PBK model parametrisations from data

To simulate the fate of a substance in a compartment, the PBK models in MCRA are run using different dosing patterns. In general, the length of the simulation period is specified in days.

The Exposure events and dose generation setting specifies how repeated dose patterns are applied.

• Use usual (average) exposures per route to specify a single dose per day, repeated over the entire simulation length. The dose applied is for an acute exposure assessment equal to a daily dose, for a chronic assessment equal to the average of all daily exposures of an individual (e.g. OIM).

• Use (randomly selected) daily exposures per route to specify more complex dosing patterns. The daily exposures (in a chronic context) are randomly allocated to the events, so for one event per day, the entire sequence of doses is a random sequence of the daily doses of one individual and, in case of a two 24hour recall, two different doses are sampled. When the specified number of events is > 1, the daily doses are divided by the specified number of events in a day and randomly allocated to the events. Note that for PBK models with a resolution in hours, the number of events should be equal to 1, 2, 3, 4, 6, 8 and 12.

For irregular dosing patterns use setting Specify event timings. Allowed numbers are 1, 2, 3,…,24 separated by spaces (e.g. 1 2 7 12).

Currently, option Specify event timings is only implemented for the oral route and for PBK models with resolution in hours.