Modafinil, the active ingredient in Modalert 200, has a half-life of around 12 to 15 hours. It can therefore remain in your system for a number of days, while its benefits on boosting wakefulness normally subside after 12 to 14 hours. For up to three to four days following usage, modafinil may be found in urine, depending on variables such as metabolism, age, liver function, and dose. The body may retain residues of Modalert 200mg for a longer period of time, even when the stimulating effects wear off after a day.