Pain frequency decreased significantly ( P < 0.01 ) in 22 ( 25.9 % ) , 51 ( 60 % ) , and 66 ( 77.7 % ) patients in the drotaverine group , at the end of 2nd , 3rd , and 4th weeks , respectively , as compared with 8 ( 9.4 % ) , 18 ( 21.2 % ) , and 26 ( 30.6 % ) in the placebo group .