Longcirculatieparameters

Longcirculatieparameters is a term used in Dutch-language literature to refer to the set of parameters that describe the persistence and dynamics of substances, signals, or items in circulation over extended time scales. In pharmacokinetics, they describe how a drug remains in systemic circulation before being eliminated or redistributed. In engineering and ecology, they can denote rates that govern exchange between circulating compartments or populations.

Core parameters typically include the elimination rate constant (kel) or clearance (CL), the volume of distribution (Vd), and the mean residence time (MRT), along with inter-compartment transfer rates (k12, k21) that determine long-term circulation. The long half-life (t1/2) is a key indicator. The exact set depends on the chosen model (one-, two-, or multi-compartment).

Estimation is based on concentration-time data, using noncompartmental analysis or compartmental modeling, often within nonlinear mixed-effects frameworks to capture variability. Sufficient late-time sampling is important to characterize slow elimination and long residence times.

Applications include informing dosing regimens for long-acting therapies, predicting steady-state concentrations, and assessing risk of accumulation, as well as modeling persistent circulating signals in ecological or epidemiological contexts.

Limitations: parameter estimates can be sensitive to model structure and data quality; identifiability challenges may arise with sparse data.

See also: pharmacokinetics, compartmental models, half-life, clearance, mean residence time.