Endocrine Abstracts

Background: Antithyroid drugs (ATD) are indicated as first intension in the treatment of Graves’disease (GD). Only two molecules are marketed in Tunisia: Benzylthiouracil (BTU) and Methimazole (MMI). There is still no clear conclusion about the choice of appropriate drug. Our objective was to compare the MMI treatment with the BTU in terms of efficacy and adverse effects (AEs).

Methods: It’s a retrospective study. We studied patients with a first diagnosis of GD, in the department of endocrinology in Farhat Hached hospital in Susah, between Juanuary 2010 and December 2015. Patients were divided into two groups: G1(patients treated with BTU (n=77)) and G2 (patients treated with MMI (n=44)). Percentages of patients with normal serum FT4 and frequency of adverse effects were measured at 3, 6, 12, 18, 24 and 30 months. The rates of remission and relapse after standard duration with ATD treatment (12 to 18 months) were assessed in each group.

Results: Two groups are similar as genre and clinical presentation. ATD-related AEs were more common with MMI (18.2%) than with BTU (10.4%), but with no significant difference. There was no significant difference in the frequency of occurrence of different minor AEs between the two groups. For major AEs, there was one case of agranulocytosis in the MMI group (2.3%) and one case of ANCA vasculitis in each group (1.3% in G1 and 2.3% in G2). The delay between the occurrence of AEs and the onset of ATD treatment the most frequently was at 3 months with a predilection for MMI-treated patients (P=0.02). The decrease in the fT4 rate was significantly greater with the MMI than with the BTU from the 3rd to the 24th month of the follow-up. The percentage of patients who normalized their fT4 levels was also greater with MMI than with BTU, with a statistically significant difference, up to the 18th month of treatment. The outcome after standard duration with ATD treatment was characterized by a higher remission rate with MMI than BTU (58.3% vs. 31.9%, P=0.012). The relapse rate was similar in both groups (14.5% in G1 vs. 11.1% in G2, P=0.76).

Conclusion: MMI seems to be more effective than BTU on fT4 normalization and remission rate of the GD. However, its accountability for the occurrence of more adverse events needs to be more studied by studies with a larger sample size.