A Hindu Sadhu smoking cigarette

Smokers might benefit from new formulations of a drug that eases nicotine withdrawal. Credit: Narayan Maharjan/NurPhoto/Getty

Biochemistry

Made-to-order molecules could nix nicotine cravings

Customized changes to an existing drug could help smokers to quit.

For more than 50 years, smokers in eastern Europe who want to quit the habit have taken a drug called cytisine. Now, precise changes to cytisine molecules have created compounds with similar benefits, but potentially fewer side effects than the original drug.

Nicotine’s addictiveness stems from its affinity for specific receptors in the brain. Cytisine binds the same receptors, reducing a quitter’s craving for nicotine. But the drug also binds a separate type of nicotine receptor, which might explain why it causes side effects such as nausea.

Timothy Gallagher at the University of Bristol, UK, and his colleagues used an iridium catalyst to cleave a chemical bond at a specific location in the cytisine molecule, and then added various molecular structures at that location. These modified cytisines activated only the nicotine receptor linked to addiction.

Nicotine receptors are also involved in a range of neurodegenerative and psychiatric disorders, which the new compounds might alleviate.