Table 5.

Skin irritation effect of different chemical enhancers.

Chemical enhancer with concentration	Skin irritation
Citric acid (2.5%)	0
Oleic acid (5%)	0
Isopropyl myristate (10%)	0
N-lauroyl sarcosine (2%)	2
Tween-20 (2%)	1
Transcutol (20%)	1
Dimethyl sulfoxide (10%)	2
N-methyl pyrrolidone (10%)	3