Hi, hope it helps. I know many on that dose. For me, when i was on it a year ago I could not take more than 2 pills ( 25mg ) because I am suseptable highly to TD. It was throwing my neck out.
but I know many on high doses.
300mg of Seroquel is not going to kill you. I have taken 600mg at one time and I am still here :) That is a large jump to go from 100mg up to 300mg. The only thing you might notice more in the beginning is the sedating effect of the medicine - but it eventually goes away as your body adjusts. If you have questions about the medication, be sure to talk to your doctor about them.
As I got better, the dosage of Seroquel was decreased and I am now on 200mg and doing well. Seroquel worked wonders for me and I hope it helps you as well.