effective half life

For a @R05077@ substance, the time required for the amount of that substance in a biological system to be reduced to one half of its value by both @R05083@ and biological processes, when the rate of removal is approximately exponential.
PAC, 1994, 66, 2513. (Nomenclature for radioanalytical chemistry (IUPAC Recommendations 1994)) on page 2520 [Terms] [Paper]