Dextropropoxyphene versus morphine in opioid-naive cancer patients with pain.

The role of opioids for moderate pain (so-called "weak" opioids) in the second step of the World Health Organization's analgesic ladder has been investigated in a prospective randomized study. Sixteen patients were administered dextropropoxyphene (DPP) in a dosage ranging from 120 mg to 240 mg daily (group 1), and 16 patients were administered the lowest doses (20 mg daily) of commercially available controlled-release morphine (group 2). Equianalgesic doses of oral morphine, pain relief, and symptoms during the first 10 days of therapy and during the last 4 weeks before death were assessed. Three of 16 patients maintained DPP until death, whereas three patients in group 2 were switched to DPP due to the occurrence of intolerable side effects. Intensity and frequency of nausea and vomiting, drowsiness, and dry mouth were higher in group 2 than in group 1 during the initial treatment. These results stress the role of "weak" opioids during the induction of opioid therapy in opioid-naive cancer patients.