How does formulary tier placement affect patient access?

Tier 1 (generics) typically has $0-15 copays. Tier 2 (preferred brand) runs $25-50. Tier 3 (non-preferred) is $50-100+. Specialty tiers use 25-33% coinsurance. Moving from Tier 2 to Tier 3 reduces prescription volume 40-60% on average. Manufacturers pay substantial rebates to avoid non-preferred placement.