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If two compounds are biosimilar, it means they are highly unlikely to have clinically meaningful differences between the biosimilar and the reference product (biologic). The two molecules may exert minor differences, but their effects are nearly identical, although never 100%. Biosimilarity is more encompassing than bioequivalence because it also includes the clinical effects and not only the pharmacokinetic (PK) and pharmacodynamic (PD) aspects. On the other hand, bioequivalence means there is no significant difference in the rate and extent to which an active ingredient or compound in pharmaceutical equivalents or alternatives becomes available in the body when administered in the same dose under appropriate study conditions.¹ Biosimilarity and bioequivalence are similar, but not identical.

Much like consuming any substance can be believed to be beneficial for one’s health even if it is not (placebo), something harmless can be harmful when we have biased beliefs that it is harmful. This is the nocebo effect. These are the non-specific effects of a treatment that can be harmful for one’s health. Common symptoms from a nocebo effect can include drowsiness, nausea, fatigue, and insomnia. We can think of it like a placebo effect, but having negative consequences for patients’ health. The nocebo effect can be directly related to patient and/or physician beliefs about a treatment or condition itself in the absence of a sham control. Having awareness and understanding is the key for healthcare professionals to effectively minimize the nocebo effect/ response in patients being treated with biosimilars.