Quinacrine, an oral drug used against malaria, has proven ineffective against prion disease, a deadly degenerative disorder of the brain, a study published by the journal The Lancet Neurology said Tuesday.
Doctors tested the drug among 107 patients with prion disease, who were assigned to a group that either took a 300-milligram dose of quinacrine daily or to another that did not take the treatment.
Seventy-eight of the patients died.
The death tally was somewhat lower in the quinacrine group, but after factors such as disease severity and type of disease were taken into account, there was no difference in survival.
The study was led by John Collinge, of the Prion Unit at Britain's Medical Research Council (MRC).
Prion diseases occur when a mutated form of the prion protein runs amok, destroying brain cells.
The term includes Creutzfeldt-Jakob disease (CJD), and a "variant" form that is the human equivalent of mad-cow disease, also called bovine spongiform encephalopathy (BSE).
Quinacrine was put to the test among human volunteers as it had been effective in lab-dish tests among mouse brain cells that had been infected with the rogue protein. The drug was "reasonably tolerated" among the patients, the study added.