{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,18]],"date-time":"2026-06-18T13:54:51Z","timestamp":1781790891122,"version":"3.54.5"},"reference-count":34,"publisher":"Public Library of Science (PLoS)","issue":"11","license":[{"start":{"date-parts":[[2022,11,10]],"date-time":"2022-11-10T00:00:00Z","timestamp":1668038400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Gofundme"},{"DOI":"10.13039\/100018693","name":"HORIZON EUROPE Framework Programme","doi-asserted-by":"publisher","award":["871029"],"award-info":[{"award-number":["871029"]}],"id":[{"id":"10.13039\/100018693","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS ONE"],"abstract":"<jats:p>Despite new antivirals are being approved against SARS-CoV-2 they suffer from significant constraints and are not indicated for hospitalized patients, who are left with few antiviral options. Repurposed drugs have previously shown controversial clinical results and it remains difficult to understand why certain trials delivered positive results and other trials failed. Our manuscript contributes to explaining the puzzle: this might have been caused by a suboptimal drug exposure and, consequently, an incomplete virus suppression, also because the drugs have mostly been used as add-on monotherapies. As with other viruses (e.g., HIV and HCV) identifying synergistic combinations among such drugs could overcome monotherapy-related limitations. In a cell culture model for SARS-CoV-2 infection the following stringent criteria were adopted to assess drug combinations: 1) identify robust, synergistic antiviral activity with no increase in cytotoxicity, 2) identify the lowest drug concentration inhibiting the virus by 100% (LIC<jats:sub>100<\/jats:sub>) and 3) understand whether the LIC<jats:sub>100<\/jats:sub> could be reached in the lung at clinically indicated drug doses. Among several combinations tested, remdesivir with either azithromycin or ivermectin synergistically increased the antiviral activity with no increase in cytotoxicity, improving the therapeutic index and lowering the LIC<jats:sub>100<\/jats:sub> of every one of the drugs to levels that are expected to be achievable and maintained in the lung for a therapeutically relevant period of time. These results are consistent with recent clinical observations showing that intensive care unit admission was significantly delayed by the combination of AZI and RDV, but not by RDV alone, and could have immediate implications for the treatment of hospitalized patients with COVID-19 as the proposed \u201cdrug cocktails\u201d should have antiviral activity against present and future SARS-CoV-2 variants without significant overlapping toxicity, while minimizing the onset of drug resistance. Our results also provide a validated methodology to help sort out which combination of drugs are most likely to be efficacious <jats:italic>in vivo<\/jats:italic>, based on their <jats:italic>in vitro<\/jats:italic> activity, potential synergy and PK profiles.<\/jats:p>","DOI":"10.1371\/journal.pone.0276751","type":"journal-article","created":{"date-parts":[[2022,11,10]],"date-time":"2022-11-10T18:33:18Z","timestamp":1668105198000},"page":"e0276751","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":10,"title":["Synergistic drug combinations designed to fully suppress SARS-CoV-2 in the lung of COVID-19 patients"],"prefix":"10.1371","volume":"17","author":[{"given":"Davide","family":"De Forni","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Barbara","family":"Poddesu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Giulia","family":"Cugia","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"James","family":"Chafouleas","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Julianna","family":"Lisziewicz","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Franco","family":"Lori","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2022,11,10]]},"reference":[{"issue":"7885","key":"pone.0276751.ref001","doi-asserted-by":"crossref","first-page":"358","DOI":"10.1038\/d41586-021-03074-5","article-title":"\u00abCOVID antiviral pills: what scientists still want to