Warn MS patients on natalizumab about PML

Patients with multiple sclerosis considering treatment with natalizumab (Tysabri) should be warned of the risk of progressive multifocal leuco­encephalopathy (PML) before starting therapy and again after two years, the MHRA states in its latest Drug Safety Update (2010;3, Issue 8).

Thirty-one cases of PML have been reported with natalizumab (none from the UK), 23 after exposure for two or more years. The risk is approximately one to two cases per 1000 patients treated for at least two years.
    The MHRA also warns that use of fluoxetine during early pregnancy is associated with a small risk of congenital cardiac defects. The risk appears to be similar to that associated with paroxetine, increasing the absolute risk from one to less than two per 100.