Effect of intravenous administration of paracetamol on morphine consumption in cancer pain control

The present study aimed to examine the effectiveness of intravenous administration of paracetamol added to morphine in the control of cancer pain and its possible contribution as reduction of opioid consumption and opioid-related side effects. A total of 43 patients with chronic cancer pain without neuropathic origin aged between 18 and 76 years and receiving step 2 treatment according to the World Health Organization analgesic ladder were included. Patients were randomized to receive intravenous administration of saline (control) or 1 g of paracetamol on top of morphine. Visual analog scale (VAS), patient rating index (PRI), Eastern Cooperative Oncology Group (ECOG) status, patient satisfaction, and safety were evaluated. Both treatments resulted in improved VAS and PRI scores compared to baseline. However, groups did not differ in terms of VAS and PRI scores, morphine consumption, side-effect frequencies, laboratory values, ECOG status, and patient satisfaction. Although safe and there are signals for a true analgesic efficacy, our results failed to confirm any benefits of add-on treatment with intravenous administration of paracetamol. However, the study was underpowered, and future studies in this important area need to be wary of background noise and the risk of a type II error.