PRN TID

Say a medication (in this case ativan, dose is 0.5mg) can be give TID PRN. How far apart should the doses be spaced?

Suppose the first dose is given and is minimally effective? How long should the nurse wait before re-dosing?

There is more to this scenario, the nurse did not attempt any other interventions (Roxanol was also available, for example for pain r/t a rectal tumor and prostate cancer) and the pt. also had orders to straight cath if there was no voiding within a specific time frame.

The nurse gave him a second dose a little over three hours later, which resulted in the pt. being "snowed" the rest of the shift. The on-coming nurse did straight cath for over 700ml...

All of this has prompted much debate regarding the ativan. While I think she should have done a more thorough assessment and attempted some other interventions first, the real debate has revolved around the timing of the ativan dosing.

What are the guidelines for PRN dosing? Can anyone help me find a resource for this?

Some are saying TID PRN is equivalent to q8hours PRN. Others disagree...

BTW...pt's anxiety is manifested by crying and repetitive behaviors...not dangerous, not disruptive to anyone around him.