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Avanir Pharmaceuticals has started enrolment of the first patient in AVR-133 study, a proof of concept, Phase II clinical trial investigating the use of its investigational drug AVP-923 for the treatment of levodopa induced dyskinesia (LID) in patients with Parkinson’s disease (PD).

In the proof-of-concept, double blind, randomised, crossover study, AVP-923 (45mg of dextromethorphan / 10mg of quinidine) will be compared with placebo to treat patients with LID.

About 16 PD patients will be enrolled in the Phase II clinical trial, which will be carried out at three sites in the US and Canada.

In the trial, enrolled patients will be given a two-week treatment with AVP-923 at random order and a two-week placebo treatment, separated by a two-week break.

In order to test the drug’s effect on dyskinesia, patients will be given a two-hour levodopa infusion at the end of each two-week treatment period.

During the six-week trial period, patients will be carefully monitored to see whether there are any side effects, Parkinson’s symptoms and general health status.

University of Toronto professor and director of the Division of Neurology Anthony Lang said: "Despite advances in PD therapeutics, many patients still suffer with poorly controlled dyskinesias, especially as they require higher doses of medications to increase dopamine levels.

"Dyskinesias can not only be disabling, but may also limit the dose of effective medications that treat core symptoms of PD."

"Dyskinesias can not only be disabling, but may also limit the dose of effective medications that treat core symptoms of PD."

According to the company, the top line data of the study will likely be released in the second half of 2014.

The results of this study are expected help inform future development of AVP-923 for LID treatment in PD patients.

AVP-923 is a combination of two well-characterised compounds including the active CNS ingredient dextromethorphan hydrobromide plus low-dose quinidine sulfate, which helps in increasing the bioavailability of dextromethorphan.

The investigational drug is currently being studied in several ongoing company sponsored Phase II clinical trials, including agitation in Alzheimer’s disease and neuropathic pain in multiple sclerosis.

Image: A Lewy body (stained brown) in a brain cell of the substantia nigra in Parkinson’s disease. Photo: courtesy of Marvin 101.