Figure 5.
Molecular structures and allergenicity. Immunogenicity is attributable to medications having a phenyl ring with a para-amine substitution. This is found in sulfonamide antibiotics and compounds containing para-aminobenzoic acid (PABA) such as certain sunscreens and cosmetics. It is also found in methylparaben preservatives and ester local anesthetics such as procaine. Ester linkages (procaine) or side chains (articaine) are not immunogenic, nor is the sulfur atom of a thiophene ring (articaine). * indicates immunogenic moiety.