DESCRIPTION: 
 - PK  one compartment model defined using pkmodel 
 - PD  turnover model with inhibition on the input

[LONGITUDINAL]
input =  {Tlag, ka, V, Cl, Imax, IC50, Rin, kout}

EQUATION:
Cc = pkmodel(Tlag, ka, V, Cl)
E_0 = Rin/kout
ddt_E = Rin*(1-Imax*Cc/(Cc+IC50)) - kout*E