know,\u00bb","volume":"599","author":"H Ledford","year":"2021","journal-title":"Nature"},{"issue":"7894","key":"pone.0276751.ref002","doi-asserted-by":"crossref","first-page":"496","DOI":"10.1038\/d41586-022-00112-8","article-title":"\u00abWhy scientists are racing to develop more COVID antivirals,\u00bb","volume":"601","author":"M Kozlov","year":"2022","journal-title":"Nature"},{"key":"pone.0276751.ref003","unstructured":"\u00abU.S.F.D., Coronavirus (COVID-19) update: FDA Authorizes First Oral Antiviral for Treatment of COVID-19,\u00bb 2021. [Online]. Available: https:\/\/fda.goc\/news-events\/press-announcements\/coronavirus-covid-19-update-fda-authorizes-first-oral-antivral-treatment-covid-19."},{"key":"pone.0276751.ref004","unstructured":"\u00abU.S.F.D., Coronavirus (COVID-19) Update: FDA Authorizes Additioanl Oral Antiviral for Treatment of COVID-19 in Certain Adults,\u00bb 2021. [Online]. Available: httos:\/\/www.fda.gov\/news-events\/press-announcements\/coronavirus-covid-19-update-fda-authorizes-additional-oral-antiviral-treatment-covid-19-certain."},{"key":"pone.0276751.ref005","doi-asserted-by":"crossref","first-page":"693775","DOI":"10.3389\/fimmu.2021.693775","article-title":"\u00abCrucial Mutations of Spike Protein on SARS-CoV-2 Evolved to Variant Strains Escaping Neutralization of Convalescent Plasmas and RBD-Specific Monoclonal Antibodies,\u00bb","volume":"12","author":"C Ding","year":"2021","journal-title":"Fron Immunol"},{"issue":"6","key":"pone.0276751.ref006","doi-asserted-by":"crossref","first-page":"497","DOI":"10.1056\/NEJMoa2023184","article-title":"\u00abRepurposed Antiviral Drugs for COVID-19\u2014Interim WHO Solidarity Trial Results,\u00bb","volume":"384","author":"WHO Solidarity Trial Consortium","year":"2021","journal-title":"N Engl J Med"},{"issue":"10","key":"pone.0276751.ref007","doi-asserted-by":"crossref","first-page":"1079","DOI":"10.1016\/S2213-2600(21)00289-7","article-title":"\u00abAzithromycin: can its benefit be ruled out in mild COVID-19?,\u00bb","volume":"9","author":"A Rodr\u00edguez-Molinero","year":"2021","journal-title":"Lancet Respir Med"},{"key":"pone.0276751.ref008","article-title":"\u00abIvermectin for Prevention and Treatment of COVID-19 Infection: A Systematic Review, Meta-analysis, and Trial Sequential Analysis to Inform Clinical Guidelines,\u00bb","author":"A Bryant","year":"2021","journal-title":"American Journal of Therapeutics"},{"issue":"5","key":"pone.0276751.ref009","doi-asserted-by":"crossref","first-page":"569","DOI":"10.1007\/s40262-021-00984-5","article-title":"\u00abPharmacokinetic, Pharmacodynamic, and Drug-Interaction Profile of Remdesivir, a SARS-CoV-2 Replication Inhibitor,\u00bb","volume":"60","author":"R Humeniuk","year":"2021","journal-title":"Clin Pharmackinet"},{"issue":"8","key":"pone.0276751.ref010","doi-asserted-by":"crossref","DOI":"10.3390\/pharmaceutics13081181","article-title":"\u00abMathematical Modeling of Remdesivir to Treat COVID-19: Can Dosing Be Optimized?,\u00bb","volume":"13","author":"JM Conway","year":"2021","journal-title":"Pharmaceutics"},{"issue":"12","key":"pone.0276751.ref011","doi-asserted-by":"crossref","first-page":"3574","DOI":"10.1016\/j.xphs.2020.08.024","article-title":"\u00abDevelopment of a Minimal Physiologically-Based Pharmacokinetic Model to Simulate Lung Exposure in Humans Following Oral Administration of Ivermectin for COVID-19 Drug Repurposing,\u00bb","volume":"109","author":"B Jermain","year":"2020","journal-title":"J Pharm Sci"},{"issue":"11","key":"pone.0276751.ref012","doi-asserted-by":"crossref","first-page":"2577","DOI":"10.1128\/AAC.40.11.2577","article-title":"\u00abSafety, toleration, and Pharmacokinetics of intravenous azithromycin,\u00bb","volume":"40","author":"DR 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Integrin-Mediated Endocytosis Even in the Presence of Vaccine-Elicited Neutralizing Antibodies,\u00bb","volume":"14","author":"A Bugatti","year":"2022","journal-title":"Viruses"},{"issue":"7","key":"pone.0276751.ref023","doi-asserted-by":"crossref","first-page":"1978","DOI":"10.1021\/acschembio.2c00411","article-title":"\u00abPeptide-Antibody Fusions Engineered