I wrote about this once before, my Dad has been off BP meds for months now due to Niacin. His intake is 1-2 caps of Niacin (as inositol hexanicotinate 625mg) 500 mg.
But for me there are other reasons to take large amounts and one of those is to disallow bio-reserves like Babesia to hide out, Lyme Beyond Antibiotics suggest 3-4g of Niacin per day...