DOSE CHANGES IN LONG-TERM AND MEDIUM-TERM INTRATHECAL MORPHINE THERAPY OF CANCER PAIN

INTRATHECAL MORPHINE ANALGESIA for the treatment of cancer pain was administered using implanted ports and drug delivery systems (DDS) in 79 patients. Effective control of the pain was achieved in nearly all patients; in only two patients was the use of the DDS discarded because of relative ineffectiveness. Fifty-three manual drug release systems (41 lumbar, 12 ventricular) and 26 lumbar ports were used. Forty patients survived more than 2 months; the maximum survival time was 560 days (mean survival time, 80 days with a port system, 100 days with a manual DDS). Patients still alive at the time of this study, i.e., with unknown survival time, were excluded. The initial mean daily dose was 8.5 mg in lumbar ports, 2.75 mg in lumbar DDS, and 0.2 mg with intraventricular application. Dose change patterns disclosed no alteration of the initial dose in 18 of 26 port patients, an initial increase in 4, a preterminal increase in 3, and a single intermittent increase in 1 patient. Of 40 lumbar DDS patients, 13 showed a constant dose, 9 an initial, 3 a preterminal, and 5 an intermittent increase. Three patients with less than 2 months' survival time had a rather continuous increase. All long-time survivors (i.e., with more than 2 months' survival time) reached a plateau and remained there until a preterminal if any increase occurred. These findings suggest the morphine dosage to be indicative of the progress of the disease rather than of a drug tolerance. In 12 patients with intraventricular medication, 5 remained stable with a dose between 0.3 and 0.9 mg, and 7 showed a continuous increase to between 1 and 6 mg, the causative mechanisms being unclear. Opiate dependence was never observed as a result of the spinal treatment. Observed side effects included nausea, vomiting, urinary retention, and obstipation; respiratory depression judged by clinical observation only was never observed. These results show that cancer pain can be controlled by intrathecal morphine and that the necessary dose increases were not frequent and were well tolerated and nearly always controlled the patients' pain adequately.