Figure 3. Immune response and the persistence of oxycodone specific antibodies.

Male (M) and female (F) Sprague Dawley rats received four IM injections of either alum adjuvant (Group 1; M1 or F1), 1.43 (Group 2; M2 or F2), or 68 (Groups 3 and 4; M3 or F3 and M4 or F4, respectively) μg/animal Oxy(Gly)₄-sKLH vaccine on Days 1, 15, 29, and 43 of the study. A) Oxycodone-specific serum IgG antibody titers were evaluated by ELISA on Day 50 for 10 animals per sex per group. B) Following oxycodone challenge 5 animals per sex from Groups 1 (M1-R or F1-R) and 3 (M3-R or F3-R) were allowed 4 weeks recovery and their oxycodone-specific serum IgG antibody titers were evaluated on Day 87 of the study. Difference in antibodies titers compared to the control from Day 50 (panel A) were analyzed using a Brown-Forsythe and Welch ANOVA with Tukey’s multiple comparison post-hoc test. Recovery Group 3 titers from Day 87 (panel B) were compared to Group 1 titers using a Welch’s t-test. Comparisons between Day 50 and Day 87 titers for Group 3 were made using a paired t-test with the paired Day 50 and Day 87 data from the same animals. Data are presented as mean ± SEM with individual animal responses shown. Statistical symbols (brackets indicate significance between groups): **: p≤0.01, ***: p≤0.001 compared to the gender matched Group 1, ns=not significant compared to gender and group matched Day 50 and Day 87 time points.