That would be about right as well for dosage if you are just estimating.
Because you take the weight in pounds and divide it by 2.2 (which is basically dividing it in half) to get kilo's then multiplying it again
by 2mg to get the lower end of the dosage - so really you are back to about your original weight.
But if you want to know the high end of the acceptable dosage than this is helpful...otherwise you can just go with saying that its 25mg=25lbs
I just wanted to give a range on dosage because in case of emergency you might need a higher inital dose.