LONDON, Oct 25 (Reuters) - Britain's biggest drugmaker GlaxoSmithKline is moving ahead with Brexit contingency planning "right now", including preparing a system to test drugs in the European Union if Britain crashes out of the bloc without a trade deal.
Drugmakers are particularly affected by Brexit because of the highly regulated nature of their business.
Chief Executive Emma Walmsley said drug companies needed clarity on future relations with the EU as soon as possible to minimise disruption to medicine supplies and repeated her earlier plea for a transition period of at least two years.
Although the impact of Brexit on GSK's overall business will not be material, as Britain accounts for only 4 percent of sales, GSK needs fall-back arrangements, including a way to retest UK-manufactured batches of drugs shipped to Europe.
"It is mainly related to the construction of new testing facilities across Europe and potential preparations for licence changes as well," Walmsley said of the company's contingency planning.
"All of that work is underway in the detailed planning group, and we will be ready for it as necessary."
She made her comments to reporters after announcing quarterly results on Wednesday.
Britain has a large pharmaceuticals sector and produces many medicines used in Europe and other countries. A disorderly exit from the EU in March 2019 with no system in place to ensure drug supplies would threaten those supply lines.
Drug companies want to remain within the European regulatory system as far as possible, even as the London-based European Medicines Agency prepares to relocate to another city inside the EU as a result of Brexit.
Brexit minister David Davis said on Wednesday he was aiming for an outline Brexit transition deal by the first quarter of 2018. Businesses across all sectors are anxious to see the details of such a deal as they draw up investment plans for the year ahead. (Reporting by Ben Hirschler; Editing by Mark Potter)