Efficacy should always be the first criterion, but, in reality, cost is often the driving factor in the selection process. Formulary decision makers make their selections on the basis of which drugs are considered to be the best treatment for most people and the least costly alternative. People are different, and patients with the same condition may react differently to the same drug. In closed formularies, the physician loses the ability to choose the drug he or she feels best fits the needs of each patient. The plan should have a process by which the treating physician may provide patients with non-formulary drugs when deemed medically necessary.
Some patients are on complex regimens of numerous drugs.
Similar drugs can have different effects and a change in only one prescription can result in adverse health consequences. The plan should keep patients and their physicians updated on changes in the formulary lists. Some plans provide physicians with a monthly drug budget, financially penalizing them if they go over budget and rewarding them if they stay below budget. This is commonly referred to as pharmacy risk sharing. Advocates claim that these programs give physicians an incentive to consider the cost effectiveness of the drugs they prescribe.