Table 3.

Some of the functions that have been used to describe in vitro drug dissolution.

Description	Function
Exponential	F1 (θ1, t) = 1 − e (−θ11t)
Weibull	F1 (θ1, t) = 1 − e (−θ11tθ12)
Higuchi	F1 (θ1, t) = kH (t)0.5
Logistic	$F_1({\theta }_1,t)=\frac{e^{({\theta }_{11}+{\theta }_{12}\mathit{log}(t))}}{1+e^{({\theta }_{11}+{\theta }_{12}\mathit{log}(t))}}$
Korsmeyer-Peppas	$\frac{M_t}{M_{\infty }}=k{t}^n$

θ_1i (i = 1 and 2): parameter θ₁ at observation times t₁ and t₂; k_H: the Higuchi dissolution constant; M_t: the amount of drug released at time t; M_∞: the amount of drug released at infinite time; M_∞: the kinetic constant; n: the release exponent.