An obscure component of President Biden’s Inflation Reduction Act will jeopardize patients’ access to an entire class of medicines that could be key to beating cancer and reversing Alzheimer’s disease and other neurological conditions.

It’s crucial that Congress acts to fix this structural defect — and soon. Our policy environment should encourage drug companies to pursue the most promising potential treatments and cures, no matter what form they take. Unfortunately, the hastily written IRA is doing just the opposite.

Here’s the crux of the issue. The IRA permits the federal government to impose draconian price caps on a range of prescription drugs covered under Medicare. However, the law exempts newly approved medications from price setting for a specified number of years to allow drug makers time to recoup their upfront R&D investments.

Small molecule drugs — which are chemical compounds, usually pills — are exempt from Medicare price setting for nine years following FDA approval. That period is 13 years for biologics, which are more complicated, large-molecule drugs typically administered in a healthcare facility.

Unfortunately, that imbalance effectively penalizes small molecule drug development. Given that biologics afford investors four additional years to recoup their R&D funds under the IRA, drug makers are unsurprisingly shifting investment away from small molecules and toward biologics.

In most cases, one category of medicine can’t simply be substituted for the other.

Between 2017 and 2021 alone, uptake of small molecule oncology drugs increased by 5.4% annually.

Already, drug makers are warning that the so-called “small molecule penalty” is forcing them to reconsider R&D funding priorities. New small molecule oncology drugs could be a casualty — with little prospect of biologics subbing in for them directly. AstraZeneca CEO Pascal Soriot recently warned that his firm is reassessing oncology drug development because of the IRA.

An artificial bias toward biologics could also deepen healthcare disparities along socioeconomic and geographic lines.

For many patients, the key difference between small molecule drugs and biologics is convenience. Patients can pick up most small molecule drugs at the pharmacy counter and take them at home. Biologics often require administration by a trained healthcare professional.

Travel to and from a hospital or doctor’s office for treatment, as biologics sometimes require, makes care disproportionately burdensome for low-income and rural populations. In some cases, these barriers may cause patients to delay or forgo their medication altogether.

The cost of biologics places an additional barrier between vulnerable groups and their medications. On average, biologics cost about 22 times more than small molecule drugs. Beneficiaries typically have to absorb a substantial portion of these costs out-of-pocket through their insurance policies’ coinsurance cost-sharing responsibilities.

That can get expensive quickly, especially for seniors living on a fixed income. Already, the Centers for Medicare & Medicaid Services reports that nearly 15% of Medicare beneficiaries over 65 go without their prescriptions due to cost.

Favoring development of biologics over small molecule drugs simply doesn’t make any sense, financially or scientifically.

With Democrats in control of the White House and the Senate, there won’t be an opportunity to repeal the IRA’s drug price provisions in their entirety until at least 2025, and potentially later.

Not all hope is lost, though. Lawmakers on both sides of the aisle are increasingly supportive of amending the IRA to address the harmful small molecule penalty.

Republicans and Democrats alike have a duty to ensure equitable, affordable access to health care. Taking action to fix this unintended consequence of the law would do just that.

Dr. Wolfgang Klietmann is a former clinical pathologist and medical microbiologist at Harvard Medical School.