DESCRIPTION:
MM approximation to two compartment TMDD model 


[LONGITUDINAL]
input = {kel, kep, kon, kout, koff, ktp, kpt, Vc, R0}

PK:
; Dosemg: Dose injected into central compartment (mg/kg)
; MWlig=150000; molecular weight of ligand (Da) 
; (Dosemg*1e-3/MWlig)*1e9 ; Dose conversion (nmol/kg)

depot(target=Lc, p=100/15/Vc)  ; Lc is a concentration (nM)

EQUATION:
odeType = stiff

Km=(kep+koff)/kon ; Michaelis constant (nM)
kin = kout*R0     ; Synthesis of receptor (nM/day)

;Initial Conditions
Rtot_0 = R0

;Ordinary Differential Equations
Vmax = Rtot*kep
ddt_Lc = -(kel+kpt)*Lc-(Vmax*Lc)/(Km+Lc)+ktp*Lt
ddt_Rtot = kin-kout*Rtot-(kep-kout)*(Rtot*Lc)/(Km+Lc)
ddt_Lt   = -ktp*Lt + kpt*Lc


