Around-the-clock (ATC) dosing of analgesics.

TWO BASIC PRINCIPLES of providing effective pain management are preventing pain and maintaining a pain rating that allows the patient to accomplish functional or quality-of-life goals with relative ease. These may require that the mainstay analgesic be administered on a scheduled around-the-clock (ATC) basis, rather than ‘‘as needed’’ (PRN) to maintain stable analgesic blood levels. ATC dosing regimens are designed to control baseline pain, defined as the pain the patient reports as being the average pain intensity experienced for 12 hours or more during a 24-hour period. In other words, ATC dosing should be used when pain itself is ATC (continuous) or present for 12 or more hours each day. Many types of persistent (chronic) cancer and noncancer pain are continuous, and most postoperative pain is continuous for at least the first 24 hours after surgery.