takes about 3-5 days from system to clear.
It can definitely show in the urine if you have consumed within 5 days of your urine test.
Although it is not a amphetamine but it structurally and chemically close to it and can give false positive for amphetamines
Take plenty of water and drink few cups of coffee.
However the best would be to show the prescription so that authorities are convinced that you have not consumed any amphetamine and are taking duromine under medical advice