Efficacy of Paracetamol in Addition to Morphine to Improve Analgesia in the Emergency Department

Paracetamol (acetaminophen) is widely used around the world for mild to moderate pain in all age groups. Prescription at the emergency department is very common and some studies suggest the use in alternative of Morphine, at least in the renal colic.

Morphine has also a complex analgesic effect due to inhibition of µ Receptors in the central nervous system and in the dorsal horn of the spinal cord. Morphine (like other opioids) is accepted as a cornerstone of acute pain management in the emergency department. However, occurrence of adverse drug reactions is up to 25%, mainly nausea and drowsiness.

The use of paracetamol in addition to morphine showed in a meta-analysis in the post-operative setting an opioid sparing effect of 20% over the first postoperative 24 hours, but did not change the incidence of morphine-related adverse effects in the postoperative period. An additive effect was showed of the two medicaments in another Study measuring the median effective analgesic dose (ED50).

The purpose of this study is to test the additional effect of paracetamol in combination with morphine for analgesia, respectively to test/confirm an opioid sparing effect due to the additional use of Paracetamol, as well as the to reduction of adverse drug reactions of morphine.

The study is a multicenter, randomized, double-blind, placebo-controlled. We randomize patients with pain-score >=4 on a pain Scala of 0-10 Points (numeric rating scale) in two group, one with paracetamol, one with placebo to investigate the (additive) effect of paracetamol in combination with morphine. The treatment team and the patients will be blinded to the administration. The study design is outlined to confirm the result of previous studies who stated a 20% reduction of morphine doses when combined with paracetamol. Study duration for each patient would be 240 min.

Inclusion criteria

• Patient with pain with Pain-score is more or equal than four in a numeric rating scale from zero to ten (i.e. indication for a treatment with morphine)
• Age over 18
• Signed informed consent. In case, patient is not able to sign the informed consent due to pain, at least verbal consent has to be provided. After pain relief, written informed consent with data and time has to be obtained

Exclusion criteria

• Analgesia in the past last 6 hours prior to visit at the emergency department
• Current Analgesia with long-acting/extended-release drugs
• Current Analgesia with opioids
• Chronic pain syndrome
• Contraindication for either paracetamol or morphine
• Patient's refusal of paracetamol or morphine treatment
• Pregnancy or Breastfeeding
• GCS < 13
• SpO2 < 90% with a maximum of 4 L/Min O2
• Systolic Blood Pressure < 90 mmHg
• "Fast Track"/Notfallpraxis patients