Hi My Dad Is Taking Selomax 25/2.5 .. He Is

hi
my dad is taking selomax 25/2.5 .. he is perfectly alright but when he monitors his pulse rate it goes down in the evening / night... the pulse rate without taking medicine is around 60 - 65 but it goes down to 43 - 45
can you please help if it is concern or it is alright. He does not face any problem..he is normal but when his pulse rate is high around 80 and above he feels severe anxiety and uneasiness