Opioid-induced hyperalgesia after rapid titration with intravenous morphine: Switching and re-titration to intravenous methadone.

BACKGROUND

Rapid titration with intravenous morphine (IV-MO) provides fast and efficient pain relief in cancer patients with severe-excruciating pain. However, some patients, after an initially favourable response, can develop an hyperexcitated state unrelieved or worsened by further dose increments.

METHODS

Eighty-one patients admitted on emergency basis titrated with IV-MO were assessed.

RESULTS

12 patients were unsuccessfully titrated with IV-MO. Switching to intravenous methadone (IV-ME) and titrating the doses proved to be successfully.

CONCLUSIONS

In escalating opioid doses rapidly a recognition of the development of hyperalgesia should be suspected. Increasing doses of opioids may stimulate rather than inhibiting the central nervous system, with complex mechanisms already recognized in experimental studies. Switching to IV-ME and titrating the doses could be taken into consideration to break this vicious circle before pain conditions worsen irreversibly.