The main VAS values is significantly lower in theophylline group in comparison with the acetaminophen group at 2 ( 5 + / - 1.57 vs. 5.97 + / - 1.27 ) , 6 ( 3.43 + / - 1.73 vs. 4.33 + / - 1.49 ) , and 12 ( 2.67 + / - 2.35 vs. 4.24 + / - 1.97 ) hours after drug administration ( p < 0.05 ) .