You need to take a loading dose of 140mg/Kg of your body weight, after which you can 70mg/Kg every four hours for 17 hours. So in case you weigh 80Kg, you'll want to take an initial dose of 11,200mg accompanied by 5600mg every 4 hours for seventeen total hours.Codeine is really a prodrug metabolized by cytochrome P450 2D6 to morphine which mediates