by Phage Display Exhibit an Ultrapotent and Broad Neutralization of SARS-CoV-2 Variants,\u00bb","volume":"17","author":"J Labriola","year":"2022","journal-title":"ACS Chem Biol"},{"issue":"3","key":"pone.0276751.ref024","doi-asserted-by":"crossref","first-page":"540","DOI":"10.1128\/AAC.37.3.540","article-title":"\u00abStrategic design adn three-dimensional analysis of antiviral drug combinations,\u00bb","volume":"37","author":"MN Prichard","year":"1993","journal-title":"Antimicrob Agents 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Wu","year":"2020","journal-title":"Acta Pharm Sin B"},{"key":"pone.0276751.ref028","article-title":"\u00abEnergetics Based Modeling of Hydroxychloroquine and Azithromycin Binding to the SARS-CoV-2 Spike (S)Protein\u2014ACE2 Complex,\u00bb","author":"S Sandeep","year":"2020","journal-title":"ChemRxiv"},{"issue":"2","key":"pone.0276751.ref029","doi-asserted-by":"crossref","first-page":"106020","DOI":"10.1016\/j.ijantimicag.2020.106020","article-title":"\u00abSynergistic antiviral effect of hydroxychloroquine and azithromycin in combination against SARS-CoV-2: What molecular dynamics studies of virus-host interactions reveal,\u00bb","volume":"56","author":"J Fantini","year":"2020","journal-title":"Int JAntimicrob Agents"},{"issue":"20","key":"pone.0276751.ref030","doi-asserted-by":"crossref","first-page":"6785","DOI":"10.1074\/jbc.RA120.013679","article-title":"\u00abRemdesivir is a direct-acting antiviral that inhibits RNA-dependent RNA polymerase from severe acute respiratory syndrome coronavirus 2 with high potency,\u00bb","volume":"295","author":"CJ Gordon","year":"2020","journal-title":"J Biol Chem"},{"key":"pone.0276751.ref031","doi-asserted-by":"crossref","first-page":"101","DOI":"10.4149\/BLL_2021_015","article-title":"\u00abAre clarithromycin, azithromycin and their analogues effective in the treatment of COVID19?,\u00bb","volume":"122","author":"MA Gedikli","year":"2021","journal-title":"Bratisl. Med J"},{"key":"pone.0276751.ref032","doi-asserted-by":"crossref","first-page":"33","DOI":"10.2174\/1874091X02014010033","article-title":"\u00abStudy of the Interaction of Zinc Cation with Azithromycin and its Significance in the COVID-19 Treatment: A Molecular Approach,\u00bb","volume":"14","author":"JH Poupaert","year":"2020","journal-title":"The Open Biochemistry Journal"},{"key":"pone.0276751.ref033","unstructured":"Pfizer, \u00abPfizer\u2019s Novel COVID-19 Oral Antiviral Treatment Candidate Reduced Risk of Hospitalization or Death by 89% in Interim Analysis of Phase 2\/3 EPIC-HR Study,\u00bb 2021. [Online]. Available: https:\/\/www.pfizer.com\/news\/press-release\/press-release-detail\/pfizers-novel-covid-19-oral-antiviral-treatment-candidate."},{"issue":"11","key":"pone.0276751.ref034","doi-asserted-by":"crossref","first-page":"6364","DOI":"10.1111\/1462-2920.15769","article-title":"\u00abClinical trials with antiviral drugs against COVID-19: some progress and many shattered hopes,\u00bb","volume":"23","author":"H Brussow","year":"2021","journal-title":"Environ Microbiol"}],"updated-by":[{"DOI":"10.1371\/journal.pone.0315297","type":"correction","label":"Correction","source":"publisher","updated":{"date-parts":[[2024,12,5]],"date-time":"2024-12-05T00:00:00Z","timestamp":1733356800000}}],"container-title":["PLOS ONE"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0276751","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,11,10]],"date-time":"2022-11-10T18:33:37Z","timestamp":1668105217000},"score":1,"resource":{"primary":{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0276751"}},"subtitle":[],"editor":[{"given":"Hiroj","family":"Bagde","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"editor"}]}],"short-title":[],"issued":{"date-parts":[[2022,11,10]]},"references-count":34,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2022,11,10]]}},"URL":"https:\/\/doi.org\/10.1371\/journal.pone.0276751","relation":{"correction":[{"id-type":"doi","id":"10.1371\/journal.pone.0315297","asserted-by":"object"}]},"ISSN":["1932-6203"],"issn-type":[{"value":"1932-6203","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,11,10]]}}}