[New drugs; natalizumab].

The drug natalizumab represents a new pharmacological approach in the treatment ofvery active relapsing-remitting multiple sclerosis (MS). It is a humanised murine monoclonal antibody and binds to an integrin on the surface oflymphocytes, thereby preventing them from transmigrating across the endothelium and causing inflammation in the nervous tissue. The drug has been shown to decrease the occurrence of relapses and progression of MS. A few severe adverse effects (such as the viral progressive multifocal leuko-encephalopathy) have been reported, and its clinical and long-term effects are not fully known at present. Therefore, further research is required to determine the role of natalizumab in clinical practice.