Clinical experience with oral methadone administration in the treatment of pain in 196 advanced cancer patients.

PURPOSE: The aims of this study were to describe the analgesia, side effects, and dosage and the causes of suspension of treatment in a large sample of advanced cancer patients with pain after treatment with oral methadone from 7 to 90 days. PATIENTS AND METHODS: In a retrospective study, data collected for 196 advanced cancer outpatients with moderate to severe pain treated at 8-hour intervals with oral methadone in solution form from February 1993 to February 1995 were analyzed at baseline (time 0) and then at 7, 15, 30, 45, 60, and 90 days. The following parameters were assessed: Karnofsky Performance Status, intensity of pain (using the Integrated Pain Score [IPS], intensity of pain, insomnia, drowsiness, confusion, dry mouth, nausea, vomiting, constipation, and dyspnea (using the Therapy Impact Questionnaire [TIQ], mean daily dose of drug administered, and reasons for withdrawal from study. The period when pain was reduced by > or = 35% with respect to baseline was evaluated with the Palliation Index. The association of the degree of palliation of pain with the age of the patients, tumor site, analgesic treatment taken at baseline, and daily mean dose of methadone administered during the follow-up period was analyzed by means of the Kruskal-Wallis test.
RESULTS: A reduction in pain intensity with respect to baseline occurred at each analysis time, and in 55.1% of the patients the reduction during the follow-up period was > or = 35% according to the Palliation Index. The mean dose of oral methadone ranged from 14 mg at day 7 to 23.65 mg at day 90. There was an overall worsening of the other symptoms, but a high percentage of the patients reported an amelioration of insomnia with respect to baseline. There was a statistically significant association (P < .0001) between the Palliation Index and the analgesic therapy administered at baseline. Only 11.2% of the patients withdrew from the study due to analgesic inefficacy and 6.6% due to methadone-related side effects (10 patients with drowsiness and three with severe constipation.
CONCLUSION: Oral methadone administered every 8 hours was shown to be an appropriate analgesic therapy in the treatment of advanced cancer-related pain. The worsening of the other symptoms under study can be considered linked to the progression of the disease, and in fact, only a small percentage of the patients reported methadone-related side effects that warranted suspension of treatment. We consider oral methadone to be a useful analgesic therapy, and it should be considered in clinical practice for the treatment of cancer pain.