A drug designed to treat an inherited form of amyotrophic lateral sclerosis (ALS) has received orphan drug designation from the US Food and Drug Administration (FDA).

Isis Pharmaceuticals said that its antisense drug ISIS 333611, which is designed to be delivered into the cerebral spinal fluid, has been given the nod from the FDA to treat patients with ALS.

Frank Bennett, the senior vice-president of research at the firm, said it was pleased at the designation, commenting: "ALS is a terrible disease in need of innovative and efficacious new therapies."

Also known as Lou Gehrig's disease, ALS is a serious neurological disease which attacks neurons controlling the voluntary movement of muscles that can result in death.

The National Institute of Neurological Disorders and Stroke say that most patients who have the disease die from respiratory failure between three and five years after they first start experiencing symptoms.

Healthcare providers who need to obtain drugs for patients suffering from rare conditions can contact Masters, which has many years experience sourcing drugs from manufacturers across the world.