{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,15]],"date-time":"2026-10-15T10:08:51Z","timestamp":1792058931131,"version":"4.4.0"},"reference-count":20,"publisher":"Wiley","issue":"7","license":[{"start":{"date-parts":[[2026,7,11]],"date-time":"2026-07-11T00:00:00Z","timestamp":1783728000000},"content-version":"vor","delay-in-days":10,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"},{"start":{"date-parts":[[2026,7,1]],"date-time":"2026-07-01T00:00:00Z","timestamp":1782864000000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["ascpt.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Clinical Translational Sci"],"published-print":{"date-parts":[[2026,7]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>COVID\u201019 continues to be a threat to global health and a burden on healthcare systems. There is an ongoing need for COVID\u201019 antiviral therapies that are safe and effective across broad patient populations. Ibuzatrelvir is a potent, selective inhibitor of the SARS\u2010CoV\u20102 main protease and demonstrated favorable properties for clinical development. We report safety, tolerability, and pharmacokinetic data for ibuzatrelvir from a phase 1 first\u2010in\u2010human study in healthy adults. Study parts evaluated ibuzatrelvir as single or multiple ascending doses, including analysis of participants in fasted and fed states, pharmacokinetics in Chinese and Japanese participants, relative bioavailability of crystalline tablet formulations, and dose selection for patients with COVID\u201019. Oral administration of ibuzatrelvir led to rapid absorption after all doses, and steady\u2010state plasma concentrations were achieved by Day 2 for all doses. High\u2010fat meals decreased maximum plasma concentration and area under the plasma concentration\u2010time curve from time 0 to the time of the last quantifiable concentration, but the concentration at 12\u2009h postdose was comparable when administered without food. Exposures of ibuzatrelvir were similar between Chinese and non\u2010Chinese participants, as well as between Japanese and non\u2010Japanese participants. Ibuzatrelvir was safe and well\u2010tolerated, with no serious or severe adverse events reported and no participants discontinuing. In conclusion, pharmacokinetics and safety were established for single\u2010agent oral ibuzatrelvir, supporting the design and dose selection for further phase 2 trials and the continued development of ibuzatrelvir (NCT05580003).<\/jats:p>","DOI":"10.1111\/cts.70659","type":"journal-article","created":{"date-parts":[[2026,7,11]],"date-time":"2026-07-11T08:51:54Z","timestamp":1783759914000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["A Multipart Phase 1 Study to Assess Safety and Pharmacokinetics of Ibuzatrelvir in Healthy Participants and Dose Selection for a Dose\u2010Ranging Study"],"prefix":"10.1111","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6298-8219","authenticated-orcid":false,"given":"Ravi Shankar P.","family":"Singh","sequence":"first","affiliation":[{"name":"Pfizer Research and Development  Cambridge Massachusetts USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sima S.","family":"Toussi","sequence":"additional","affiliation":[{"name":"Pfizer Research and Development  New York New York USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-3178-6329","authenticated-orcid":false,"given":"Frances","family":"Hackman","sequence":"additional","affiliation":[{"name":"Pfizer Research and Development  Tadworth UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6597-3717","authenticated-orcid":false,"given":"Mona","family":"Shahbazi","sequence":"additional","affiliation":[{"name":"Pfizer Research and Development  New York New York USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5802-0539","authenticated-orcid":false,"given":"John","family":"Prybylski","sequence":"additional","affiliation":[{"name":"Pfizer Research and Development  Groton Connecticut USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8530-3427","authenticated-orcid":false,"given":"Siddhee A.","family":"Sahasrabudhe","sequence":"additional","affiliation":[{"name":"Pfizer Research and Development  Cambridge Massachusetts USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Penelope","family":"Crownover","sequence":"additional","affiliation":[{"name":"Pfizer Research and Development  Groton Connecticut USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3724-6517","authenticated-orcid":false,"given":"Eugene P.","family":"Kadar","sequence":"additional","affiliation":[{"name":"Pfizer Research and Development  Groton Connecticut USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-4587-6279","authenticated-orcid":false,"given":"Billy T.","family":"George","sequence":"additional","affiliation":[{"name":"Pfizer Research and Development  Groton Connecticut USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4455-5780","authenticated-orcid":false,"given":"Negar Niki","family":"Alami","sequence":"additional","affiliation":[{"name":"Pfizer Research and Development  Groton Connecticut USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Arthur","family":"Bergman","sequence":"additional","affiliation":[{"name":"Pfizer Research and Development  Groton Connecticut USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,7,11]]},"reference":[{"key":"e_1_2_11_2_1","article-title":"Covid\u201019: WHO Declares End of Global Health Emergency","volume":"381","author":"Wise J.","year":"2023","journal-title":"BMJ (Clinical Research ed.)"},{"key":"e_1_2_11_3_1","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pone.0275699"},{"key":"e_1_2_11_4_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.nmni.2024.101225"},{"key":"e_1_2_11_5_1","unstructured":"Centers for Disease Control and Prevention Provisional COVID\u201019 Death Counts by Week Ending Date and Stateaccessed at August 26 2025 https:\/\/data.cdc.gov\/NCHS\/Provisional\u2010COVID\u201019\u2010Death\u2010Counts\u2010by\u2010Week\u2010Ending\u2010D\/r8kw\u20107aab."},{"key":"e_1_2_11_6_1","unstructured":"World Health Organization Coronavirus Disease (COVID\u201019) Epidemiological Updates and Monthly Operational Updatesaccessed at August 26 2025 https:\/\/www.who.int\/emergencies\/diseases\/novel\u2010coronavirus\u20102019\/situation\u2010reports."},{"key":"e_1_2_11_7_1","unstructured":"Pfizer Inc Fact Sheet for Healthcare Providers: Emergency Use Authorization for Paxlovidaccessed at: August 26 2025 https:\/\/labeling.pfizer.com\/ShowLabeling.aspx?id=16474."},{"key":"e_1_2_11_8_1","unstructured":"Paxlovid (nirmatrelvir tablets; ritonavir tablets). Full Prescribing Information 2024Pfizer Inc New York NY USA."},{"key":"e_1_2_11_9_1","unstructured":"Veklury (remdesivir). Full Prescribing Information 2025Gilead Sciences Inc. Foster City CA USA."},{"key":"e_1_2_11_10_1","unstructured":"Merck Sharp & Dohme LLC Fact Sheet for Healthcare Providers: Emergency Use Authorization for Lagevrio (molnupiravir) CapsulesAvailable at: August 26 2025 https:\/\/www.merck.com\/eua\/molnupiravir\u2010hcp\u2010fact\u2010sheet.pdf."},{"key":"e_1_2_11_11_1","unstructured":"COVID\u201019 Treatment Guidelines Panel & National Institutes of Health Coronavirus Disease 2019 (COVID\u201019) Treatment Guidelinesaccessed at: August 26 2025 https:\/\/www.ncbi.nlm.nih.gov\/books\/NBK570371\/pdf\/Bookshelf_NBK570371.pdf."},{"key":"e_1_2_11_12_1","doi-asserted-by":"publisher","DOI":"10.15585\/mmwr.mm7303a2"},{"key":"e_1_2_11_13_1","doi-asserted-by":"publisher","DOI":"10.1208\/s12248-023-00832-3"},{"key":"e_1_2_11_14_1","doi-asserted-by":"publisher","DOI":"10.1016\/S1473\u20103099(23)00118\u20104"},{"key":"e_1_2_11_15_1","doi-asserted-by":"publisher","DOI":"10.1021\/acs.jmedchem.3c02469"},{"key":"e_1_2_11_16_1","doi-asserted-by":"publisher","DOI":"10.1126\/science.abl4784"},{"key":"e_1_2_11_17_1","unstructured":"S. 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