Table 1.

Independent variables and responses used in the Box–Behnken design for the formulation and optimization of AVA PLGA NPs.

Independent Variables	Levels
	(−1)	(0)	(+1)
X1: AVA:PLGA (w/w)	1:1	1:3	1:5
X2: Sonication time (min)	2	4	6
X3: PVA concentration (%)	0.50	1.75	3.00
Responses	Desirability constraints
Y1: Particle size (nm)	Minimize
Y2: EE (%)	Maximize

Abbreviations: AVA, avanafil; PLGA, poly (lactic-co-glycolic acid); PVA, polyvinyl alcohol.