BRANFORD, Conn. – Biotechnology company Neurogen Corp. said Sunday it stopped a clinical trial of its insomnia candidate adipiplon because some patients experienced grogginess and memory loss. The stock plunged in Monday trading.
The Branford, Conn.-based company is developing immediate-release and controlled-release forms of the drug, and was testing a tablet that combined both versions. Neurogen said the combined drug may not be working as expected, leading to “a higher-than-anticipated rate of unwanted next-day effects” in the phase 2/3 trial.
The side effects were described as “significant grogginess and amnestic events,” similar to the effects of a too-large dose. Neurogen said the side effects were not serious and none of the patients who experienced them quit the study.
Patients have received both kinds of adipiplon in previous trials, but this is the first trial of the combination tablet. Neurogen said it expects to take two to three months to investigate the side effects.
“We are disappointed by this setback,” said Stephen R. Davis, president and chief executive of Neurogen, in a statement. “We do not yet know whether there is a path forward with lower doses of the existing formulation or whether further formulation development would be required.”
Neurogen shares skidded 34 cents, or 33.3 percent, to 68 cents in morning trading. The stock earlier fell to an all-time low of 55 cents.
The trial compared 6-mg and 9-mg doses of adipiplon to a placebo and to a 12-mg tablet of Ambien CR. Both doses of adipiplon contained 1 mg of the immediate-release formulation.
Davis said the company may consider resuming testing with a smaller dose of adipiplon or changing the composition of the drug, as past trials have shown it works in doses as low as 3 mg. But that may not happen due to financial and time constraints, he said.
The trial was slated to include a total of 84 patients, who would have been given each of the four tablets in random order. About 15 or 17 patients had received each tablet when the trial was stopped.
