********** MODEL NAME
model_1cpt_linear_abs1_racemix_mixture_2_enantiomers_and_metabolites

********** MODEL NOTES

PK model for simulation of drug concentration in central compartment
with following characteristics:
Compartments:  6 gut, liver, rr, ss, metrr and metss
Elimination :  linear
Absorption  :  first order (with lag time)

Unit convention
Dose: mg
Concentration: ug/mL
Time: hours

The annotation of the parameter units is consistent with the given unit convention.
Units of the inputs (dose) and outputs (concentration) in the dataset for parameter estimation need to match the unit convention.

********** MODEL STATES
d/dt(Ad)    = -K12*Ad + Fabs1*INPUT1
d/dt(Liver) =  K12*Ad - K23*Liver - K24*Liver - K25*Liver - K26*Liver + K32*RR - K42*SS
d/dt(RR) =              K23*Liver                                     - K32*RR - K30*RR
d/dt(SS) =                          K24*Liver                                  - K42*SS - K40*SS
d/dt(RRmet) =                                   K25*Liver - K50*RRmet
d/dt(SSmet) =                                               K26*Liver - K60*SSmet

Ad(0) 	 	= 0
Liver(0)    	= 0

********** MODEL PARAMETERS
Fabs1    	  = 1    # Relative bioavailability (fraction)
K12               = 1.4  # Absorption rate parameter (1/hour)
Tlag1             = 0    # Absorption lag time (hours)
CLRR              = 7 	 # Apparent clearance RR (L/hour)
VcRR 	          = 35 	 # Apparent central volume RR (L)
K23               = 0.4  # Transfer liver to RR
K32               = 0.2  # Transfer RR to liver
CLSS              = 5 	 # Apparent clearance SS (L/hour)
VcSS 	          = 3.4  # Apparent central volume SS (L)
K24               = 0.7  # Transfer liver to SS
K42               = 0.5  # Transfer SS to liver
K25               = 0.3  # Transfer liver to metabolite RR
CLRRmet           = 5.32 # Apparent clearance metabolite RR (L/hour)
K26               = 0.2  # Transfer liver to metabolite SS
CLSSmet           = 3.2  # Apparent clearance metabolite SS (L/hour)

********** MODEL VARIABLES

% Calculation of concentration in central compartment
Cc    = Liver

VcRRmet = VcRR # AVOID IDENTIFIABILITY ISSUES
VcSSmet = VcSS # AVOID IDENTIFIABILITY ISSUES
K30 = CLRR/VcRR
K40 = CLSS/VcSS
K50 = CLRRmet/VcRRmet
K60 = CLSSmet/VcSSmet


% Defining an output (only needed when interfacing with NLME
% parameter estimation tools such as NONMEM and MONOLIX)
OUTPUT1  	  = Cc  # Compound concentration in Liver (ug/mL)

********** MODEL REACTIONS


********** MODEL FUNCTIONS


********** MODEL EVENTS