(B-67) Development of Anti-Viral Loaded Injectable, Biodegradable In Situ Gelling Systems for Sustained Release and Anti-Viral Treatment

Introduction:: As of April 2023, over 762 million people have been diagnosed with COVID-19 cases and over 6.8 million of those cases resulted in mortality [1]. Vaccination has significantly impacted the COVID-19 epidemic in reducing cases and deaths [2]. However, 2.3 billion people still remain unvaccinated and 89% of these people are located in developing countries [2,3]. Remdesivir, a nucleoside antiviral agent, has shown clinical effect in reducing ventilation time and hospitalization, and is the only anti-viral agent fully FDA approved for treating COVID-19 patients. GS-441524, a metabolite of Remdesivir, has similar antiviral effect as Remdesivir with a much lower manufacturing cost. However, both drugs require daily intravenous administration for therapeutic effect, which can be difficult for patients in developing countries to receive. Remdesivir and GS-441524 have half-lives of about 1h and 25 h respectively, and thus it is important to develop a drug delivery system to sustain release them to continually treat COVID-19 infections [4]. Additionally, Dexamethasone, a widely used corticoid, has shown clinical ability to help treat the inflammation response associated with the COVID-19 cytokine storm and reduce mortality [5]. Our lab has been developing injectable, biodegradable in situ depot forming gelling systems (ISD) with FDA approved components for sustained release of small molecules. The objective of this work is to develop Remdesivir, GS-441524, and Dexamethasone loaded ISDs for sustained release and treating COVID-19.

Materials and Methods:: ISDs polymer solutions were prepared by dissolving PLGA and PLA co-polymer blends in a mixture of solvents of N-Methyl Pyrrolidinone and Triethyl Citrate. Remdesivir, GS-441524, or Dexamethasone is combined with the ISD polymer solution, and the anti-viral-loaded ISDs were injected into 4 mL PBS (pH 7.4) to form the ISD. The ISDs were kept in PBS (pH 7.4) at 37 °C under stirring and the release medium was collected at selected time points and replaced by fresh PBS (pH 7.4) for several months. The amount of Remdesivir, GS-441524, or Dexamethasone released was quantified by LC-MS/MS (Xevo TQS Chronos). ISDs are also taken out from release medium at select time points, flash frozen with LN2, and lyophilized for morphology evaluation using Scanning Electron Microscopy (SEM). Dexamethasone loaded ISDs are additionally evaluated via SEM-Electron Dispersive X-ray Spectroscopy (EDS) to visualize location of Dexamethasone on ISD surface.

Results, Conclusions, and Discussions:: The results show that ISDs slowly released GS-41524 for 100 days, Remdesivir for 60 days, and Dexamethasone for 30 days. Release of GS-441524, Remdesivir, and Dexamethasone can be manipulated by changing the ISD volume, total polymer content, PLA content, and loading content of drug. Changes in surface morphology are visualized by SEM, with differences in size and abundance of pores correlating to ISD volume, time point, and loading content of drug. ISDs show isolated pores in the beginning of the release, and the pores became smaller and the depots became more dense with time. Dexamethasone is visualized via detection of fluorine through SEM-EDS and demonstrates a higher percentage of fluorine at the surface at earlier timepoints. Herein, we are able to demonstrate a biodegradable, injectable in situ gelling system that can sustain release anti-viral and viral treatment agents for COVID-19 treatment. Additionally, key formulation parameters have been identified to tune release kinetics and thus drug dosing. Work is being continued to evaluate later timepoints of release studies to evaluate and extend duration of release as well as work on evaluating in vitro anti-viral effect of ISD released anti-viral agents. Future work will be performed to evaluate in vivo anti-viral effect against COVID-19 to provide key information about biotherapeutic efficacy and pharmacokinetics of ISDs. If successful, these anti-viral ISDs will provide low-cost self-administrable forms for developing countries to treat COVID-19 infections.

Acknowledgements (Optional): : We would like to thank Frederick G. Smith, MS, DDS and Venice K. Paterakis, DDS Endowment Fund and the Medical Device Sprint Challenge UM Ventures Fund for financial support.

References (Optional): : [1] WHO Coronavirus Dashboard 2023; https://covid19.who.int/ [2] Rahmah L, Abarikwu SO, Arero AG, et al. Pharmacol Rep. 2022; 74(6):1326-1327 [3] Pandem-ic “Mapping our unvaccinated word” 2023; https://pandem-ic.com/mapping-our-unvaccinated-world/ [4] Humeniuk, R., Mathias, A., Kirby, B.J. et al. Clinical Pharmacokinetics 2021; 60: 569–583 [5] The RECOVERY Collaborative Group. N Engl J Med 2021; 384:693-704