[What became of Prialt®? : Observational study on the use of ziconotide in the treatment of chronic pain].

BACKGROUND: Prialt® was approved by the European Medicine Agency in February 2005. Besides morphine, it is the only analgesic approved for long-term intrathecal infusion in the treatment of chronic pain. As it does not bind to opioid receptors, its use in the treatment of chronic pain seemed to be safer and to lead to less adverse events compared with morphine. However, it is an orphan drug and studies of its long-term use are rare.

QUESTIONS: What role does Prialt® play in the treatment of chronic pain compared with other analgesics given intrathecally? What impact do the initial dose and the rate of infusion have on the analgesic effect and on the incidence of side effects?

MATERIAL AND METHODS: Medical reports were used to identify all patients receiving ziconotide monotherapy from February 2005 to the end of the analysis period in October 2018 in our department. Furthermore, a questionnaire was created and given to the patients to find out more about their experience with ziconotide.

RESULTS: The study included 12 patients, all of whom suffered from at least one adverse event. The most common adverse events were forgetfulness and paraesthesia, each affecting 25% of the patients. One third of the patients discontinued ziconotide therapy due to severe adverse events. The mean initial dose was 1.98 µg/day.

DISCUSSION: Ziconotide was used at the Jena University Hospital according to the latest guidelines. Nevertheless, morphine and other opioid analgesics are still more frequently used in the intrathecal management of chronic pain. There are various reasons for this, but the narrow therapeutic index, the high incidence of adverse events, and the difficulties in finding the right dose are among the most important.