There a number of factors that can relate to how the medicine is absorbed by the body, how it gets to the cells it needs, how it’s changed by the body (if at all), and how it’s removed from the body. Certain formulations are made for extended release, or get bound by proteins or stored in fat to last longer. Some medications just naturally have a longer half life. Some medications interact with other medications/supplements/alcohol by affecting how fast they get changed by the liver.
Latest Answers