Washington: US regulators on Thursday approved Repatha, the second injectable drug of its kind designed for certain patients with stubbornly high cholesterol which puts them at risk of heart disease.

Repatha, also known as evolocumab, is made by Amgen and is part of a new class of drugs known as PCSK9 inhibitors, or antibodies which work on the liver to lower cholesterol.

It was approved by the US Food and Drug Administration for people with inherited conditions that cause high levels of low-density lipoprotein (LDL), or bad cholesterol, as well as people whose clogged arteries have led to heart disease.

High LDL cholesterol in the blood causes plaque buildup in the arteries and eventually heart disease, which is the leading cause of death for Americans killing 610,000 people every year.

‘Repatha provides another treatment option in this new class of drugs for patients with familial hypercholesterolemia or with known cardiovascular disease who have not been able to lower their LDL cholesterol enough with statins,’ said John Jenkins, director of the Office of New Drugs at the Center for Drug Evaluation and Research.

One study on Repatha showed that patients taking it for 12 weeks saw a 60 percent reduction in LDL levels, compared to patients taking a placebo.

Side effects may include upper respiratory tract infection, flu, back pain and reactions such as redness, pain or bruising where the injection is given. Some patients may have allergic reactions, the FDA said.

An advisory panel to the FDA recommended the drug's approval in June.

In July, the FDA also approved Praluent (alirocumab) by Sanofi and Regeneron Pharmaceuticals.

Some experts say these new drugs offer an alternative to popular anti-cholesterol drugs known as statins (Lipitor, Crestor and others) which are not tolerated by all patients.

Data on whether the new drugs actually lead to longer lives or less heart disease will not be available until 2017.

Pharmaceutical companies say the drugs could help between eight and 11 million Americans.

Analysts say the drugs could generate more than $2.5 billion annually for each of the pharmaceutical companies that make them.