Feb 22 (Reuters) - UK-listed drugmaker Indivior Plc said on Thursday it has started consulting shareholders on potentially shifting its primary listing to the United States by the summer of this year.

Indivior said the move would reflect its current and future growth opportunities since its proprietary treatments are U.S. centred and as the group's U.S.-based investors are nearing 50% of its overall shareholder base.

Such a move would add Indivior to a growing list of companies leaving London in recent years, fuelling fears that the city is rapidly losing its appeal.

Britain's struggle to attract IPOs and retain listed companies stems partly from London-listed groups being valued lower than those in the United States, investment bankers have said.

Among marquee companies, British chip designer Arm Holdings listed on the Nasdaq in September, preferring the U.S. financial hub of New York over a return to the London stock market.

Dublin-based building materials group CRH moved its primary listing from London to New York early last year, while a top investor in Pearson has called for the education firm to make the same switch. (Reporting by Aby Jose Koilparambil in Bengaluru; Editing by Savio D'Souza)