The Global. The interchangeability and substitution between biological medicines continues to provoke intense debates between detractors and defenders of each of the positions. The Administration recognizes its great clinical work but admits that prioritization strategies are needed due to its high costs. On the other hand, the specialized jurists of the Health Law Association are clear that the Law on Guarantees provides enough material to prevent the substitution or interchangeability of these drugs unless the decision is made by the doctor.