Intravenous morphine for rapid control of severe cancer pain

This randomized controlled trial compared intravenous route with oral route for initial dose titration of morphine in 62 patients with end-stage cancer and severe pain. Patients in the intravenous group received 1.5 mg intravenous bolus doses of morphine every ten minutes till pain relief was total or until they became drowsy. After that they got oral morphine at a dose equal to the total initial intravenous requirement four-hourly. Patients in the oral group got oral morphine 5 mg doses (if opioid-naïve) or 10 mg (if already on weak opioid) four-hourly. Patients in both groups had the option to receive rescue doses of their regular oral dose as and when needed, if necessary hourly. Twenty-seven of 31 in the intravenous group had either total or satisfactory pain relief by the end of one hour, whereas only eight of 31 in the oral group had a similar result. After 24 hours and later both groups had similar results. There was no immediate serious side effect in any of the patients. The late side effects were similar in the two groups. In the intravenous group, the ratio of initial intravenous dose requirement to the subsequent regular single oral dose after two days centred around 1:1 (range 1:0.5-1:3.3). This study found the intravenous method to be safe, effective and superior to the traditional method in providing immediate relief to severe cancer pain.