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Levofloxacin is a broad‐spectrum antibiotic of the fluoroquinolone class used in the paediatric population to treat resistant bacterial infections. Because no commercial option exists, a stable liquid formulation of this antibiotic made with accessible vehicles would be useful. The aim of this study was to develop and assess the stability of levofloxacin suspensions made from commercially available tablets and three different accessible vehicles. Levofloxacin suspensions (50 mg/mL) were compounded using two different commercially available tablets (from Apotex; Toronto, ON, Canada and Sandoz; Boucherville, QC, Canada) and three different vehicles (Ora‐Blend, Oral‐Mix; Medisca, Saint‐Laurent, QC, Canada and Simple Syrup (SS); Laboratoire Atlas Inc., Anjou, QC, Canada). Suitable suspensions in Ora‐Blend and Oral‐Mix were stored at room temperature (25°C) as well as under refrigeration (5°C) in amber plastic bottles for 90 days. Suspensions made with SSwere only stored at 25°C because of sugar crystallisation at 5°C. Suspension concentrations were assessed by HPLC. Suspensions using Apotex levofloxacin tablets produced unsuitable high‐foaming, phase‐separated, non‐homogeneous suspension products in all vehicles tested that were therefore not tested for stability. Levofloxacin suspensions prepared using Sandoz tablets remained chemically and physically stable for 3 months, with >96% recovery according to United States Pharmacopeia criteria (90%–110%) in all three vehicles. The results show that the choice of generic levofloxacin tablets is important when preparing homogeneous suspensions. All three vehicles could be used to prepare levofloxacin suspensions using Sandoz tablets that were physically and chemically stable for 3 months.

Drugs and proteins with poor intestinal permeability have a limited oral bioavailability. To remediate this problem, a receptor-mediated endocytosis and transcytosis approach was explored. Indeed, the nontoxic β subunit of cholera toxin (CTB) can cross the intestinal barrier by binding to receptor GM1. In this study, we explored the use of GM1-binding peptides and CTB as potential covalent carriers of poorly permeable molecules. GM1-binding peptides (G23, P3) and CTB were conjugated to poorly permeable fluorescent probes such as fluorescein isothiocyanate (FITC) and albumin-FITC using triethylene glycol spacers and click chemistry. The affinity of the peptide conjugates with receptor GM1 was confirmed by isothermal titration calorimetry or microscale thermophoresis, and the results suggested the involvement of nonspecific interactions. Conjugating the model drugs to G23 and P3 improved the internalization into Caco-2 and T84 cells, although the process was not dependent on the amount of GM1 receptor. However, conjugation of bovine serum albumin FITC to CTB increased the internalization in the same cells in a GM1-dependent pathway. Peptide conjugates demonstrated a limited permeability through a Caco-2 monolayer, whereas G23 and CTB conjugates slightly enhanced permeability through a T84 cell monolayer compared to model drugs alone. Since CTB can improve the permeability of large macromolecules such as albumin, it is an interesting carrier for the improvement of oral bioavailability of various other macromolecules such as heparins, proteins, and siRNAs.