Postoperative pain control by transdermal fentanyl. Preliminary comparison of two dosages to a fixed-interval i.m. morphine regimen.

The efficacy of postoperative pain control with two doses of transdermal fentanyl were compared to a fixed-interval intramuscular (i.m.) morphine regimen in 21 patients undergoing orthopedic surgical procedures. The two transdermal fentanyl patches with delivery rates of 70-80 micrograms/hr and 90-100 micrograms/hr, groups one and two, respectively, were compared to an i.m. morphine regimen of 150 micrograms/kg every 6h, group three. Transdermal patches were applied one hour prior to surgery and removed after 24h. Analgesia, safety scores, side effects, and a global postoperative evaluation were recorded by a blinded physician at frequent intervals up to 36h. No significant difference in pain intensity, evaluated by the visual analog scale, were found between the three groups. Group two had the lowest discomfort score. Groups one and two had a significantly lower respiratory rate than group three. Although there were isolated significant differences in peripheral hemoglobin saturations, these differences were not consistent. This is the first study in which transdermal fentanyl was compared to a fixed-interval i.m. morphine protocol without supplementation with other narcotics. The results show that fentanyl by a transdermal route can provide analgesia comparable to i.m. morphine. No clinically important adverse side effects were found in any of the study groups.