The development of oral solid dosage forms using the direct-compression tableting of spray-dried bacteriophages suitable for targeted delivery and controlled release

This study addresses the challenge of developing a cheap, patient-friendly alternative to antibiotics using bacteriophages for gastrointestinal applications. It explores the feasibility of manufacturing an enteric solid dosage form containing a salmonella-specific Myoviridae phage, Felix O1, encapsulated in spray-dried trehalose/Eudragit microparticles. The spray-dried powder was further formulated by combining the spray-dried microparticles with magnesium stearate to facilitate the fabrication of tablets using direct compression. The paper presents a comprehensive evaluation of the tablets with measurements of phage viability during tablet fabrication using a range of compression settings and, after tablet disintegration, dissolution and friability. Phage viability measurements were performed using storage stability testing of spray-dried powders and tablets in sealed vials at 4 °C, 20 °C and 30 °C and under different humidity conditions of 0%, 50% and 65% RH. The recommended compression force range was found to be 10–15 kN for a standard 10 mm diameter tablet. The storage of tablets at 4 °C/0% RH was found to be the most favourable condition resulting in a ~1 log loss in titre over a six-month storage period. Storage at higher temperatures and samples exposed to high levels of humidity resulted in a significant loss in phage viability. The paper highlights challenges in developing phage formulations suitable for direct-compression tableting, which afford the phages protection when exposed to temperatures and humidity levels that do not require a cold supply chain.