The complexity of adverse side-effects to biological agents.

Whereas adverse effects induced by xenobiotics are mainly linked to the pharmacological effect, the adverse side-effects induced by biological agents (BA) are often target-related and linked to the biological consequences of their action. Based on these differences, an original classification of the adverse effects has been proposed. Five types of adverse effects induced by BA are described (α, β, γ, δ, and ε). This classification provides a very useful scheme for a better understanding of these adverse effects. This approach should help to better characterize the pathogenic mechanisms involved and to optimize their management. Healthcare professionals should be aware of the specific risks related to this relatively new class of drugs. Close monitoring of these BA is therefore recommended.