Eudragit® FS Microparticles Containing Bacteriophages, Prepared by Spray-Drying for Oral Administration

Abstract

Phage therapy is recognized to be a promising alternative to fight antibiotic-resistant infections. In the quest for oral dosage forms containing bacteriophages, the utilization of colonic-release Eudragit^® derivatives has shown potential in shielding bacteriophages from the challenges encountered within the gastrointestinal tract, such as fluctuating pH levels and the presence of digestive enzymes. Consequently, this study aimed to develop targeted oral delivery systems for bacteriophages, specifically focusing on colon delivery and employing Eudragit^® FS30D as the excipient. The bacteriophage model used was LUZ19. An optimized formulation was established to not only preserve the activity of LUZ19 during the manufacturing process but also ensure its protection from highly acidic conditions. Flowability assessments were conducted for both capsule filling and tableting processes. Furthermore, the viability of the bacteriophages remained unaffected by the tableting process. Additionally, the release of LUZ19 from the developed system was evaluated using the Simulator of the Human Intestinal Microbial Ecosystem (SHIME^®) model. Finally, stability studies demonstrated that the powder remained stable for at least 6 months when stored at +5 °C.

Keywords: Eudragit® FS; bacteriophage; capsules; colon-targeting; phage-therapy; spray-drying; tablets.

Figure 1

pH (A) and temperature (B) stability results of LUZ19 bacteriophages in liquid form for one hour (n = 3). “ns”: p > 0.05, *: p < 0.05 “****”: p ≤ 0.0001. For graphic A, the activity at pH 2 and pH 12 is null.

Figure 2

Effect of the different excipient ratios on bacteriophage survival following spray-drying and after exposure to pH = 2 for a period of 2 h (blue curve: titers after neutral resuspension with DPBS pH 7.4 showed the effect of both formulation and process; red curve: titers after acid resuspension showed the effect of the whole process of encapsulation, and the resultant acid protection).

Figure 3

Scanning electronic micrographs of the surface of a particle containing LUZ19 encapsulated in 100:0% w/w of D-(+)-trehalose/L-isoleucine: Eudragit^® FS/PlasACRYL^® T20.

Figure 4

Scanning electronic micrographs of the surface of a particle containing LUZ19 encapsulated in 20:80 % w/w of D-(+)-trehalose/L-isoleucine: Eudragit^® FS30D/PlasACRYL^® T20 (F4).

Figure 5

Liberation profile of LUZ19 encapsulated (F4) at pH > 7 for 5 h (blue curve). The red dashed lines represent the low and high limits of activity of the control (powder whose activity was tested with resuspension in DPBS).

Figure 6

Activity (PFU/mg) of the bacteriophages in F4 powder according to storage temperature, relative humidity (HR), and time “ns”: p > 0.05 and “****”: p ≤ 0.0001.