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附件5.1

美洲大道1095号 纽约，纽约州，邮编：10036-6797 +1-212-698-3500 +1-212-698-3599传真 www.dechert.com

2024年4月3日

女士们、先生们：

我们曾担任美国特拉华州公司(以下简称“本公司”)Aqutive Treeutics，Inc.的法律顾问，涉及本公司准备和提交一份采用S-3表格的注册声明(“注册声明”)，该注册声明于今天根据修订后的1933年证券法(“证券法”)提交给美国证券交易委员会(“委员会”)，涉及本公司建议的公开发行股票，总金额最高可达$250,000,000,000本公司的以下证券：(1)普通股，公司每股票面价值0.001美元(“普通股”)；(2)公司的优先股，每股面值0.001美元的股份(“优先股”)；(3)公司购买普通股、优先股、债务证券或单位的认股权证(“认股权证”)(“认股权证”)；(4)将根据 公司与其中指定的受托人(“受托人”)之间的契约发行的债务证券(“受托人”)(该契约可不时修订或补充，称为“契约”)；(5)公司购买普通股、优先股、债务证券或单位的权利(“权利”)；及(6)由普通股、优先股、认股权证、债务证券或权利(“单位”)的任何组合组成的公司单位。普通股、优先股、认股权证、债务证券、权利和单位在本文中统称为证券。

注册说明书规定，该等证券可按招股说明书(载于注册说明书及构成注册说明书的一部分)所载招股说明书所载的金额、价格及条款，或于注册说明书所载的招股说明书的一份或多份副刊(每份为“招股说明书副刊”)内分别发售或一并发售。

本意见书是根据证券法S-K条例第601(B)(5)项的要求向本公司提交的，本意见书并未就任何与注册声明内容有关的事项发表意见，但对下文所述证券的有效性除外。

Aqutive Treeutics，Inc.
2024年4月3日
第2页

至于本意见所依据的事实，吾等在其认为适当的范围内依赖公职人员的证书及本公司的代理人、高级人员、董事、雇员及代表及会计师的书面声明，并在这方面假设该等证书及声明的真实性。我们没有独立地确立如此依赖的事实。

在我们的审查中，我们假设所有签名的真实性、所有提交给我们的文件作为原始文件的真实性、作为副本提交给我们的所有文件与原始文件的一致性 、作为我们检查的文件的签字人的自然人的法律行为能力以及代表所有文件各方(公司除外)签名的所有人的法律权力和权威。我们 进一步假设，我们用来构成以下意见基础的任何协议、文件或文书没有任何口头修改、修改或补充(包括任何明示或默示的放弃) 。

