Displaying 1 results of Levonorgestrel Stable Isotopes Levonorgestrel is a synthetic hormone used in various contraceptive methods. Stable isotopes of levonorgestrel are non-radioactive forms of the hormone that have the same chemical properties as the natural isotopes. These isotopes are used in research to study the pharmacokinetics and metabolism of levonorgestrel, as well as to develop new contraceptive methods with improved effectiveness and safety.