Medical Writing. An unequivocal commitment to the sustainability of the healthcare system, always making it clear that the responsibility for the prescription –always by trademark, not by active ingredient- lies with the clinician. The substitution of reference drugs as an act at an administrative level is highly reprehensible, and the exchange within a treatment that has already begun must be a decision of the doctor discussed with the patient. The extrapolation of indications should not do by definition. Perfect traceability must be ensured to guarantee correct pharmacovigilance.