Table 1 The p-i Concept-Pharmacological Interaction With Immune Receptors

A chemically inert drug, unable to covalently bind to proteins, is still able to fit into some of the many immune receptors (as it does into other proteins/receptors). This reversible drug-receptor interaction can, under certain circumstances, activate immune cells specific for peptide antigens, which expand and can cause inflammatory reactions of different types. Such a reaction would not need the generation of one's own immune response to the drug, albeit an expansion of drug-reactive cells may be required before symptoms appear.