RESUMO
Objective: To investigate the efficacy of patients with cancer-induced bone pain (CIBP) treated with morphine in combination with dexamethasone through intrathecal pumping injection and its mechanism. Methods: Seventy-six patients with CIBP undergoing implantation of an infusion port with intrathecal catheter were randomly divided into group A (n = 38, intrathecally injected with morphine alone and group B (n = 38, intrathecally injected with morphine in combination with dexamethasone). The pain relief degree by 11-Point Numeric Rating Scale (NRS-11) score, the frequency of breakthrough pain, quality of life and SF-36 scale score were evaluated before treatment and the 1st, 3rd and 7th days after the beginning of intrathecal pumping. On the 7th day after treatment, the concentrations of â-endorphin (â-EP) and motilin in plasma as well as prostaglandin E2 (PGE2), substance P (SP) and calcitonin gene-related peptide (CGRP) in cerebrospinal fluid (CSF) were determined. Results: The pain was relieved significanly in group B, and the frequencies of breakthrough pain per day were less than those in group A on the 1st, 3rd and 7th days after treatment (all P 0.05); in group B, the SF-36 scale score and quality of life were both improved significantly on the 3rd and 7th days after treatment as compared with those of group A (all P 0.05), but the motilin level in plasma in group B was significantly higher than that in group A (P < 0.05); the PGE2, SP and CGRP levels in CSF in group B were significantly lower than those in group A (all P < 0.05). Conclusion: Intrathecal pumping injection of morphine in combination with dexamethasone can be of great help in decreasing the frequency of breakthrough of CIBP, improving the quality of life, and increasing the motilin level in plasma, but decreasing PGE2, SP and CGRP levels in CSF which may contribute to alleviating the tolerance of morphine, thus enhance the analgesic effect.