The Senate overwhelmingly passed a bill on Monday that would prohibit a controversial practice through which insurers and drug middlemen prevent consumers from paying less at the pharmacy counter on prescription drugs.

Monday’s legislation, which passed by a 98-2 margin, would prohibit insurers and drug middlemen called pharmacy benefit managers from inserting “gag clauses” into contracts with pharmacies. The clauses prohibit pharmacists from informing consumers it is cheaper to buy a drug out-of-pocket rather than through their insurance.