15yo gay friend has "Bipolar 1 Depression" w/ Schizophrenia & ADHD. Isn't 400mg of Seroquel daily too much?

I would be more concerned about him stopping the meds cold turkey then the dose of Seroquel he is taking. 400mg a day is close to half the maximum dosage (can't remember if it is 1000mg or 1200mg). The amount a person is taking does not dictate the severity of the disorder as people respond differently to medication. I take 400mg a day and chances are it will increase but this has more to my body adapting to the med then the actual illness at work