Can you tell me about a drug combination my doctor prescribed to lower my cholesterol?

DEAR DOCTOR K:

Despite taking statins, my cholesterol hasn’t dropped as low as my doctor would like. I figured he’d put me on the new PCSK9 inhibitors. Instead, he suggested that I stay on my statin, but also take another drug called ezetimibe. What can you tell me about this combination?

DEAR READER:

From what you say, I assume your doctor has used the highest dose of the most potent statins before giving up on those drugs. There are very few people whose cholesterol does not drop substantially on statins alone.

However, if your cholesterol still is not low enough despite maximizing statin treatment, then you do need something else. The cholesterol-lowering drugs known as PCSK9 inhibitors roared onto the market last year. Thanks to their impressive performance in clinical trials — in one year, they lowered LDL (“bad”) cholesterol levels by 40 to 60 percent — doctors and patients alike greeted them with excitement. But these drugs aren’t for everyone.

Why? One big reason is cost. PCSK9 inhibitors cost an estimated $14,600 per year. Did I just hear you gulp? I thought so. By contrast, most statins are available as generics. They can cost as little as $4 per month through discount programs at large chain stores.

Moreover, the statins have been proven to decrease actual heart attacks and strokes. Doctors do not yet know if the PCSK9 inhibitors will ultimately do the same. Finally, PCSK9 inhibitors are given by injection every two to four weeks, whereas statins are pills.

But when statins alone do not adequately lower LDL cholesterol, there are other options than the PCSK9 inhibitors, as well.

One alternative is ezetimibe (Zetia). This drug blocks cholesterol in food from crossing the intestinal wall and getting into the bloodstream. It can lower LDL levels by roughly 15 to 20 percent when used alone. And when added to statins, it can lower cholesterol further. Ezetimibe has an excellent safety record and is generally well tolerated.

One large study compared adding ezetimibe to the statin simvastatin (the combination found in the drug Vytorin) to using one of the statin drugs (simvastatin) alone. The combination was more effective in preventing heart attacks and strokes.

The study included more than 18,000 people who were recovering from heart attacks. After six years, LDL levels in the ezetimibe-plus-simvastatin group dropped considerably lower than in the group taking just simvastatin. More important, comparing a theoretical group of 100,000 people taking the combined drugs to a group of the same size taking just the simvastatin, 2,000 more people taking just simvastatin would have had another heart attack or a stroke.

Ezetimibe works when added to any statin. If the combination of a statin plus ezetimibe doesn’t work for you, then your doctor may consider a PCSK9 inhibitor.

Not all insurance companies pay for PCSK9 inhibitors. Those that do need proof from your doctor that every other way to lower your cholesterol has not produced adequate results. Hopefully, adding ezetimibe will do the trick. I’ll bet it will.