One person is brain dead and five others are seriously ill after taking part in a drug trial for Portuguese pharmaceutical firm Bial at a clinic in north-west France.

The French health ministry said the six male patients aged 28 to 49 had been in good health until taking the oral medication. They started taking the drug on 7 January. One person started feeling ill on Sunday and the other five afterwards. The brain dead volunteer was admitted to hospital in Rennes on Monday. Other patients went in on Wednesday and Thursday.

Pierre-Gilles Edan, head of the hospital’s neurology department, said one man was brain dead, three others were suffering a “handicap that could be irreversible” and another had neurological problems. The sixth volunteer had no symptoms but was being monitored.

The French health minister, Marisol Touraine, said 90 people in total had taken part in the trial and received some dosage of the drug; others had taken a placebo. All trials on the drug have been suspended and all volunteers who have taken part in the trial are being called back.

The ministry said the test was carried out by the Biotrial clinic for Bial, which “specialised in carrying out clinical trials”.

The trial was intended to test for side-effects of the new drug but all trials at the clinic have been suspended and the French state prosecutor has opened an inquiry.

Touraine said the drug was a so-called FAAH inhibitor meant to act on the body’s endocannabinoid system, which deals with pain. Earlier reports suggested that the drug contained cannabinoids, an active ingredient found in cannabis plants, but the minister said it did not contain the drug or any derivatives of it.

Touraine said the study was a phase one clinical trial, in which healthy volunteers take the medication to “evaluate the safety of its use, tolerance and pharmacological profile of the molecule”.

Medical trials typically have three phases to assess a new drug or device for safety and effectiveness. Phase one entails a small group of volunteers and focuses only on safety. Phase two and three are progressively larger trials to assess the drug’s effectiveness, although safety remains paramount.

Testing had already been carried out on animals, including chimpanzees, starting in July, Touraine said.

Bial said it was committed to ensuring the wellbeing of test participants and was working with authorities to discover the cause of the injuries, adding that the clinical trial had been approved by French regulators.

Every year, thousands of volunteers, often students looking to make extra money, take part in such trials. Mishaps are relatively rare, but in 2006 six men were treated for organ failure in London after taking part in a clinical trial into a drug developed to fight auto-immune disease and leukaemia.

The men now apparently have a higher risk of cancer and autoimmune diseases tied to their exposure to the experimental drug.

Dr Ben Whalley, a neuropharmacology professor at Britain’s University of Reading, said standardised regulations for clinical trials were “largely the same” throughout Europe. “However, like any safeguard, these minimise risk rather than abolish it,” Whalley said. “There is an inherent risk in exposing people to any new compound.”

Agence France-Presse contributed to this story

