Capsules and suppositories of methadone for patients on high-dose opioids for cancer pain: clinical and economic considerations.

The dose ratio, analgesic efficacy, toxicity and cost of methadone for cancer pain were evaluated in a retrospective review of 50 consecutive patients treated on a Palliative Care Unit. Patients were switched from hydromorphone 267.7 +/- 178.8 mg sc per day to custom-made capsules (24) or suppositories (26) of methadone for reasons of uncontrolled pain (24), toxicity (8), both (15) or other (2). The change in opioid occurred over 2.5 +/- 3.6 days, with another 4.4 +/- 3.7 days required to reach stable methadone dose. The ratio of stable methadone dose to final hydromorphone dose was 1.07 +/- 0.9 (oral) and 1.88 +/- 1.27 (rectal) (p = 0.01). Visual analogue scores for pain intensity (0-100 mm) declined from 50.8 +/- 22 to 40 +/- 20 (p = 0.01). The most frequent toxicities were constipation (46), sedation (42) and nausea (18). Six patients developed respiratory depression. Total cost of treatment was Canadian $116.77 +/- 157.17 for methadone capsules and Canadian $105.34 +/- 146.35 for methadone suppositories, vs Canadian $3450.51 +/- 5098.58 (p = 0.0001) for hydromorphone parenteral solution and Canadian $1801.21 +/- 2661.52 (p = 0.0001) for hydromorphone powder. It is concluded that methadone is an effective and inexpensive alternative in patients receiving high-dose opioids for cancer pain, at dose ratios much lower than recommended in the literature. The incidence of serious toxicities suggests that methadone should only be initiated in an adequately monitored setting by pain management experts.