I just started as a nurse on a medical floor, I was on orientation. I had a coreg to give and the heart rate was 52, there was no parameters entered by the physician so I went ahead and gave it. Unknown to me, my preceptor came up to me later and said I wasn't suppose to give that because his heart rate was too low. No one told me on the floor that 60 was their magical number that was too low to give for coreg. (I still have to look up their policy and procedure) I was taught in nursing school that if its below 50 the general rule is to hold it if there is no parameter on it. I looked it up in my Davids drug book and it says the same thing, to hold it if its under 50. Consequently I was fired this past Monday due to this error. What is everyone's thoughts?