Benefits of Adding Low-Dose Ketamine to Morphine for Severe Renal Colic Pain

Low-dose ketamine is coming into wide use as an analgesic in the emergency department setting. Investigators in Iran randomized 106 patients with severe renal colic pain to receive morphine (0.1 mg/kg) plus either low-dose ketamine (0.15 mg/kg) or placebo. Outcomes included pain rated on a 10-point visual analog scale at 10, 30, 60, 90, and 120 minutes, and number of additional doses of morphine given.

At baseline, the average pain score was 7.9 points in both groups. At 120 minutes, the average pain score was <1 point in both groups. However, at 10 and 30 minutes, the ketamine group had a significantly lower average pain score than the placebo group (4.6 vs. 6.0 at 10 minutes; 3.7 vs. 4.8 at 30 minutes) and required significantly fewer addi…