What is the difference between Albuterol (Proventil) and Levalbuterol (Xopenex)?
Well, their mechanism of action is the same. They both act on beta-2 adrenergic receptors (which are concentrated on your bronchial passages) to get them to dilate or open up. The only “difference” is that Levalbuterol is an R-enantiomer-only drug, whereas Albuterol has both R and S-enantiomers. This is organic chem which I don’t know if you’re familiar with, but an enantiomer is basically a way to arrange different chemical groups on one molecule (right to left, or left to right). The problem with drugs that act on beta receptors is that they can also act on the heart and make it beat faster (and a too-fast or tachycardic heart is a problematic side effect). Some studies claim that because Levalbuterol is an R-enantiomer only drug, it has fewer side effects on the heart compared to Albuterol. But this has not been consistently shown. So the distinction in practical terms is iffy at best.
