My 89 year old mother experienced some TIAs in late July. She has been taking the following meds since then, along with previous prescriptions. 75 mg Clopiogrel, 80 mg Atorvastatin, 1/4 of 25 mg tab, twice a day Metoprolol tartrate, 10 mg Lisinopril. Previously prescribed: 25 mg Levothyroxine and 10mg Melatonin for sleep. Is there a substitute for the metoprolol?