Merck is working on drugs to raise the level of good cholesterol (HDL). Higher levels of HDL cholesterol can reduce the risk of heart disease and possibly even reduce plaque build up in the arteries.

The current leading drug for boosting HDL cholesterol is problematic, because it often causes severe side effects in the skin. This has limited its popularity and usefulness.

Merck is currently developing a similar drug, but one that will not have those troublesome side effects. Merck has two HDL boosting drugs that work in different ways in late stage clinical testing. Unfortunately, neither of these drugs is likely to hit the market for several years, and may not be approved at all, depending on the trial results and the FDA.

If Merck does manage to get an effective HDL boosting drug on the market that lacks major side effects, it will likely be a huge blockbuster drug along the lines of their bad cholesterol reducing drug Lipitor.