Abstract

MERCEDES, Patricia Papa. Modalidades de rotación morfina a metadona en pacientes con dolor oncológico. Rev. Méd. Urug. [online]. 2009, vol.25, n.2, pp.124-130. ISSN 1688-0390.

Summary Introduction: morphine continues to be the fundamental stone in pharmacological treatment of oncologic pain. However, there is a group of patients who present an inadequate analgesic response to this opioid analgesic or develop unbearable side-effects. For them, methadone seems to be a good analgesic alternative, since it does not contain active metabolites and presents wide bioavailability, although its long and unpredictable average life and the lack of standardization in equianalgesic dose result in their drug potency and toxicity risk to be higher than expected. Objective: to analyse the fundamentals and prescriptions that justify rotating to opioids, by providing an update of the modalities of rotation from morphine to methadone and viceversa, that are suggested for clinical practice. We assessed the existing evidence concerning equianalgesic tables and doses taken from studies of patients who tolerated opioids and patients who had never taken opioids. Method: we studied bibliography published in English and Spanish in the MEDLINE, PUBMED and COCHRANE databases, from 1995 through 2008. Conclusions: according to the data available, opioid switching enables clinical improvement in over 50% of patients with oncologic pain who had a poor response to opioids. Equianalgesic tables must be regarded as guidelines that ignore the wide interindividual variation to opioids. The process geared to achieving the best dose must be highly individualized.

Keywords : PAIN - therapy; MORPHINE - administration & dosage; METHADONE - administration & dosage.

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