Displaying 2 results of Alcaftadine Stable Isotopes Alcaftadine is a medication used to treat itchy eyes caused by allergies. Stable isotopes of alcaftadine are non-radioactive isotopes that have the same number of protons and electrons as the original element but a different number of neutrons. These isotopes are useful in research and drug development as they allow for the tracking of the molecule in biological systems without altering its chemical properties.