The activity of Abobotulinum toxin A solution stored at 4°c and -18°c for 2 weeks in a rat model

One of the most common non-surgical aesthetic procedures is botulinum neurotoxin (BoNT) injections. Botulinum neurotoxin, produced by a bacterium called Clostridium botulinum, blocks the release of acetylcholine at the neuromuscular junction. There are eight different serotypes of this toxin identified, namely A, B, C1, C2, D, E, F, and G, with the serotype Botulinum neurotoxin type A being the most commonly used in clinical practice. This study aims to compare the efficacy of Abobotulinumtoxin A (AboBoNT A) solutions that have been stored in a refrigerator or freezer for a period of two weeks with freshly prepared solution. The study used male Sprague-Dawley rats weighing between 270 and 330 grams for a minimum of 12 weeks. They were divided into three groups: 2 experimental groups and 1 control group, with 6 subjects in each group. A total of 18 rats were used, with 6 rats in each group. The subjects in each group were painted and numbered within pre-determined areas. The first group received freshly prepared Abobotulinumtoxin A (AboBoNT A) solution, the second group received AboBoNT A solution that had been stored at +4°C for 2 weeks, and the third group received AboBoNT A solution that had been stored at -18°C for 2 weeks. The injection of AboBoNT A solution was administered to the tail muscles of the rats at four points, following the protocol determined in a previous pilot study. A total of 10 U of AboBoNT A was injected, with 2.5 U administered to each of the four designated points. All angular evaluations were recorded by a neutral third party. In the evaluations, KDA was assessed as follows: a negative evaluation for positions with KDA >90°, a positive evaluation of 1 for positions with KDA between 60° and 89°, a positive evaluation of 2 for positions with KDA between 30° and 59°, and a positive evaluation of 3 for positions with KDA <30°. The evaluations were continued from the first positive result until two consecutive negative results were observed. The analysis revealed significant differences in terms of effect intensity among the groups (p=0.003). These differences were found to be statistically significant in terms of effect intensity between Group 1 and Group 2 (p=0.005), as well as between Group 2 and Group 3 (p=0.010). However, no statistically significant difference was observed between Group 1 and Group 3. There was no statistically significant difference among the groups regarding the days of maximum effect (p=0.287). However, there was a statistically significant difference among the groups in terms of duration of effect (p=0.012). Further investigation into the source of the statistically significant difference in duration of effect among the groups revealed a significant difference between Group 2 and Group 1 (p=0.014), as well as between Group 2 and Group 3 (p=0.043). No statistically significant difference was found between Group 1 and Group 3 (p=0.837). With this study, it was observed that when the prepared AboBoNT A solution was frozen and stored at -18°C for up to two weeks, there was no statistically significant difference in terms of efficacy and duration of effect compared to freshly prepared solution. However, the toxin that was kept in the refrigerator at +4°C for two weeks showed a shorter maximum effectiveness duration and a quicker termination of effect compared to the freshly prepared solution. Nevertheless, it should be noted that for AboBoNT A to have optimal efficacy, it is recommended by the manufacturer to be stored at 2-8°C and the cold chain should be maintained throughout the storage period.