On the other hand, if the half-life is long (eg
oxycontin, which slowly releases the
drug into the body, rather than almost all at once like
oxycodone),
then a substantial fraction of the active form of the drug may be in the system at the time of the next dose. It can be shown that eventually an almost steady state concentration is reached. This means that after a few weeks a person may have a reasonable concentration of the active form of the drug in their body, 24 hours a day.