Table 1.

Fitting curve by different mathematical model under different pH values (Rt: accumulated release rate).

	pH=5.5		pH=7.2
	Equation	r2	Equation	r2
zero-order	Rt = 0.0047 t + 0.2433	0.811	Rt = 0.0039t + 0.1298	0.850
First-order	Ln(1-Rt) = -0.0118 t - 0.2627	0.944	Ln(1-Rt) = - 0.0065t - 0.1379	0.897
Higuchi	Rt = 0.0679 t1/2 +0.0874	0.952	Rt= 0.055t1/2 + 0.0079	0.963
Weibull	lnln[1/(1-Rt)] = 0.6384lnt - 2.4694	0.977	lnln[1/(1-Rt)] = 0.653lnt - 3.1688	0.987
Ritger-Peppas	ln (Rt/R∞) = 0.4862lnt - 2.4274	0.933	ln (Rt/R∞) = 0.5608lnt - 3.1287	0.981