Table 3.

Some of the functions describing the relationship between in vivo and in vitro drug dissolution.

Description	Function
Identity	F2(θ2, t) = F1(θ1, t)
Linear	F2(θ2, t) = θ51 + θ52F1(θ1, t)
Sigmoid	$F_2({\theta }_2,t)={\theta }_{51}+\frac{{\theta }_{52}{F}_1{({\theta }_1,t)}^{{\theta }_{53}}}{{\theta }_{54}+F_1{({\theta }_1,t)}^{{\theta }_{53}}}$
Higuchi	F2(θ2, t) = (θ51F1(θ1, t))0.5
Hixon-Crowell	$F_2({\theta }_2,t)={\theta }_{51}-{({\theta }_{51}^{0.33}-{\theta }_{52}{F}_1({\theta }_1,t))}^3$
Weibull	F2(θ2, t) = θ51 − θ52e(−θ53(F1(θ1,t))θ54

θ_5i (i = 1, 2, 3, 4): parameter θ₅ (see equation 10) at observation times t₁, t₂, t₃, t₄.