help with consistent PRN med charting

I am a senior nursing student. We are beginning our CQI project on PRN monitoring. On the advice of the clinical educator on the med/surg floor I am presently working at she recommended this as a huge problem. The nurses either don't chart the PRN given, opr forget to chart on the MAR the effects of the PRN. To chart the effects you must turn the MAR to the back.. THis is where the problem is..the nurses forget to do this. I was just wondering if there are any different ways or new ways you may do PRN meds. We are trying to change this to make it more consistent and effective. If you have any suggestions at all it will be appreciated. This project is due in a couple of weeks and I could really use some user friendly advice.
thanks