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Table 5 Parameters and units of drug transport across the brain barriers. The physiological range of values of the parameters is given for rat and human, based on references from the literature

From: The need for mathematical modelling of spatial drug distribution within the brain

Parameter Value (rat) Value (human)
P, BBB passive permeability (m s−1) 10–10–10−5 [17] 6 × 10−8–10−6 [227]
kBBB, BBB rate constant (s−1) 3.5 × 10−5–1.17 × 10−3 [128, 134, 135] 1.4 × 10−4–1.4 × 10−2 [132]
CLBBB, BBB transfer clearance (10−5 L s−1) 0.15–8.5 [143] 113–850 [227]
Ptrans, BBB transcellular permeability (10−7 m s−1) 10−3–102 [17] 0.6–10 [227]
Dpara, BBB paracellular diffusivity (10−12 m2 s−1) 467–767 [143] 550–767 [227]
WTJ, width tight junction (10−6 m) 0.3–0.5 [143, 228] 0.3–0.5 [227, 228]
Tm, active transporter velocity 10−5−10−8\(\upmu\)mol s−1 [229] 22–167 \(\upmu\)mol L−1 s−1 [111]
Km, concentration to reach half of Tm (103 \(\upmu\)mol L−1) 10−2−101 [230] 4.5–5 [111]
Surface area BBB (m2) 150 × 10−4–263 × 10−4 [231,232,233] 12–18 [2, 17]
Surface area BCSFB (m2) 25 × 10−4–75 × 10−4 [232,233,234] 6–9 [17]