Table 2.

The kinetics models used to fit the release data

Kinetics model	Equation	Coefficient of determination (R2)
		pH 4.4	pH 5.4	pH 6.4	pH 7.4
Zero order	F=k0t	0.777	0.788	0.762	0.728
First order	Ln(1−F) = −kf t	0.901	0.922	0.915	0.945
Higuchi	$F=k_H\sqrt{t}$	0.918	0.926	0.910	0.884
Power law	LnF = Lnkp + pLnt	0.927	0.933	0.915	0.910
Square root of mass	$1-\sqrt{1-F}=k_{1/2}t$	0.652	0.650	0.608	0.520
Hixson–Crowell	$1-\sqrt[3]{1-F}=k_{1/3}t$	0.805	0.820	0.799	0.796
Three seconds root of mass	$1-\sqrt[3]{{(1-F)}^2}=k_{2/3}t$	0.710	0.723	0.693	0.663
Weibull	Ln[−Ln(1−F)] = −βLn td + βLn t	0.961	0.970	0.960	0.974
Linear probability	Z = Z0 +qt	0.778	0.790	0.763	0.727
Wagner log-probability	Z′ = Z′0 +q′Lnt	0.997	0.998	0.997	0.993

Notes: Parameters of models were obtained by linear regression. F represents fraction of drug released up to time t. The k₀, k_f, k_H, p, k_P, k_1/3,k_1/2, k_2/3, t_d, β, Z₀, Z′₀, q, and q′ are parameters of the models. Z and Z′ denote probits of fraction of drug released at any time. Ln: natural logarithm.