Differences in antibody responses of intradermal and intramuscular injections of botulinum toxin type A

Abstract

Abstract Botulinum toxin type A (BoNT/A) has been used for medical purposes for decades. Approximately 3% of long-term patients do not respond to treatment, which might result from antibody formation. This study aimed to compare the antibody levels in patients receiving intradermal and intramuscular toxin injections of several types of BoNT/A. One hundred twenty subjects were divided into groups receiving either intradermal or intramuscular injections. Each group was equally divided into 6 subgroups receiving one of the 6 types of BoNT/A (incobotulinumtoxinA, onabotulinumtoxinA, abobotulinumtoxinA, letibotulinumtoxinA1, letibotulinumtoxinA2, and prabotulinumtoxinA). Blood was drawn from each subject, and enzyme-linked immunosorbent assays (ELISA) were used to detect total human immunoglobulin G (hIgG) specific to the whole molecule of BoNT/A, hIgG against active sites and complexing proteins of BoNT/A. Intradermal injection induced higher levels of BoNT/A specific hIgG than the intramuscular injection did for every type of BoNT/A except for letibotulinumtoxinA. The level of hIgG against active sites of BoNT/A increased after the injections and peaked at day 30 before gradually decreasing. The levels of hIgG specific to complexing proteins did not change significantly over the course of the study. However, the levels of hIgG specific to either active sites or complexing proteins were lower than cut-off points in BoNT/A treatment responders. In summary, our finding suggested that intramuscular BoNT/A injections could be preferable for facial treatment, with retreatment after 90 days of treatment to minimize antibody production.