Several dogs died in preclinical studies of the experimental pain drug that left one human volunteer dead, reports suggest.

French magazine Le Figaro said it had information to suggest dogs had died and others had sustained neurological damage in earlier testing of the experimental drug BIA 10-2474.

Responding to criticism that the French Medicines Agency (ANSM) agency had been slow to release information on the details of the trial director Dominique Martin told the newspaper the agency had given all the information it could given restrictions around what was “industrial property”.

Francois Peaucelle the General Director of Biotrial who ran the study said the death of the dogs was not significant: “The conclusions of this study were sufficiently clear and clean to rule out any particular ambiguity about proceeding with human tests,” he told French news agency BFM TV.

Earlier this year human tests of the Fatty acid amide hydrolase (FAAH) inhibitor known as BIA 10-2474 led to one fatality and four human volunteers with neurological symptoms of varying severity.

Le Figaro quoted treating neurologist Giles Edan as saying, “Four patients of the surviving five have neurological problems. Three have symptoms so severe that it leads us to worry that they will be disabled for the rest of their life. However, this prognosis is still not definitive.”

The British Journal of Clinical Pharmacology is to publish an editorial about the trial next month.