release propranalol for ectopic/irregular heartbeats and must say I feel like a different person. Im sleeping at night, feel like doing stuff, not lethargic. HOWEVER my thyroxine is interfering with my propranalol i am sure. Last week as an experiment i didnt take any thyroxine and had hardly any ectopics or thudding heart. On the advice of a stand in doc this week i restarted my thyroxine and am now back to having the flutters, ectopics and thumping heartbeats. I managed to speak to my own GP today and she is e mailing the endocronologist at the hospital for advice. At my wits end! Has anyone else had reactions with thyroxine and other drugs?