The effective half-life is used for a multicompartment drug and is particularly useful when the contribution of the first phase is considerably greater than that of the terminal phase i.e. elimination is faster than distribution. In this case the terminal rate constant will approximate k21 and will not reflect the elimination of the drug. A good example of a drug of this type is gentamycin. This is useful when terminal half-life is not precisely obtained or is not a dominant factor for accumulation. Some may not relate to elimination of drugs.
Any comments are welcome.
Dear all, Would like to expand on what is being discussed. This is the half-life that will determine accumulation with the respective dosing interval. The deeper compartmental half-life may be just an academic curiosity. It has been said that with the advent of more sensitive bioanalytical techniques, the terminal half-life of drugs get longer. Comments would be appreciated.