Table 1.

Descriptive equations and population variability for anatomical, physiological, and biological parameters necessary to inform a physiologically based pharmacokinetic model

Parameter	Unit	Descriptive equation	CV (%)
BMI	kg/m2	$\text{Random}\text{uniform}\text{distribution}$
FFMI	kg/m2	$30.86-3.09\times \text{Sex}-0.13\times \text{Body}\text{height}+0.14\times \text{Body}\text{weight}$	8.58
FMI	kg/m2	$\text{FFMI}-\text{BMI}$
Body height	cm	$-0.0039\times {\text{Age}}^2+0.238\times \text{Age}-12.5\times \text{Sex}+176$	3.8
Body weight	kg	$\text{BMI}\times {\left(\text{Body}\text{height}/100\right)}^2$
Lungs weight	kg	$-2.16+0.02\times \text{Body}\text{height}$	18.38
Adipose weight	kg	$\text{FMI}\times {\left(\text{Body}\text{height}/100\right)}^2$
Lean body weight	kg	$\text{Body}\text{weight}-\text{Adipose}\text{weight}$
Bone weight	kg	$-9.5+0.1\times \text{Body}\text{height}+0.03\times \text{Body}\text{weight}-0.023\times \text{Adipose}\text{weight}\text{precentage}$	5.78
Brain weight	kg	${\text{e}}^{\left(-0.00075\times \text{Age}+0.0078\times \text{Body}\text{height}-0.97\right)}$	9
Gonads weight	kg	$0.039-0.028\times \text{Sex}$	17.78
Heart weight	kg	$0.037+0.0012\times \text{Age}+0.0049\times \text{Lean}\text{body}\text{weight}$	9.32
Kidneys weight	kg	$-0.11-0.48\times \text{Sex}+0.003\times \text{Age}+0.18\times \text{BSA}$	13.15
Muscle weight	kg	$1.4-1.53\times \text{Sex}-0.051\times \text{Age}+0.5\times \text{Lean}\text{body}\text{weight}$	2.96
Skin weight	kg	$\text{BSA}\times \left(2.07-0.11\times \text{Sex}\right)\times 1.05$	13.37
Thymus weight	kg	$0.0027+0.0002\times \text{Body}\text{weight}$	32.64
Stomach weight	kg	$0.257$	22.5
SIL	cm	$\frac{136.86-8.09\times \text{Sex}+0.87\times \text{Age}+2.93\times \text{Body}\text{height}+0.29\times \text{Body}\text{weight}-91.2}{1.09}$	17.7
Jejunum weight	kg	$\frac{\text{SIL}\times 0.4\times \pi \times 2.43\times 0.15\times 1.04}{1000}$
Ileum weight	kg	$\frac{\text{SIL}\times 0.6\times \pi \times 1.92\times 0.15\times 1.04}{1000}$
Duodenum weight	kg	$\left(\text{Jejunum}\text{weight}+\text{Ileum}\text{weight}\right)\times \frac{0.042}{0.958}$
LIL	cm	$0.52\times \text{Body}\text{height}+18.5$	11.26
Large intestine weight	kg	$\frac{\text{LIL}\times \pi \times 4\times 0.25\times 1.04}{1000}$
Gut weight	kg	$\text{Stomach}\text{weight}+\text{Jejunum}\text{weight}+\text{Ileum}\text{weight}+\text{Duodenum}\text{weight}+\text{Large}\text{intestine}\text{weight}$
Spleen weight	kg	${\text{e}}^{\left(-3.46-0.017\times \text{Sex}+0.93\times \text{BSA}\right)}$	36.71
Pancreas weight	kg	$0.089-0.02\times \text{Sex}+0.0023\times \text{BMI}$	23.27
Liver weight	kg	$0.36+0.023\times \text{Lean}\text{body}\text{weight}+0.01\times \text{Adipose}\text{weight}$	17.49
Blood weight	kg	$2.58+0.057\times \text{Body}\text{weight}-0.061\times \text{Adipose}\text{weight}\text{percentage}$	9.08
HR	Beats/min	$\text{Truncated}\text{normal}\text{distribution},\text{mu}=80,\text{sigma}=13.2,\text{min}=60,\text{max}=100$
EDV	mL/beat	$43.13+12.96\times \text{Blood}\text{weight}$	8.05
EF	–	$0.65-0.0018\times \text{BMI}$
CO	L/min	$\text{HR}\times \text{EDV}\times \text{EF}/1000$
Adipose blood flow	% of CO	${\text{exp}}^{\left(2.50-0.043\times \text{BMI}+0.033\times \text{Adipose}\text{weight}\right)}$
Bone blood flow	% of CO	$5$
Brain blood flow	% of CO	$\text{BMI}<25=12\text{and}\text{BMI}\ge 25=12-0.13\times \left(\text{BMI}-25\right)$
Gonads blood flow	% of CO	$-0.03\times \text{Sex}+0.05$
Heart blood flow	% of CO	$3.41+0.29\times \text{Sex}+0.11\times \text{BMI}$
Kidneys blood flow	% of CO	$20.57-1.76\times \text{Sex}$
Muscle blood flow	% of CO	${\text{e}}^{\left(3.01-0.22\times \text{Sex}-0.012\times \text{BMI}\right)}$
Skin blood flow	% of CO	$5.68-0.034\times \text{BMI}$
Thymus blood flow	% of CO	$1.5$
Gut blood flow	% of CO	$\left(18.52+3.04\times \text{Sex}\right)-\left(0.20+0.06\times \text{Sex}\right)\times \text{BMI}+\left(0.0009+0.0004\times \text{Sex}\right)\times {\text{BMI}}^2$
Spleen blood flow	% of CO	$3$
Pancreas blood flow	% of CO	$5.18-0.95\times \text{BSA}$
Liver blood flow	% of CO	$25.53+1.30\times \text{Sex}$
Albumin	g/L	$47.58-0.16\times \text{BMI}$	7.2
AAG	g/L	$0.48+0.012\times \text{BMI}$	25.39
Haematocrit	–	$0.45-0.04\times \text{Sex}$	6.8
GFR	mL/min	$13.02-0.51\times \text{Age}+0.93\times \text{Adipose}\text{weight}\text{percentage}+93.56\times \text{Kidneys}\text{blood}\text{flow}$	0

Blood flows are relative to cardiac output. Virtual individuals with a BMI ranging from 18.5 to 60 kg/m² can be generated

AAG α1-acid glycoprotein, BMI body mass index, BSA body surface area, CO cardiac output, CV coefficient of variation, EDV end diastolic volume, EF ejection fraction, FFMI fat-free mass index, FMI fat mass index, GFR glomerular filtration rate, HR heart rate, LIL large intestine length, Sex 0 = male, 1 = female, SIL small intestine length