Time-contingent schedules for postoperative analgesia: a review of the literature.

The management of pain reflects a history of myths and misconceptions often based on the "common sense" of the time. Evidence-based approaches to patient care are now strongly advocated. Recognizing that the accepted practice for administering postoperative analgesics has become the time-contingent or around-the-clock (ATC) regime, this article reviews the existing literature in search of empirical evidence supporting this practice. The review was conducted through MEDLINE, with the database limited to articles in the English language, involving human subjects, and published between 1960 and 2000. Database searches included each of the terms schedule, ATC, time, regime, administration, hour, dosing, qid, q6h, q4h, pro re nata, regular, and prn. Furthermore, common pain relieving drugs used in the postoperative period also were used as search words. Every database search was qualified by the terms post-operative or postoperative. The search showed sparse empirical work warranting endorsement of this dosing regimen. Although a great deal is known about specific drugs and dosage requirements, research is needed that clearly examines optimal scheduling regimens if we are to maximize patient care.