Generic - equivalent drugs use in internal and general medicine patients: distrust, confusion, lack of certainties or of knowledge? Part 2. Misconceptions, doubts and critical aspects when using generic drugs in the real world

A lot of issues have been raised to argue that equivalent drugs may not work as well or at least the same as what the drug industry likes to call innovator products. Many doubts and biases are also reported in connection with the use of generic drugs. Doctors are mostly concerned about their efficacy, their tolerability, the quality and amount of active ingredients, their formulation or excipients, their packaging, their pharmaceutical form and their palatability. We describe the differences between prescribability (equivalence when prescribing a drug to a patient for the first time) and switchability (interchangeability of drugs for a patient already in treatment) considering the notions of average bioequivalence, population bioequivalence and individual bioequivalence as well as the usefulness of the U.S. Orange Book in the assessment of bioequivalence. Other key issues deserve attention, such as: duplicate applications for medicinal products, different salt forms, formulations used in the development of each medicinal product and excipients, product quality. Clinicians in collaboration with pharmacists and research pharmacologists have to find solutions for unanswered questions and unsolved doubts, by developing targeted studies, communication tools and shared guidelines.