Fig. 1.

Schematic diagram of the structural pharmacokinetic/pharmacodynamic model for somapacitan. The pharmacokinetic model included a dual pathway from absorption compartment [abs] to central compartment [central] through first-order absorption and zero-order absorption through a transit compartment [transit]. The pharmacokinetic/pharmacodynamic model included an indirect response relationship (dashed line) between the central compartment and the insulin-like growth factor-I compartment [IGF-I]. C somapacitan concentration in the central compartment, EC₅₀ somapacitan concentration corresponding to half-maximum stimulation of IGF-I production rate, E_max maximum increase in IGF-I production rate, F bioavailability, IGF-I insulin-like growth factor-I, K₀ zero-order rate constant, K_a linear absorption rate constant, K_in production rate of IGF-I, K_m Michaelis-Menten constant for saturable elimination, K_out first-order turnover of IGF-I, K_tr linear transit rate constant, V volume of distribution, V_max maximum elimination rate