tokens: Simultaneous administration of morphine with metamizol resulted in a markedly antinociceptive potentiation and an increasing of the duration of action after a single ( 298 + / - 7 vs . 139 + / - 36 units area ( ua ) ; P < 0 . 001 ) and repeated administration ( 280 + / - 17 vs . 131 + / - 22 ua ; P < 0 . 001 ) .