My Granddaughter Is Taking 40 Mg Strattera A Day And

my granddaughter is taking 40 mg strattera a day and it wears off around 3 pm daily its in a capsule is it safe for her to take another 40 mg strattera once in the morning and another at 3:30 to go all day she is 5 years old its working till 3 and i dont want to change her to a stimulant for adhd when it works well till then