Self-administration of morphine in bone marrow transplant patients reduces drug requirement

Bone marrow transplant recipients were randomly assigned to receive morphine by either continuous infusion (32 patients) or self-administration of small boluses (patient-controlled analgesia (PCA), 26 patients) for control of chemoradiotherapy-induced oral mucositis pain. All patients received morphine for a minimum of 9 days and most required morphine for at least 14 days. Patients rated their pain and side-effect intensity daily using visual analogue scales. Patient pain ratings did not differ between the groups although PCA patients used only 53% as much morphine as the continuous infusion group. Tolerance did not develop in the PCA group; in patients receiving continuous infusion morphine dosage continued to increase throughout the study while pain scores remained constant, indicating that tolerance had developed. Nausea, alertness and respiratory rate measurements did not differ between groups. PCA appeared more effective than the hospital staff determined treatment at delivering the least amount of morphine required to produce maximal pain relief. Patients self-administering morphine did not appear to restrict morphine intake in order to minimize opioid side-effects.