Betaine- and L-Carnitine-Based Ionic Liquids as Solubilising and Stabilising Agents for the Formulation of Antimicrobial Eye Drops Containing Diacerein.

The therapeutic efficacy of topically administered drugs, however powerful, is largely affected by their bioavailability and, thus, ultimately, on their aqueous solubility and stability. The aim of this study was to evaluate the use of ionic liquids (ILs) as functional excipients to solubilise, stabilise, and prolong the ocular residence time of diacerein (DIA) in eye drop formulations. DIA is a poorly soluble and unstable anthraquinone prodrug, rapidly hydrolysed to rhein (Rhe), for the treatment of osteoarthritis. DIA has recently been evaluated as an antimicrobial agent for bacterial keratitis. Two ILs based on natural zwitterionic compounds were investigated: L-carnitine C6 alkyl ester bromide (Carn6), and betaine C6 alkyl ester bromide (Bet6). The stabilising, solubilising, and mucoadhesive properties of ILs were investigated, as well as their cytotoxicity to the murine fibroblast BALB/3T3 clone A31 cell line. Two IL-DIA-based eye drop formulations were prepared, and their efficacy against both Staphylococcus aureus and Pseudomonas aeruginosa was determined. Finally, the eye drops were administered in vivo on New Zealand albino rabbits, testing their tolerability as well as their elimination and degradation kinetics. Both Bet6 and Carn6 have good potential as functional excipients, showing solubilising, stabilising, mucoadhesive, and antimicrobial properties; their in vitro cytotoxicity and in vivo ocular tolerability pave the way for their future use in ophthalmic applications.

Lung-Directed Bacteriotherapy in Cystic Fibrosis: Could It Be an Option?

Due to the alarming spread of bacterial resistance to conventional drugs, the sole use of antibiotics to fight lung infections in cystic fibrosis (CF) is not resolutive, and novel strategies to replace or complement the use of antibiotics are highly desirable. Among these strategies, the use of probiotics is emerging as a particularly attractive approach. Probiotic administration via the oral route has demonstrated an ability to improve lung function and to reduce infection and exacerbation rates in CF patients through mechanisms mainly attributable to the gut-lung axis. Nevertheless, some studies reported no beneficial effect of probiotic intake suggesting that there is margin for improvement of such innovative intervention in CF. The present review aims to address the rationale behind probiotic use in CF and discuss the hypothesis that nasal/aerosol administration of appropriate probiotic strains may help to exert a direct beneficial effect on the respiratory tract, increasing the effectiveness of probiotic interventions in CF patients.