The assessment of new medicines is critical to managing a formulary list, which involves adding new medicines and deleting old ones. Drugs should be evaluated and compared on the basis of:
• efficacy, comparative efficacy
• effectiveness, comparative effectiveness
• safety, comparative safety
• cost of use
Efficacy, effectiveness and safety can be evaluated from a critical assessment of the literature. Much of the information may be biased and it is very important that those evaluating new medicines have the necessary skills and time to assess the literature critically. Once efficacy and safety are established, medicines should be compared according to cost of use and, if possible, cost-effectiveness. Drug costs and quality will vary with locality.