Intravenous opioid testing in patients with chronic non-cancer pain.

The clinical use of an intravenous opioid testing can help to predict whether opioids will be beneficial. The determination of individual opioid responsiveness justifies subsequent long-term opioid treatment and is generally recommended. An overview over current testing procedures is given with particular regard to choice of opioid, maximum dose, determination of endpoints and duration of testing and recovery. Remifentanil testing is a new approch and is studied in a randomized placebo-controlled cross-over study in 24 patients suffering from severe non-cancer pain. An ascending infusion of remifentanil and placebo respectively was titrated against endpoints. The testing allowed a disctinction between 11 opioid-responders and 13 non-responders. Complete recovery after end of infusion was rapid with a reach of baseline conditions after 25 min in all patients. Thus the complete remifentanil testing procedure required at utmost 1 h. In conclusion, remifentanil testing offers a more rapid procedure allowing the routine use in an ambulatory setting.