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Gazzetta Medica Italiana Archivio per le Scienze Mediche 2013 April;172(4):321-7


language: Italian

Morphine hyperalgesia

Ghio P. 1, Fassinotti S. 1, Dell’ Orco L. 2

1 Ospedale Cottolengo, Torino, Italia; 2 Chirurgia Multidisciplinare, Ospedale G. Bosco, Torino, Italia


In recent decades, the large and established use of morphine in different formulations, showed that they are effective drugs, powerful and secure, if prescribed correctly, with acceptable side effects and without other treatable and experience in the treatment of chronic pain particularly cancer, has confirmed it. This assertion, shared by all societies in the industry allowed to extend their use and to overcome existing negative concepts. Oppiofobia still, unfortunately, exists; this, however, is increasingly failing thanks to clinical evidence, and the courses and the recommendations of the Scientific Societies (SICP, SIAARTI). We have focused on one of the most rare side effects of morphine: the continued use, particularly if injected, may in some cases, develop over time polysymptomatic neurotoxicity, with paradoxical effect also in the perception of pain, according to our experience in the 0.5% to 0.8% of cases. The treatment on the NMDA receptor desensitization involves the intravenous administration of ketamine. Ketamine has a powerful effect on nociceptive pain and neuropathic pain, and is used differently in the field of anesthesia. The intravenous dose, as a “starter” of narcosis, is 2 mg/kg/d, continuous administration. It maintains hemodynamic stability. At this dosage it can lead to waking, hallucinations and dissociative phenomena. It must always be associated with sedatives, benzodiazepines preferentially. In the field of algology it has been proposed by us at a dose of 1 mg/kg/day, continuously in combination with midazolam, always assumed that the patient has not been already administered with benzodiazepine. Basically the dosage is: saline 500 mL + 50 mg + 10 mg of midazolam ketanest to 20 mL/hour, continuously, for a patient weighing 50 kg. Titration can last from 24 to 48 hours depending on the clinical response. We highlighted the case studies with ketamine. At this dose and with these precautions we have never observed confusion or dissociative phenomena, nor patients have complained about hypnotic hallucinations or fantasies. On the contrary, there is a recovery of the ability to communicate clearly.

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