Anxiolytic medication as an adjunct to morphine analgesia for acute low back pain management in the emergency department: a prospective randomized trial.

STUDY DESIGN

Prospective, single-blinded, and randomized clinical trial.

OBJECTIVE

This study evaluates the added benefit of promethazine administration as an anxiolytic adjunct to morphine analgesia in reducing acute low back pain (LBP) compared with morphine alone.

SUMMARY OF BACKGROUND DATA

Acute LBP is one of the most common reasons for emergency department (ED) visits. The optimal analgesic treatment for acute LBP remains controversial. Anxiety relief has been shown to improve pain management in the ED setting. We hypothesized that administration of the antihistamine promethazine as an anxiolytic adjunct to morphine analgesia will improve LBP management compared with morphine alone.

METHODS

Fifty-nine adults, who were treated in our ED for severe acute LBP (visual analogue scale ≥ 70 mm), were randomly enrolled in the study. Thirty patients received slow infusion of intravenous (IV) morphine 0.1 mg/kg in normal saline and 29 patients received an analgesic regimen of IV morphine 0.1 mg/kg with promethazine 25 mg administered similarly. Pain and anxiety levels were subjectively assessed by the patients on a 100-mm visual analogue scale before and after treatment. Adverse event related to analgesia were recorded in real time.

RESULTS

After analgesia administration patients' pain rating decreased by 43 mm in the morphine group and by 39 mm in the morphine/promethazine group (P = 0.26). Similarly, patients' anxiety decreased by 19 mm in the morphine group and by 13 mm in the morphine/promethazine group (P = 0.37). The average ED stay was 78 minutes longer in the morphine/promethazine group (P = 0.01), due to the strong sedative effect of promethazine. Patients' satisfaction and the rate of adverse events were similar in both groups.

CONCLUSION

IV administration of morphine-promethazine regimen for pain and anxiety relief associated with acute LBP showed no advantage compared with IV morphine alone and significantly lengthened the overall ED stay. Thus, we think that promethazine has no place in acute LBP management in the adult ED setting.

LEVEL OF EVIDENCE