Here, calculation of macro-constants (or hybrid-constants) for compartment models with number of compartments ranging from one to five. The quantities and concentrations of the substance (e.g., drug) in each compartment after time t can be calculated as well. For passive transport, if only intercompartmental clearances are known, the first option allows calculating of the elimination rate constants which are needed in next steps. Algorithms published in own articles were used here. Basic assumption: the transport obeys the rules of first-order kinetics. Symbols used:
Vi: volume of compartment i,
Cti, Qti: concentration / quantity of the substance in compartment i after time t,
C0i, Q0i: initial (t= 0) concentration / quantity in compartment i,
R1: infusion rate into compartment 1, Micro-constants (input data):
kij: elimination rate constant from i to j,
kji: elimination rate constant from j to i,
ki0: elimination rate constant from i to the environment. Macro-constants (hybrid-constants, output data):
bi: exponent rates,
ci, di, etc.: multiplying factors;
When entering the data, one must take care on the conservation of the units.
This algorithm calculates the macro-constants (hybrid constants) from the micro-constants (elimination rate constants) in the two-compartment pharmacokinetic model.