I will be interested in that answer myself and will ask the next time we see our endo. My 5yr old son gets his last dose no earlier than 7:30 and no later than 11:00pm. During his first year of life he rec'd it at 11:00pm however, after discussions on our part the doctor agreed to give it at bed time. So for us it is typically administerd 7:30-8:00pm. I won't get into all the reasons why we wanted it changed to earlier, the doctor was hesitant but agreed to try and she checked his blood work monthly for about 6months. He showed no signs of anything from the change so she has allowed it to continue. When I get an answer I will post. Judy