Formulation and Optimization of Sustained Release Stavudine Microspheres Using Response Surface Methodology

Table 1

 3² full factorial design layout.

Batch code	Variable levels in coded Form		Particle size (μm)*	Drug entrapment efficiency (%)*	𝑡80% (minutes)*
	𝑋1	𝑋2
F1	−1	−1	221	55	283
F2	−1	0	212	49	281
F3	−1	1	206	47	264
F4	0	−1	251	64	284
F5	0	0	245	59	287
F6	0	1	234	57	300
F7	1	−1	290	70	571
F8	1	0	277	67	547
F9	1	1	269	64	456
Translation of coded levels in actual units
Variables level		Low (−1)		Medium (0)	High (+1)
Drug-to-polymer ratio (𝑋1)		1 : 1		1 : 2	1 : 3
Stirring speed (𝑋2) rpm		800		1000	1200

*Average of three determination.