What is Prialt?
Prialt is a solution for infusion containing the active ingredient ziconotide at concentrations of 100 and 25 micrograms per milliliter of solution.
What is Prialt used for?
Prialt is used in the treatment of severe and chronic pain (ie with a very long course) in patients where it is necessary to administer painkillers via intrathecal injection (puncture practiced in the space surrounding the spinal cord and the brain).
Given that the number of patients with chronic pain requiring the administration of intraspinal analgesics (pain medications injected directly into the spine) is scarce, the disease is considered 'rare' and, consequently, on 9 July 2001 Prialt was
designated 'orphan medicine' (ie medicine used for rare diseases).
The medicine can only be obtained with a prescription.
How is Prialt used?
Treatment with Prialt should only be performed by physicians experienced in the administration of intrathecal drugs. Prialt should be administered very slowly by continuous infusion via an intrathecal catheter (tube inserted into the spinal canal) and an infusion pump capable of delivering a precise amount of drug. Before use it may be necessary to dilute Prialt, particularly when the necessary doses are low, as happens at the beginning of the treatment. The initial dose is 2.4 micrograms per day. The dose can subsequently be increased every 1-2 days or after a longer interval until the point of equilibrium is found between the analgesic effect and any undesirable effects. In most patients the required daily dose is less than 9.6 micrograms. The maximum daily dose is 21.6 micrograms. The use of the medicine is not recommended in children.
How does Prialt work?
The active ingredient contained in the medicine, ziconotide, is the synthetic replica of a natural substance, the omega-conopeptide, extracted from the venom of a particular marine snail. Ziconotide acts by adhering to special ducts (calcium channels) present on the surface of nerve cells that transmit painful impulses. By blocking the penetration of calcium into nerve cells, ziconotide inhibits the transmission of painful impulses through the spine relieving pain.
What studies have been carried out on Prialt?
The effects of Prialt were first tested in experimental models before being studied in beings
human. Prialt has been the subject of three main studies involving a total of 589 patients with severe chronic pain, comparing their efficacy with placebo (a dummy treatment): two short-term studies (5 and 6 days), respectively on pain associated with cancer and pain not associated with cancer, and a third 3-week study on the use of the medicine in adult patients with severe chronic pain. In all the studies the main criterion for evaluating the efficacy was the variation of the VASPI score (visual analogue scale of pain intensity). This is a score assigned by the patient to the pain felt on the basis of a scale ranging from 0 mm (absence of pain) to 100 mm (maximum intensity of pain).
What benefit has Prialt shown during the studies?
In the first two studies, Prialt was more effective than placebo. Before treatment, patients had a VASPI score between 74 and 80 mm. After treatment, the value found in patients who received Prialt was 35 mm (cancer pain) and 54 mm (non-cancer pain), while the value in placebo-treated patients was 61 and 72 mm. In the third study, Prialt tended to be more effective than placebo, with a reduction in the VASPI score from the initial pretreatment value of 81 mm to 68 mm (patients treated with Prialt) and 74 mm (patients treated with placebo).
What is the risk associated with Prialt?
The most frequently observed side effects (ie more than 1 in 10 patients) are confusion, dizziness, nystagmus (uncontrolled eye movement), memory problems, headache, drowsiness, blurred vision, nausea, vomiting, irregular gait ( walking problems) and asthenia (weakness). For the full list of all side effects reported with Prialt, see the Package Leaflet.
Prialt should not be used in patients who may be hypersensitive (allergic) to ziconotide or any of the other components. Prialt should not be used in patients undergoing intrathecal chemotherapy (anticancer drugs injected into the spinal canal).
Why has Prialt been approved?
The Committee for Medicinal Products for Human Use (CHMP) concluded that Prialt offers an alternative to other painkillers with intrathecal administration, such as opioids, decided that the benefits of Prialt outweigh the risks for treating severe chronic pain in patients requiring intrathecal analgesia and has recommended the granting of marketing authorization for Prialt.
Prialt was authorized in "exceptional circumstances". This means that, given the rarity of the disease, it has not been possible to obtain complete information on Prialt. The European Medicines Agency (EMEA) reviews the new information available every year and, if necessary, updates this summary.
What information is still awaited for Prialt?
The company that makes Prialt is currently conducting a study on the use of the medicine in the long term, with particular attention to the possibility that the patient develops tolerance to the treatment (ie progressive reduction of the efficacy of the same dose of drug).
More information on Prialt
On 21 February 2005, the European Commission granted a marketing authorization valid for Prialt, valid throughout the European Union, to Eisai Limited.
The document officially designating Prialt as an orphan drug is available here. For the full EPAR for Prialt, click here.
Last update of this summary: 01-2007.
