title: Theorem on the apparent volume of distribution and the amount of drug in the body at steady state.
abstract: For an N-compartmental system, with irreversible drug loss from the sampled compartment, the equilibrium concentration, C (infinity), obtained with a zero-order drug input is related to the total amount of drug in the system, T, by C (infinity) V = T. The scalar V is the volume of distribution of the corresponding closed system. The moment functions of the open system define V, and hence T is directly calculable. The derivation is general in the sense that the topology of the system is not specified and no functional form for C (t) is required.
mesh_terms: D006801:Humans; D008433:Mathematics; D008954:Models, Biological; D004364:Pharmaceutical Preparations / Q000378:metabolism*
chemical_list: D004364:Pharmaceutical Preparations