Formulation of the Microbicide INP0341 for In Vivo Protection against a Vaginal Challenge by Chlamydia trachomatis

Abstract

The salicylidene acylhydrazide (SA) compounds have exhibited promising microbicidal properties. Previous reports have shown the SA compounds, using cell cultures, to exhibit activity against Chlamydia trachomatis, herpes simplex virus and HIV-1. In addition, using an animal model of a vaginal infection the SA compound INP0341, when dissolved in a liquid, was able to significantly protect mice from a vaginal infection with C. trachomatis. To expand upon this finding, in this report INP0341 was formulated as a vaginal gel, suitable for use in humans. Gelling agents (polymers) with inherent antimicrobial properties were chosen to maximize the total antimicrobial effect of the gel. In vitro formulation work generated a gel with suitable rheology and sustained drug release. A formulation containing 1 mM INP0341, 1.6 wt% Cremophor ELP (solubility enhancer) and 1.5 wt% poly(acrylic acid) (gelling and antimicrobial agent), was chosen for studies of efficacy and toxicity using a mouse model of a vaginal infection. The gel formulation was able to attenuate a vaginal challenge with C. trachomatis, serovar D. Formulations with and without INP0341 afforded protection, but the inclusion of INP0341 increased the protection. Mouse vaginal tissue treated with the formulation showed no indication of gel toxicity. The lack of toxicity was confirmed by in vitro assays using EpiVaginal tissues, which showed that a 24 h exposure to the gel formulation did not decrease the cell viability or the barrier function of the tissue. Therefore, the gel formulation described here appears to be a promising vaginal microbicide to prevent a C. trachomatis infection with the potential to be expanded to other sexually transmitted diseases.

Targeting bacterial pathogenesis by inhibiting virulence-associated Type III and Type IV secretion systems

“…They were among the earliest identified secretion system inhibitors and remain the best-studied compound family to date (Table 1) (Duncan et al, 2012;Beckham and Roe, 2014;Mühlen and Dersch, 2020). Slepenkin et al, 2003;Muschiol et al, 2006;Wolf et al, 2006;Bailey et al, 2007;Slepenkin et al, 2007;Slepenkin et al, 2011;Ur-Rehman et al, 2012;Pedersen et al, Kauppi et al, 2003;Nordfelth et al, 2005;Wang et al, 2011) B8I-1, -2, -3, -4, -5 VirB8 Brucella (Paschos et al, 2011;Smith et al, 2012) * and # = indicate connections between compounds and targets listed in the respective row SAHs and their derivatives were first described as inhibitors of the Yersinia T3SS by Kauppi et al (2003). The authors used a transcriptional fusion of the yopE gene (encoding the effector protein YopE) and luciferase and identified 30 molecules that significantly reduced luciferase expression.…”

“…Further in vitro studies showed that this inhibitor affected neither essential members of the vaginal microbiome, nor the integrity of the vaginal mucosa, and showed only mild cytotoxicity. It was also observed that it could protect from vaginal Chlamydia infection in a mouse model (Slepenkin et al, 2011;Pedersen et al, 2014). After the initial in vivo experiments, the inhibitor was improved and formulated as a vaginal gel suitable for use in humans (Pedersen et al, 2014).…”

Anti-Virulence Therapeutic Approaches for Neisseria gonorrhoeae

“…AVTs that could be applied preemptively in the community to suppress asymptomatic transmission are likely to have the highest benefit, particularly for women who are at the highest risk of developing PID which increases the risk of infertility. Modes of delivery that would most likely benefit women would either involve oral delivery or direct topical applications via hygiene products such as commercial vaginal microbicides, some of which have viricidal and anti-chlamydial properties [ 298 , 299 , 300 , 301 ].…”

Polymeric gels for intravaginal drug delivery

“…Polycarbophil and carbopol were used to deliver a poorly water-soluble salicylidene acylhydrazide compound by Pedersen et al [74]. A solubility enhancer, cremaphor, was used to allow the compound to be dissolved in the aqueous gel.…”