NRX Pharmaceuticals Inc美股招股说明书(2026-06-02版)

SUBJECT TO COMPLETION, DATED JUNE 2, 2026 Filed pursuant to Rule424(b)(5)Registration No.333-288205 Preliminary Prospectus Supplement(to Prospectus dated December 22, 2025) Shares of Common Stock NRx Pharmaceuticals, Inc. (“NRx,” the “Company,” “we” or “our”) is offeringshares of its common stock, par value $0.001per share (the “Common Stock”) pursuant to this prospectus supplement (this “Prospectus Supplement”) and the accompanying baseprospectus (the “Base Prospectus”). The public offering price for each share of Common Stock is $. We have granted the underwriters the option to purchase, exercisable within a 30-day period, up to an additional shares ofCommon Stock. We are offering all of the shares of Common Stock offered by this Prospectus Supplement on a firm commitmentunderwritten basis. Our Common Stock is listed on The Nasdaq Capital Market (“Nasdaq”) under the symbol “NRXP.” On June 1, 2026, the lastreported sale price of our Common Stock on Nasdaq was $4.62per share. Investing in our securities involves a high degree of risk, including the risk of a substantial loss of investment. Beforepurchasing any shares of our common stock, you should read the discussion of the principal risks of investing in our securities,which are summarized in“Risk Factors”beginning on pageS-5of the Prospectus Supplement and page3of the Base Prospectus,as well as in other documents incorporated by reference into this Prospectus Supplement. (1)See “Underwriting” beginning on page S-10for additional information regarding compensation payable in connection with this offering.(2)If the underwriters exercisetheiroption to purchase additional shares of Common Stock in full, the total underwriting discounts and commissionspayable by us will be $, and the total proceeds to us, before expenses, will be $. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved ofthese securities or passed upon the adequacy or accuracy of this Prospectus Supplement or the accompanying Base Prospectus.Any representation to the contrary is a criminal offense. Delivery of the shares of Common Stock offered hereby is expected to be made on or about June, 2026, subject to thesatisfaction of certain closing conditions. Lead Bookrunning Manager BTIG Joint Bookrunning Manager Lucid Capital Markets The date of this Prospectus Supplement is June, 2026. TABLE OF CONTENTS About this Prospectus SupplementS-1Cautionary Note Regarding Forward-Looking StatementsS-2SummaryS-3Risk FactorsS-5Use of ProceedsS-8DilutionS-9UnderwritingS-10Legal MattersS-16ExpertsS-16Where You Can Find More InformationS-16Incorporation of Documents by ReferenceS-16 PROSPECTUS About This Prospectus1Prospectus Summary2Risk Factors3Cautionary Note Regarding Forward-Looking Statements4Use of Proceeds5Description of our Capital Stock6Description of the Debt Securities9Description of the Depositary Shares18Description of the Warrants21Description of the Rights22Description of the Purchase Contracts23Description of the Units23Description of Certain Provisions of Delaware Law and our Certificate of Incorporation and Bylaws24Plan of Distribution25Legal Matters27Experts27Where You Can Find More Information28Incorporation of Certain Information by Reference28 ABOUT THIS PROSPECTUS SUPPLEMENT This Prospectus Supplement and the accompanying Base Prospectus are part of a “shelf” registration statement on Form S-3, asamended, (File No. 333-288205) that we originally filed with the U.S. Securities and Exchange Commission (the “SEC”), on June 20,2025, and an amendment thereto on December 12, 2025 and which became effective on December 22, 2025. Under this shelf registrationprocess, we may, from time to time, sell shares of our Common Stock in one or more offerings. This Prospectus Supplement and the accompanying Base Prospectus do not contain all of the information in the registrationstatement. We have omitted certain parts of the registration statement, as permitted by the rules and regulations of the SEC. You shouldread this entire Prospectus Supplement and the accompanying Base Prospectus, together with the additional information described thereinunder the headings “Incorporation of Certain Documents by Reference” and “Where You Can Find More Information” carefully beforemaking an investment decision. The accompanying Base Prospectus, including the documents incorporated by reference therein, providesmore general information, some of which may not apply to this offering. Generally, when we refer to this “Prospectus,” we are referringto both this Prospectus Supplement and the accompanying Base Prospectus combined. You should rely only on the information contained, or incorporated by reference, in this Prospectus Supplement and theaccompanying Base Prospectus. Neither we nor the underwriters have authorized anyone to provide you with different information. Ifanyone provides you with different or inconsistent information, you sh