This study investigated the potential of developing long-acting injectable (LAI) formulations of the next-generation diarylquinoline antibacterial compounds TBAJ-587 and TBAJ-876, which have the potential to impact the tuberculosis (TB) treatment by providing an extended treatment option. The performance of these compounds, formulated as LAIs, were evaluated based on particle size stability, drug loading capacity, and in vivo pharmacokinetics in rats. The data showed that particularly high drug loadings could be obtained in aqueous suspensions using the salt forms of TBAJ-587 and TBAJ-876, with concentrations up to 750 mg/mL TBAJ-587 fumarate and 650 mg/mL TBAJ-876 tartrate, expressed as the equivalent concentration of free base. A long-term stability study of the TBAJ-876 tartrate formulation suggested that a relatively stable suspension was defined when stored at both ambient temperature and at 40 °C. In contrast, the TBAJ-587 fumarate suspension formulation showed significant particle size growth as a function of time, indicating physical instability in the colloidal system. Analysis of both compounds by X-ray powder diffraction (XRPD) revealed no major changes in the crystal structure following milling or after 24 weeks of storage at 40 °C. The in vivo pharmacokinetic study in rats showed that the suspensions containing either TBAJ-587 fumarate or TBAJ-876 tartrate offered a promising LAI option for the prolonged treatment of TB, as all formulations achieved prolonged drug plasma exposure for at least three months following administration.

A key component of global tuberculosis (TB) control is the treatment of latent TB infection. The use of long-acting technologies to administer TB preventive treatment has the potential to significantly improve the delivery and impact of this important public health intervention. For example, an ideal long-acting treatment could consist of a single dose that could be administered in the clinic (ie, a "1-shot cure" for latent TB). Interest in long-acting formulations for TB preventive therapy has gained considerable traction in recent years. This article presents an overview of the specific considerations and current preclinical advancements relevant for the development of long-acting technologies of TB drugs for treatment of latent infection, including attributes of target product profiles, suitability of drugs for long-acting formulations, ongoing research efforts, and translation to clinical studies.