Rotatable Bonds in Drug Design: How Many Is Too Many?

By BioDockify Computational Research Team · September 4, 2026 · Concepts

Rotatable bonds explained: the definition tools actually count, the entropy cost behind the Veber rule of 10, bRo5 territory, and design moves that cut flexibility safely.

Read the complete article with tables, code and references on BioDockify.

Key References

• Veber DF, Johnson SR, Cheng HY, et al. Molecular properties that influence the oral bioavailability of drug candidates. J Med Chem. 2002;45(12):2615-2623. doi:10.1021/jm020017n
• Doak BC, Zheng J, Dobritzsch D, Kihlberg J. How beyond rule of 5 drugs and clinical candidates bind to their targets. J Med Chem. 2016;59(6):2312-2327. doi:10.1021/acs.jmedchem.5b01286
• RDKit documentation: rotatable bond definition via CalcNumRotatableBonds and SMARTS exclusions, rdkit.org.

Scope & Limitations

Rotatable bond count is a static topological descriptor; it cannot see which conformations a molecule actually populates on the binding or permeation timescale