CHUMPITAZ-CORREDOR, D.    LARA-SOLARES, A.. Correlation between opioid dose and time response to methylnaltrexone. []. , 19, 1, pp.11-17. ISSN 1134-8046.

Introduction: the opioid bowell disfunction (OBD) has a prevalence among 20 and 80%, There for the use of prophylactic laxatives is an important resource. Approximately 80% of cancer patients will require laxatives. Opioids act on neuron's receptor in the enteric system, which leads to constipation by decreased peristalsis and secretions. Methylnaltrexone (MTNX) antagonized this effect. Objective: report the effect of MTNX administration (12 mg) subcutaneous via (SC) to reduce opioid-induced constipation. Material and methods: a retrospective, observational study during June 2009 - April 2010. Upon approval by the ethics committee of the institution included patients with OIC and received MTNX (12 mg SC) in one or more doses. We analyzed the following variables: age, diagnosis, opioid received (dose equivalent to PO mg of morphine for 24 hours), frequency of constipation, laxatives, additional doses of MTNX and adverse effects. The correlation of continuous variables was performed with the Spearman's nonparametric correlation coefficient. Results: 100% (14 patients) of the sample evacuated after MTNX with an average of 9 h 25 min. In terms of diagnosis 78.5% had neoplasic disease. At the time of application of MTNX, the patients PO morphine dose in 24 hours ranged from 15 mg to 250 mg with a mean of 71.4 mg. We found significant positive correlation between morphine dose and the time after MTNX subcutaneous administration and the first void (r = 1.000, p = 0.001) There was no correlation between the dose of morphine administered orally 24 hours and days constipation (r = - 0.195, P = 0.504) and between days of constipation and the time between MTNX subcutaneous administration and the first evacuation (r = -0.029, P = 0.923). 85.7% responded with a dose of MTNX, only 2 required a second dose. No adverse effects were reported in this study. Conclusions: these research showed us that all patients had a bowel movement after the application of MTNX. There is a correlation between opioid dose and response's time to MTNX. Neither opioid dose and constipation's days, or between day and response to MTNX. The results are preliminary since the size of the sample. Prospective studies are needed to verify efficacy and safety in the Mexican population.

: Opioid bowel dysfunction; Methylnaltrexone.

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