[Drug interchangeability: clinical approach and consumer's point of view].

The rational construction of an essential drug list, considering the patient's need, drug safety, availability and the best cost-benefit ratio, is based on drug safety, efficacy and quality. However, in daily practice, the prescriber's decision is mostly influenced by drug effectiveness, following criteria that increase adherence to the treatment, such as relative drug toxicity, convenience, cost and prescriber's experience. In addition, frequent launching of new molecules for the same therapeutic indication, together with wide publicity targeting prescribers, interferes with the decision-making process. Similarly, the bonuses offered by the industry for over-the-counter drug sales interfere with the consumer's choice. The confrontation between known human biological variability and the knowledge that there is no absolute similarity between drugs of the same therapeutic class, or even generic drugs, has an impact on the prescriber's drug list, which should include the concept of first and second choice drugs. Prescribers' unfamiliarity with these subjects is a determinant factor for irrational drug use: a public health issue. The objective of this study was to introduce to drug prescribers information that can help them building up a rational drug list for their patients, based on the National Health Surveillance Agency (Anvisa) experience of drug regulation.