We also have not seen any side effects or rebound from the guanfacine.
Although the med has a 12-18 hour half life, the effectiveness for ADHD symptoms is only supposed to be about 6-8 hours (per my kid's doc). Peak plasma concentration is between 1-4 hours. It works longer with higher dose within limits (keeping the blood level within therapeutic range for a longer period), and you have to watch for the side effects of too high of a dose.
My daugter takes 2mg AM and 2mg at night with a 1/2mg booster in the afternoon for socially challenging activities.
There is some info on the Ask Dr Jones site:
http://www.askdrjones.com/search/guanfacine
And the phamacokinitecs section of the package insert:
http://www.parpharm.com/pdf/product/guanfacine_po.pdf
We're still relatively new to guanfacine, and I have three questions at this time:
1. I know stimulant meds tend to last longer when you use a higher dose. Is the same true of guanfacine?
2. Has anyone experienced rebound as the guanfacine wears off? I gave my child the guanfacine at 10 AM this morning, and he had a difficult 1/2 hour at around 4:30 PM, but then was fine until stimulant wore off at 6:30 PM. I'll have to watch this, but I'm wondering if anyone experiences rebound issues with guanfacine or if that issue is limited to stimulant medications.
3. When talking w/ the dr. today, he asked if my child was waking up overnight. The question surprised me because actually he has been recently, but I didn't connect it to his recently starting guanfacine. The dr. said that this can be a side effect for some people, and we'll have to watch it to see if it's an adjustment issue or an ongoing side effect. Has anybody else experienced this? If so, is there anything we can do to prevent it? My child hasn't had a problem sleeping through the night in a very long time. His problem used to be falling asleep due to hyperactivity, but once he was asleep, he used to sleep through the night. Is there now an issue when the guanfacine wears off overnight? Is that why he's waking up? Like I said, waking up overnight never was a problem before starting a stimulant medication, or when taking only a stimulant medication (prior to guanfacine), or when he took melatonin to help fall asleep.
As always, thanks for the help. I love this board!
We never saw the "rebound" or night waking, but the first couple of weeks my daughter would "crash" (fall asleep) in the middle of the day. About 7-8 hours after taking the Guanfacine. We stopped taking stimulants at the same time so I do not know if it was that or the Guanfacine, or both. It seems to have resolved. I do not notice any side effects from the Guanfacine and we get side effects from everything.