Pharmacies throughout California could soon dispense an HIV-prevention drug without a doctor’s prescription — a move a San Francisco state senator says is necessary to remove barriers to people’s access to medication that could end new infections.

Democratic Sen. Scott Wiener has proposed a bill that would allow people to receive their first 30 days of PrEP, an oblong blue pill sold under the trade name Truvada, over the counter if they first receive counseling and an HIV test.

He said the proposal, SB159, would help prevent infections by expanding patient access to the drug, particularly among gay and bisexual men of color, who use it less commonly than whites.

But the bill faces opposition from the California Medical Association, which represents doctors, and major insurance companies. They say Truvada has potential side effects, including impaired kidney function, and that people who take it need to be closely monitored by doctors.

SB159 passed the Senate last week with nearly unanimous support, and now moves to the Assembly.

PrEP, or pre-exposure prophylaxis, dramatically reduces the chance that an HIV-negative person who has sex with a positive partner will contract the virus, if the drug is taken daily. Clinical studies show Truvada is 99% effective, according to the San Francisco AIDS Foundation.

Wiener and HIV-prevention advocates said many people who want PrEP can’t get prescriptions easily and could become infected as a result.

“There are still way too many barriers” for people trying to obtain PrEP, Wiener said.

Proponents of easier PrEP access say many people at risk of HIV infection don’t take the drug because they face long waits to see a doctor who can prescribe it. That’s especially true for Medi-Cal patients and people in rural areas where there are few physicians, they say.

Another hurdle is a stigma against PrEP or anti-LGBTQ bias among some doctors who deny patient requests for the drug, proponents say.

“It’s not easy to navigate the system,” said Dr. Stephanie Cohen, medical director of the San Francisco Department of Public Health’s City Clinic. “This is something that really needs to be low-barrier access for folks. But it’s just not that way across the whole state.”

PrEP has helped San Francisco reduce its HIV infection rate to record lows, particularly among white gay and bisexual men. SB159 has been endorsed by the San Francisco Department of Public Health, the AIDS Foundation, Equality California and the California Pharmacists Association.

However, the bill also faces powerful opposition.

Sen. Brian Jones, R-Santee (San Diego County), who cast the lone dissenting vote when the Senate passed the bill, said he’s concerned that PrEP can be “very hard on one’s kidney and liver and therefore should be prescribed by a doctor” who can do proper blood tests.

Those objections are similar to concerns raised by the California Medical Association, the state’s largest physicians lobbying group. In a letter to lawmakers, the association said providing PrEP without a doctor’s prescription would be “irresponsible.”

The association argues that a physician’s oversight is necessary from the get-go to ensure patients are properly tested and fully informed about PrEP’s potential risks.

“Physicians do not provide a prescription for any drug simply because that patient has asked for it,” the group said.

Wiener pointed out that his bill would require pharmacists to counsel patients and order lab tests to screen their kidney function. If a problem is detected, the bill would require pharmacists to contact the patient.

SB159 also would require pharmacists to refer PrEP patients to a primary care doctor so they can continue care after their first 30-day supply of Truvada runs out.

Wiener said patients should be trusted to make informed decisions about their own health.

“People know their own lives best,” he said. “People know when they are at risk.”

The bill would prohibit insurance companies from requiring patients who want PrEP to receive preauthorization from the insurer, a review process to determine if the drug is medically necessary. That can delay their access to the drug.

In 2014, Wiener made national headlines when he announced he took PrEP daily. Wiener, then a San Francisco supervisor, was the first elected official in the country to make such a declaration.

At the time, PrEP had been on the market for only about two years, and many doctors wouldn’t prescribe it because they were unfamiliar with the medication.

Since then, the drug has become mainstream in the LGBTQ community. San Francisco has led the nation in reducing infection rates, but inequities in PrEP access have become pronounced.

“The lowest uptake has been among populations of color,” said Courtney Mulhern-Pearson, senior director of policy and strategy for the San Francisco AIDS Foundation. “Stigma is obviously a huge barrier.”

PrEP use varies significantly among racial groups, according to 2017 data from the Department of Public Health’s City Clinic. While about half of eligible white, Asian American and Latino male patients who have sex with men were taking the pill, only a third of black men were.

Proponents said that while access has gradually improved in San Francisco, they still find lower use among Latino men who have sex with men and transgender women, especially outside the city.

Pharmacist Maria Lopez said community pharmacies could be a critical tool to address that disparity. Her store, Mission Wellness Pharmacy near 20th and Mission streets, began offering PrEP directly to patients about a year ago. The program is the first of its kind in California, a new partnership with the Department of Public Health.

Lopez said her team has filled the void for several patients who otherwise faced a two- to three-month wait to see a doctor for a basic PrEP prescription.

“We can play an important role in the community by increasing PrEP access and educating the public,” she said. “We know of patients who were unable to see a doctor, and that’s why they came to see us.”

But even if Wiener’s bill becomes law, advocates say another potential barrier to PrEP access remains: Truvada’s hefty price tag.

The retail cost for a patient without insurance typically exceeds $1,800 per month, and Truvada manufacturer Gilead Sciences Inc. has effectively cornered the market.

Most insurers and Medi-Cal cover the drug. But other patients with high insurance deductibles and cost-sharing plans can face large out-of-pocket costs.

Gilead offers a co-pay card to help patients cover the cost and recently increased its per-patient-assistance limit to $7,200 per year. But Cohen said some people who could take the drug don’t because they don’t know about the program.

Dustin Gardiner is a San Francisco Chronicle staff writer. Email: dustin.gardiner@sfchronicle.com Twitter: @dustingardiner.