The drug-pricing measure passed by the U.S. House of Representatives as part of its big tax-and-spending bill may seem unimpressive.

A reflection of pared and compromised ambitions, it would initially let Medicare negotiate the prices of only 10 expensive prescription drugs — a fraction of the 250 covered by the Democrats’ original plan. It stands to save Medicare about $80 billion over 10 years — less than one-fifth of what was once envisioned.

Even so, this measure would be a game changer. America’s prohibition of any bargaining by Medicare has long kept U.S. drug prices among the highest in the world. If the Senate goes along with this change, it would wedge the door open.