tokens: The 50 % effective dose of d - tubocurarine ( microg / kg ) in the tibialis muscle was smaller in the P10 ( 33 . 6 + / - 5 . 4 ) than in the S ( 61 . 9 + / - 5 . 0 ) or the P100 ( 71 . 3 + / - 9 . 6 ) groups .