METHADONE CONVERSING USING IN THREE PATIENTS WITH CANCER ON HIGH-DOSE OPIOIDS: TWO MODELS SWITCH STRATEGY “3-DAY” OR “STOP AND GO”: PAIN-RELIEF, MISTRUST, ENVIRONMENTAL DIFFICULTIES

M. Forte¹, M. Cascella², I. Iannone¹, C. Abagnale¹, N. Gallo¹, A. Alfano¹, F. Monaco³, C. Della Corte¹, F. Morgillo¹, T. Troiani¹, M. .C. Pace¹, P. Sansone¹, M.B. Passavanti¹ | ¹Università degli Studi della Campania AOU “L. Vanvitelli”, Napoli, Italy; ²Università degli Studi di Salerno, Fisciano (SA), Italy; ³Ospedale San Paolo, Napoli, Italy

Background. Methadone is a long-acting non-competitive NMDA receptor antagonist, with an elimination half-life of approximately 8-60h; it is used in the management and treatment of opioid use disorder and for analgesic purposes in chronic and cancer pain.
Target. Evaluate the response to methadone therapy, pain relief and side effects in patients receiving high-dose opioid therapy without pain relief. We report a case series of three patients with cancer pain, all undergoing long-term treatment with high-dose opioids, switched using equianalgesic doses. We guaranteed a continuous telephone contact with the patients to evaluate their adherence to the new therapy.
Case Report 1. 60-year-old patient with SCLC and bone metastases, undergoing immuno-, chemio- and radiotherapy. He reported diffuse pain in the right hemithorax (NRS=9) and he was treated with increasing doses of morphine, a SAP block and he was switched to oxycodone and ROO for frequent BTcP. After 4 months of pain relief and improvement, the pain returned (NRS=8-9).
Case Report 2. 48-year-old patient with lung cancer and bone metastases. He reported uncontrollable pain which was treated with a SAP block in the outpatient clinic and then converted to opioids.
Case Report 3. 39-year-old patient with gastric cancer, treated for 1 year with high-dose opioids; he was switched to high-dose oxycodone, fentanyl transdermal patch and ROO without pain relief. All patients were advised about the changing of the therapy with methadone after assessing that their liver and cardiac functions were in normal limits. For patients with lung cancer we proceeded with SAG according to Mercadante(1), while the younger patient with gastric cancer did not accept the replacement of the current therapy and “3-day rule” was proposed.
Discussion. We administered methadone 20mg p.o. twice daily to all patients and after 48h the dose was halved. The patients reported immediate benefit and no side effects. However, the younger patient complainded of drowsiness and loss of appetite and after 2 weeks he returned to his previous therapy on his own. The pain recurred and he agreed to the placement of an intrathecal device. We noted that all patients had difficulties in obtaining adeguate methadone availability; two patients had a shortage for 2 days, however they did not have any pain episosed due to the drug’s long half-life.
Conclusions. In our experience, methadone provided effective analgesia with no side effects and has proved to be an excellent drug as a follow-up to treatment with morphine, oxycodone or fentanyl in patients with no pain relief, opioid-induced hyperalgesia and wind up. Despite its advantage, the use of methadone is complicated by interindividual variability and fears about switching and it presented a serious problem regarding supply and proper commercial distribution in sufficient dosages. This drug requires a physicians-patient relationship to overcome both external market and psychological barriers, as all our patients to whom it is offered are always afraid of leaving the safety of their ongoing therapy, even if it is no longer effective.