How Long Does Metoprolol Succinate Take To Show Effect?

HOW LONG DOES METOPROLOL ER SUCCINATE 100 MG take TO WORK ON A MAN 235 POUNDS AND 6 FEET TALL/ muscular BUILD. HE WAS TAKING 50 MG FOR A WEEK AND IT DID NOT WORK SO DOCTOR UPPED DOSAGE TO 100 MG yesterday. HE HAS TAKEN TWO DOSAGES OF 100 MG yesterday and today. THIS MED IS FOR FAST HEART BEAT PROBLEM OF ABOUT 125 BEATS, HE ALSO PUT HIM ON LISINOPRIL 20 MG AND XARELTO 20 MG FOR AFIB. Has been taking Xarelto 20 for a week. His blood pressure is fine but his heart is still beating too fast.