My patient has a prescription for temazepam 15mg. The prescription says "PO HS PRN MR x 1 for sleep". What the heck is MR? I understand the rest...by mouth at bedtime as needed times 1, but the MR has got me confused. All of the abbreviation websites I have gone to suggest things that are obviously wrong: mental retardation, medical record, etc. Does anyone know what this means? It's driving me crazy!