Superior Efficacy of IV Morphine + Oxycodone Combination in Patients with Moderate-to-Severe Pain Following Total Hip Replacement

AUSTIN, TX—The use of intravenous morphine + oxycodone had superior efficacy when compared with morphine alone, according to results presented at the American Pain Society's 30th Annual Scientific Meeting.

This randomized, double-blind trial of 40 patients compared IV morphine alone vs. a combination of morphine + oxycodone in a 1:1 ratio. The goal of the study's authors, Patricia Richards, MD, PhD, and colleagues of QRxPharma, Bedminster, NJ, was to show superior efficacy or safety of the combination at equivalent doses. Patients underwent total hip replacement and, following surgery, when their pain levels reached 4 on a 0–10 scale, they were randomized to one of the two treatment groups. For Part 1 of the study, patients were administered an initial loading dose, then either 1.5mg morphine or 0.75mg morphine/0.75mg oxycodone every 5 minutes for the first 65 minutes, up to 13 doses. They were continued on this as long as they met vital signs criteria. If patients achieved a pain score of 2 or were intolerant to the drug when stable, they were permitted to enter Part 2, the PCA period, where they received blinded study medication for an additional 47 hours.

Results from the study demonstrated baseline pain intensity averaging 7 on the 0–10 Numerical Pain Rating Scale (NPRS). During the titration period, efficacy measured using median SPID65 min was 1.8 for morphine alone vs. 2.7 for morphine + oxycodone combination (50% increase in the pain relief for the combination) despite the same median number of doses administered (n=12) for each group. A total of 67% of patients receiving IV morphine + oxycodone reported good to excellent global improvement (ie, experienced good to very good pain relief) compared with 53% of those receiving IV morphine alone.

Adverse event (AE) profiles showed 24% of the combination group and 37% of the morphine group had nausea. Similarly, 10% of the combination group vs. 16% of the morphine group had emesis. Oxygen desaturation was observed by 10% of patients in the morphine + oxycodone group compared with 16% of the morphine group who experienced this AE.

Dr. Richards concluded that morphine + oxycodone combination had superior efficacy vs. morphine alone with a better gastrointestinal AE profile.