Optimized chronomodulated dual release bilayer tablets of fexofenadine and montelukast: quality by design, development, and in vitro evaluation

Future Journal of Pharmaceutical Sciences

Table 1 Variables and their levels in Box-Behnken design for immediate and sustained release tablet layers

Immediate release fexofenadine HCl tablet layer
	Levels
	− 1 (low)	0 (medium)	+ 1 (high)
Independent variables
A = fexofenadine HCl (mg)	60	90	120
B = sodium starch glycolate (mg)	5	12.5	20
C = sodium bicarbonate	10	15	20
Dependent variables
Constraints
Y₁ = drug release (%)	Maximize
Y₂ = disintegration time (seconds)	Minimize
Sustained release montelukast sodium tablet layer
	Levels
	− 1 (low)	0 (medium)	+ 1 (high)
Independent variables
A = montelukast sodium (mg)	5	7.5	10
B = HPMC (mg)	15	30	45
C = magnesium stearate	2	3	4
Dependent variables
Constraints
Y = drug release (%)	Maximize