A molecule’s ‘handedness’ can determine whether it’s an effective drug – 4 examples of pharmaceuticals where chirality matters

The 2026 Nobel Prize in chemistry went to Henri Kagan and Kenso Soai for work on chirality, the mirror-image handedness found in molecules, snail shells, and human hands. Kagan showed in the 1980s that an imperfectly pure catalyst can still yield a purely single-handed product, while Soai in the 1990s found a self-copying molecule that amplifies a tiny imbalance into near-total one-handedness.

The piece traces why this matters in medicine through four drugs. Thalidomide's two mirror forms converted into each other in the body, meaning even a single-handed version would not have prevented the birth defects that followed its 1950s use. Ibuprofen's two forms differ sharply in effect, but the body quietly converts the inactive one into the active one, which is why the mixed pill works anyway; L-DOPA, by contrast, crosses into the brain where dopamine itself cannot, and remains central to Parkinson's treatment decades after Oliver Sacks's patients briefly awakened.

The full dispatch is available from the source below.