# Immobilization of Levocyetririzine on Mesoporous Silica for Antiallergenic Gel Formulation
## 4 Conclusions  
Although the immobilization of LevdC on Syloid was successful, only 24.5% coverage was achieved in both aqueous and methanol media. In contrast, with the fixation of the free base of Levo on a Syloid support in a DCM solution with two days of mixing, a surface coverage of 65.5% can be achieved with an active substance content of 23.2% by weight. The binding of the active ingredient to the MSM carrier was clearly demonstrated by XPS and IR tests. The in vitro release experiments in an aqueous solution showed that a significant part of the active substance was released quickly. Then, depending on the conditions used, the release was continuous. The release of Levb from the carrier occurs more slowly than the dissolution of the starting active ingredient. This slower process is influenced by the diffusion of Levb from the pores, which at the same time ensures the extended, longer-lasting effect of the active ingredient. In the in vivo croton oil-induced ear inflammation mouse experiment, the SyLevb-containing gel showed a similar inflammation-reducing effect at half the dose compared to the reference gel. The following supporting information can be downloaded at [[https://www.mdpi.com/article/10.3390/app14209605/s1](https://www.mdpi.com/article/10.3390/app14209605/s1)]([https://www.mdpi.com/article/10.3390/app14209605/s1](https://www.mdpi.com/article/10.3390/app14209605/s1)), Figure S1: Reaction for the production of levocetriarine free base; Figure S2: Levocetriarine base containing Syloid (_sample SyLevb_, A) and gel containing levocetriarine base on Syloid (_gSyLev_, B); Figure S3: IR spectra of samples _SyLev1_, _SyLev2_, _SyLev3_, _SyLev4_, _and SyLev5_, as well as Syloid and levocetriarine; Figure S4: Scanning electron microscopic images of _samples SyLev1_ (A), _SyLev2_ (B), _SyLev3_ (C), _SyLev4_ (D), and _SyLev5_ (E); Figure S5: Typical X-ray photoelectron spectra of levocetriarine adsorbed on silica (sample _SyLev9_). N1s and C1s photoelectron lines are decomposed to various chemical states (C-\(X\) represents carbons connected to heteroatoms (O, N, Cl), except carboxyl); Figure S6: IR spectra of samples _SyLev6_, _SyLev7_, _SyLev8_, _and SyLev9_, as well as Syloid and levocetriarine; Figure S7: DSC trace of samples containing levocetriarine free base on Syloid carrier (_samples SyLev6-SyLev9_); Figure S8: Scanning electron microscopic images of samples _SyLev6_ (A) _SyLev7_ (B), _SyLev8_ (C), and _SyLev9_ (D); Table S1: Surface composition (_atomic_ %) of the pure levocetriarine samples (corrected for carbonaceous contamination). C-X represents the carbon atoms connected to heteroatoms, except the COO group. Conceptualization, K.S. and Z.K. ; methodology, K.S. and Z.M. ; formal analysis, K.S., S.K., K.M., E.B., M.M. ([PERSON]) and L.T. ; investigation, K.S. ; animal expert, A.B.S.-N.; writing--original draft preparation, K.S. ; writing--review and editing, K.S., S.K., Z.M., M.M. ([PERSON]), L.T., T.F. and Z.K. ; visualization, K.S., E.B. and L.T. ; supervision, Z.K. ; project administration, K.S. and Z.K. All authors have read and agreed to the published version of the manuscript. This research work was funded by the European Structural and Investments Funds and the Government of Hungary under the GINOP-2.2.1-15-2016-00023 project. The study adhered to the Declaration of Helsinki guidelines and the EU Directive 2010/63/EU for animal experiments, and was approved by the local animal ethical committee (COEO-mice). All animal procedures were performed under the stipulations of the Protection and Careful Treatment of Animals Decree (40/2013. II. 14., Hungarian Government Decree) and were approved by the Institutional Animal Care and Use Committee (protocol code PE/EA/732-7/2021 and date of approval: 5 August 2021). Not applicable. The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author. [PERSON] is grateful to the Hungarian Academy of Sciences for the [PERSON] Research Fellowship.