Scientists May Finally Know Why Statins Cause Muscle Pain

By Pat Anson

Many people stop taking cholesterol-lowering statins because they experience painful muscle cramps, weakness, and fatigue. I know, because I was one of them.

I started taking statins in my 40’s on the advice of our family physician, because of mildly elevated cholesterol and a family history of coronary artery disease. Soon I was having stinging cramps in my legs overnight, which were painful enough to wake me up. 

My doctor was skeptical that statins were the cause, but switched me from Lipitor to Vytorin and finally to Crestor. The muscle cramps continued. Only when I stopped taking statins did the symptoms disappear.

“I’ve had patients who’ve been prescribed statins, and they refused to take them because of the side effects. It’s the most common reason patients quit statins, and it’s a very real problem that needs a solution,” says Andrew Marks, MD, Professor and Chair of the Department of Physiology and Cellular Biophysics at Columbia University.

To find a solution, first you need to identify the cause, and Marks and his colleagues have finally discovered why about 10% of people on statins experience those muscular side effects.

Their research, recently published in The Journal of Clinical Investigation, found that a widely-used statin called simvastatin (Zocor) binds to a protein in muscle cells, which causes a leak of calcium ions inside the cells.

Using an electron microscope, researchers watched simvastatin molecules bind to two locations in a muscle protein called the ryanodine receptor, which opened a channel in the receptor that allowed calcium to flow through. 

Marks says the calcium leak could be weakening the muscle directly or by activating enzymes that degrade muscle tissue.

“It is unlikely that this explanation applies to everyone who experiences muscular side effects with statins, but even if it explains a small subset, that’s a lot of people we could help if we can resolve the issue,” Marks said in a press release.

The electron images suggest that statins could be redesigned so they don’t bind to the ryanodine receptor, but retain their cholesterol-lowering ability. 

Marks is now collaborating with chemists to create such a statin. He owns stock in RyCarma Therapeutics, a company developing compounds that target the ryanodine receptor.

Plugging the calcium leak could be another option: Statin-induced calcium leaks in laboratory mice can be closed with an experimental drug developed by Marks for other muscle conditions involving calcium leaks.

“These drugs are currently being tested in people with rare muscle diseases. If it shows efficacy in those patients, we can test it in statin-induced myopathies,” Marks says.

The first statin was approved by the FDA in 1987, but it took the agency nearly three decades to listen to patients like me and update warning labels on statins in 2014, cautioning that statins can cause myopathy. In rare instances, the FDA says statins can also cause liver injury, diabetes and memory loss.