Heart disease patients taking a new class of drugs to reduce cholesterol do not experience an increase in side effects such as memory impairment or nervous system disorders, but may have an increased risk of cataracts, according to a study led by a UI College of Public Health researcher.

However, the researcher says the results likely will not change the use of statins as the primary drug to reduce cholesterol levels and other cardiovascular risks.

The new class of drugs—called PCSK9 inhibitors—were studied in combination with statins to lower LDL cholesterol, or “bad cholesterol,” in high-risk patients unable to lower cholesterol levels using only statins or other lipid-lowering therapies. Statins are a class of drug often used to reduce cholesterol levels.

The study sought to address concerns about how very low levels of LDL cholesterol affect body functions that rely on cholesterol, including hormone production, digestion, and healthy cell structure.

“The safety of these new drugs is critical to patients who have no other means by which to control their life-threatening high cholesterol,” says the study’s lead author, Jennifer Robinson, UI professor of epidemiology and medicine and director of the UI Preventive Intervention Center. “The long-term effects of very low levels of LDL cholesterol are under evaluation in ongoing large clinical trials.”

The study appears in the Feb. 7 issue of the Journal of the American College of Cardiology, which was published online on Jan. 30.

Researchers pooled data from 14 random, controlled studies that included 5,234 patients treated with the PCSK9 drug alirocumab for up to two years. They looked for side effects in patients who achieved two or more consecutive LDL cholesterol values below a level considered to be necessary for normal cell function.

The overall incidence of side effects was similar in patients taking alirocumab versus those taking a placebo. Adverse symptoms included musculoskeletal disorders, neurologic and neurocognitive conditions (including memory impairment), and renal or liver problems. An increased incidence of diabetes was not detected, despite previous studies showing more patients than normal contracted the disease.

Analyses did show an increased incidence of cataracts in patients with low LDL, and though the cause was unclear, researchers say it could be because reducing cholesterol accelerates underlying aging-related changes, contributing to cataracts.

While the study suggests the very low levels of LDL cholesterol were well-tolerated in limited trials, the long-term effects of PCSK9 inhibitors remain unknown, according to Robinson. As a result, she says statins remain the mainstay of cardiovascular risk reduction therapy.

“Statins have an excellent record of safety in properly selected patients,” says Robinson. “Therefore, every effort should be made to maximize statin therapy before considering adding a nonstatin such as alirocumab to further reduce LDL-C levels.”