Carbamazepine Withdrawal-induced Hyperalgesia in Chronic Neuropathic Pain

Combined pharmacological treatments are the most used approach for neuropathic pain. Carbamazepine, an antiepileptic agent, is generally used as a third-line treatment for neuropathic pain and can be considered an option only when patients have not responded to the first- and second-line medications. In the case presented herein, a patient with neuropathic pain was treated using a combined pharmacological regimen. The patient's pain deteriorated, despite increasing the doses of opioids, when carbamazepine was discontinued, potentially because carbamazepine withdrawal disrupted the balance that was achieved by the multifaceted pharmacological regimen, thus inducing hyperalgesia. Interestingly, when carbamazepine was prescribed again, the patient's pain was successfully managed. Animal research has reported that carbamazepine can potentiate the analgesic effectiveness of morphine in rodent models of neuropathic pain and postoperative pain. This clinical case demonstrates that carbamazepine may have a synergistic effect on the analgesic effectiveness of morphine and may inhibit or postpone opioid-induced hyperalgesia. We postulate that a probable mechanism of action of carbamazepine may involve -aminobutyric acid-ergic potentiation and the interruption of glutamatergic function via N-methyl-D-aspartate receptors. Further research is warranted to clarify the analgesic action of carbamazepine and its potential use for the prevention of opioid-induced hyperalgesia in chronic neuropathic pain patients.