New excluded drugs lists devised by pharmacy benefits managers are raising the hurdle for reimbursement of drugs the PBMs' pharmacy and therapeutics committees consider to be clinically equivalent to cheaper drugs. Drugs that are not sufficiently differentiated will not receive low reimbursement - they will receive none at all.

PBMs have always made decisions about what drugs will be included in formularies with higher cost-sharing and which will be available with lower cost-sharing. But excluded drugs lists take this one step further by not providing any cost-sharing for some drugs.