One bill provision would forbid "spread pricing," or the practice of PBMs establishing a set price for a prescription drug and then taking responsibility for any difference between the set price and what the PBM actually pays the pharmacy.

The PBMs say spread pricing gives employers certainty about drug pricing. Pharmacies say PBMs use spread pricing to hide the real prices of drugs from employers, underpay independent pharmacies, and profit from the gap between what employer plan sponsors pay and what the pharmacies actually get.

Another PBM provision would forbid a PBM from steering patients toward its own, PBM-owned or PBM-affiliated pharmacy or discriminating against non-affiliated pharmacies.

Related: California lawmaker aims to reduce drug costs, rein in PBMs with 2 new bills

The bill was introduced by state Sen. Scott Wiener, D-San Francisco. "This bill reins in the worst abuses by PBMs, insurance-industry middlemen who are driving up the price of prescription medication for Californians" according to a statement by Weiner included in a state Senate legislative analysis.

When big PBMs buy pharmacies and steer patients toward their own pharmacies, that undermines health care access and drives up the cost of drugs, Weiner says.

Pharmacist groups and some patient groups are backing the bill.

The list of opponents includes the California Chamber of Commerce and two labor organizations, AFSCME Local 685 and Service Employees International Union 721, Bargaining Unit 702, in addition to health plan, health insurer and PBM groups.

The California Chamber of Commerce says enacting the bill would "disrupt the use of carefully balanced pharmaceutical benefit designs and financial incentives, leading to increased drug costs for patients and higher health care costs for employers," according to a statement posted on the chamber's website.

Making sure that employers know what PBMs are really paying pharmacies for drugs is a good idea, but banning spread pricing entirely would eliminate a tool that helps employers lock in prices for drugs, the chamber says.

Limiting plans' ability to steer patients toward pharmacies in preferred pharmacy networks would weaken another strategy employers and their drug plans have to bargain for lower drug prices, the chamber says.

The governor question: Before the bill can become law, it must pass in the California Assembly and be signed by California Gov. Gavin Newsom, a Democrat.

If the Assembly changes the bill, the Senate must vote on the amended version.

Newsom vetoed a Wiener PBM licensing bill in September 2024. Newsom said at the time the state should get more information before enacting a new PBM law.

But Newsom said last month that strengthening licensing, reporting and operational review requirements for PBMs is one of his top priorities. Newsom put PBM oversight update provisions in his own budget plan.

Other legislative news: California state bills with a chance to become law are starting to pull away from the pack.

The California Assembly passed a bill in May that could require private equity firms and hedge funds involved in health care deals to file disclosure reports with the California Office of Health Care Affordability. The bill, which was approved by a 42-16 vote in the Assembly, is now under consideration in the state Senate Health Committee.

The Assembly passed a bill Monday that could prevent artificial intelligence systems from presenting themselves as doctors, nurses or other certified health professionals. The bill passed by a voice vote.