Effect Of Low-dose Naloxone On The Analgesic Efficacy Of Morphine And The Level Of Plasma Opiate-like Substance In Cancer Patients With Intractable Pain

Objective:To evaluate the effect of low-dose naloxone on the analgesic efficacy of morphine and the level of plasma opiate-like substance(OLS) in cancer patients with intractable pain receiving patient-controlled intravenous analgesia(PCIA) with morphine.Methods:Sixty cancer patients with intractable pain receiving PCIA with morphine were randomly divided into 3 groups:group M(10μg/kg/h morphine were added in PCIA pump),group MN0.05(10μg/kg/h morphine and 0.05μg/kg/h naloxone were added in PCIA pump),and group MN0.2(10μg/kg/h morphine and 0.2μg/kg/h naloxone were added in PCIA pump).5μg/kg morphine were set as bolus.The analgesic efficacy was observed, including VAS,volume of morphine use,and the adverse reaction of morphin. And the level of plasma OLS,includingβ-endorphin(β-EP),dynorphin Al-13(DynAl-13),and leu-enkaphalin(L-EK),was determined.Results:Compared with group M,the VAS scores were significantly lower in group MN0.05 and significantly higher in group MN0.2(P＜0.05). Compared with group M and group MN0.2,the volume of morphine use in group MN0.05 were significantly lower(P＜0.05).The volume of morphine use were comparable in group M and group MN0.2.Compared with group M,The incidence of adverse reaction of morphin were comparable in group M0.05 and group MN0.2,and both of them were significantly higher compared with groupM. The Compare with group M,in group MN0.05,the plasma levels of DynAl-13 and L-EK OLS were significantly higher at every observation,and the plasma level ofβ-EP was significantly lower after 1 day,but comparable at other time(P＜0.05).No significant difference in the plasma level of OLS was found between group M and group MN0.2.Conclusion:Different doses of naloxone have different effects on the analgesic efficacy of morphine in caner patients with intractable pain, which may act by affecting the synthesis and secretion of OLS.