Shire Plc and Johnson & Johnson won the backing of Europe's highest court on Thursday in their battle for data exclusivity against a generic rival for Alzheimer's drug Reminyl, the court said.

The European Court of Justice (ECJ) backed the view taken by Britain's Medicines and Healthcare products Regulatory Agency (MHRA) that a product approved in a country before it joined the European Union -- and not upgraded since then -- should not be used as a reference for a generic product application.

Generics UK based its application for a generic version of Reminyl on the active ingredient Nivalin, authorized in Austria in 1963 -- way before the country joined the European Union, a country group that was then going under a different name.

The MRHA ruled the ingredient could not be used as a reference product and did not approve the application by Generics UK, a British distributor of medical products.

A medicinal product, such as Nivalin at issue in the main proceedings ... the placing of which on the market in a member state was not authorized in accordance with the applicable Community law, cannot be considered to be a reference medicinal product, the ECJ ruling said.

Shire, Britain's third-largest drugmaker, co-markets Reminyl in Europe with Janssen-Cilag AB, a unit of Johnson & Johnson.

Nivalin's original authorized use was for treating polio, although that was modified in 1995 to include experimental use in treating Alzheimer's disease, the Court said.

But it was not in dispute that the original dossier, on the basis of which Nivalin's marketing was authorized, was never updated in line with EU law now prevailing in Austria, it said. Alzheimer's is a degenerative condition for which there is no cure. An estimated 24 million people worldwide suffer from the memory loss and problems with orientation that signal Alzheimer's and other, less common forms of dementia.

Existing drugs, such as Reminyl, can ease symptoms but do not stop the disease.

(Reporting by Jeremy Smith; Editing by Dan Lalor)