TORONTO — The distributor of a psoriasis drug that is the subject of safety concerns has agreed to suspend sales of the medication in Canada. Health Canada recommended that EMD Serono Canada Inc. stop the marketing of Raptiva, the brand name for the drug efalizumab. Raptiva was authorized in October 2005 for treatment of moderate to severe chronic plaque psoriasis in patients 18 years of age and older. But use of the drug has been linked to cases of a condition called progressive multifocal leukoencephalopathy or PML, a severe and sometimes fatal neurological disease. And other serious infections have been seen in people who have taken the drug for three years or more, including Guillain-Barre syndrome, encephalitis, meningitis and sepsis, a bloodstream infection. The European drug regulatory agency has already decided that the medication's risks outweigh its benefits. On Thursday, the U.S. Food and Drug Administration warned doctors and people taking the drug that it has received reports of three confirmed cases and one possible case of PML in Raptiva users. All four patients were treated with Raptiva continuously for more than three years. Three of the four people have died. There is no known effective treatment against PML. The FDA, which required Raptiva manufacturer Genentech to put a boxed warning on the drug packaging last fall, said Thursday it is in the process of reviewing the latest data. The agency's statement said there were no cases of PML seen among people who took part in the clinical trials used to bring the drug to market. At the time the FDA licence was granted, a total of 2,764 patients had been treated with Raptiva. But the data submitted for licensure was not based on long-term use of the drug — 2,400 of the participants had been treated for three months, 904 for six months and only 218 for one year or more. Late Friday, Health Canada distributed statements for the public and for physicians from EMD Serono explaining that the suspension of sales in Canada is needed to ensure patient safety. Doctors were warned not to prescribe Raptiva for new patients and to figure out a new treatment option for patients currently taking the drug as soon as possible. Supplies of the drug will no longer be available in the country within a few months, the statement said. Meanwhile, people taking the drug were told they should see their doctor as quickly as possible to find an alternative treatment regime, but not to stop taking the drug without consulting a doctor. Abrupt discontinuation of the drug without alternative treatment could trigger a return of psoriasis or onset of new psoriasis, the statement said.