Background: Combined analgesic regimens have been suggested to improve the treatment of postoperative pain. The aim of our study was to evaluate the analgesic efficacy and tolerability of propacetamol, in combination with morphine.
Methods: Four i.v. infusions of propacetamol 2 g or placebo were administered, in a double-blind fashion, after orthopedic surgery (n=97). Morphine was administered by a patient-controlled analgesia (PCA) device. The total dose of morphine, pain intensity and global efficacy of treatment were evaluated. Tolerability was assessed by monitoring blood pressure, heart and respiratory rate, sedation scores, adverse events, and renal and hepatic parameters.
Results: The total dose of morphine was significantly decreased in the propacetamol group compared to placebo (9.4±8.5 mg vs 17.6±12 mg; P< 0.001), arriving at a sparing effect of 46%. The evolution of pain intensity showed a similar pattern in the two groups. Global efficacy of treatment was rated significantly better by patients receiving the combination propacetamol+ PCA morphine (87% of “good”/“excellent” ratings vs 65%; P=0.01). Tolerability was comparable in the two groups. Eight patients in the propacetamol and 4 patients in the placebo group reported adverse events, of mild/moderate intensity, most commonly nausea/vomiting. Renal and hepatic parameters were also seen to be comparable.
Conclusions: These results confirm a significant morphine-sparing effect, significantly better scores in the final assessment by patients, and a good tolerability of propacetamol after orthopedic surgery. The drug may, therefore, represent a useful alternative to NSAIDs, as complementary drug to opioids, in the management of moderate/severe postoperative pain.