根据上述情况，并在符合本函所述假设、限制和限制的前提下，我们认为，截至本函日期，我们认为：

Aqutive Treeutics，Inc.
2024年4月3日
第3页

The opinions set forth herein are subject to the following assumptions, qualifications, limitations and exceptions being true and correct at or before the time of the delivery of any Securities offered pursuant to the Registration Statement and appropriate Prospectus Supplement: (i) the Board of Directors, including any appropriate committee appointed thereby, shall have (x) duly established the terms of the Securities (and in the case of the Units, the Securities that are the components thereof), and (y) duly authorized and taken any other necessary corporate or other action to approve the creation, if applicable, issuance and sale of the Securities and related matters (including with respect to Preferred Stock, the execution, acknowledgment and filing of a Certificate of Designation stating the designation and voting rights, preferences, limitations and special rights, if any, of any such Preferred Stock in accordance with the applicable provisions of the General Corporation Law of the State of Delaware) and any Securities consisting of Common Stock or Preferred Stock, and any Common Stock or Preferred Stock for or into which any other Securities are exercisable, exchangeable or convertible, shall have been duly reserved for issuance and such authorizations and actions have not been rescinded; (ii) the resolutions establishing the definitive terms of and authorizing the Company to register, offer, sell and issue the Securities shall remain in effect and unchanged at all times during which the Securities are offered, sold or issued by the Company; (iii) the definitive terms of each class and series of the Securities not presently provided for in the Registration Statement or the certificate of incorporation of the Company, and the terms of the issuance and sale of the Securities (x) shall have been duly established in accordance with all applicable law and the Charter, the Indenture (including any amendments or supplements thereto), underwriting agreement, warrant agreement, subscription agreement, unit agreement and any other relevant agreement relating to the terms and the offer and sale of the Securities (collectively, the “Documents”) and the authorizing resolutions of the Board of Directors, and reflected in appropriate documentation reviewed by us, and (y) shall not violate any applicable law, the Charter or the Documents (subject to the further assumption that such Charter and Documents have not been amended from the date hereof in a manner that would affect the validity of any of the opinions rendered herein), or result in a default under or breach of any agreement or instrument binding upon the Company and so as to comply with any restriction imposed by any court or governmental body having jurisdiction over the Company; (iv) upon issuance of any shares of Preferred Stock or Common Stock, or, in the case of Units, of which shares of Preferred Stock or Common Stock are components, including upon exercise, conversion or exchange of Securities, the total number of shares of Preferred Stock or Common Stock issued and outstanding shall not exceed the total number of shares of Preferred Stock or Common Stock that the Company is then authorized to issue under its certificate of incorporation; (v) the interest rate on the Debt Securities shall not be higher than the maximum lawful rate permitted from time to time under applicable law; (vi) the Securities (including any Securities issuable upon exercise, conversion or exchange of other Securities and, in the case of any Units, the Securities that are components thereof), and any certificates or instruments representing the relevant Securities (including any Securities issuable upon exercise, conversion or exchange of other Securities and, in the case of any Units, the Securities that are components thereof), have been duly authenticated, executed, countersigned, registered and delivered upon payment of the agreed-upon legal consideration therefor and have been duly issued and sold in accordance with any relevant agreement, approved by us and, if applicable, duly executed and delivered by the Company and any other appropriate party; (vii) the Indenture (including any amendments or supplements thereto), warrant agreement, subscription agreement, unit agreement and any other relevant agreement has been duly authorized, executed and delivered by, and will constitute a valid and binding obligation of, each party thereto (other than the Company); (viii) the Registration Statement, as amended (including all necessary post-effective amendments), and any additional registration statement filed under Rule 462, shall be effective under the Securities Act, and such effectiveness shall not have been terminated or rescinded; (ix) an appropriate Prospectus Supplement shall have been prepared, delivered and filed in compliance with the Securities Act and the applicable rules and regulations thereunder describing the Securities offered thereby; (x) the Securities shall be issued and sold in compliance with all federal and state securities laws and solely in the manner stated in the Registration Statement and the applicable Prospectus Supplement and there shall not have occurred any change in law affecting the validity of the opinions rendered herein; (xi) if the Securities will be sold pursuant to a firm commitment underwritten offering, the underwriting agreement with respect to the Securities in the form filed as an exhibit to the Registration Statement or any post-effective amendment thereto, or incorporated by reference therein, has been duly authorized, executed and delivered by the Company and the other parties thereto; (xii) the Indenture (including any amendments or supplements thereto) shall have been duly qualified under the Trust Indenture Act of 1939, as amended; (xiii) each agreement or contract referred to herein but not filed as an exhibit to the Registration Statement as of the date hereof shall be governed by the laws of the State of New York; and (xiv) in the case of an agreement or instrument pursuant to which any Securities are to be issued, there shall be no terms or provisions contained therein which would affect the validity of any of the opinions rendered herein.

Aquestive Therapeutics, Inc.
April 3, 2024
Page 4

Any opinion set forth herein as to enforceability of obligations of the Company is subject to: (i) bankruptcy, insolvency, reorganization, fraudulent conveyance, moratorium or similar laws now or hereinafter in effect affecting the enforcement of creditors’ rights generally, and by general principles of equity (regardless of whether enforcement is sought in a proceeding in equity or at law) and the discretion of the court or other body before which any proceeding may be brought; (ii) provisions of law that may require that a judgment for money damages rendered by a court in the United States be expressed only in United States dollars; (iii) requirements that a claim with respect to any Debt Securities denominated other than in U.S. dollars (or a judgment denominated other than in U.S. dollars in respect of such claim) be converted into U.S. dollars at a rate of exchange prevailing on a date determined pursuant to applicable law; and (iv) governmental authority to limit, delay or prohibit the making of payments outside the United States or in foreign currency or composite currency.

We express no opinion as to the validity, legally binding effect or enforceability of any provision in any agreement or instrument that (i) requires or relates to payment of any interest at a rate or in an amount that a court would determine in the circumstances under applicable law to be higher than the maximum lawful rate permitted from time to time or (ii) relates to governing law and submission by the parties to the jurisdiction of one or more particular courts.

The opinion expressed herein is limited to the General Corporation Law of the State of Delaware. We are members of the bar of the State of New York. We express no opinion concerning the laws of any other jurisdiction, and we express no opinion concerning any state securities or “blue sky” laws, rules or regulations, or any federal, state, local or foreign laws, rules or regulations relating to the offer and/or sale of the Securities. The opinions expressed herein are based upon the law as in effect and the documentation and facts known to us on the date hereof.

This opinion letter has been prepared for your use solely in connection with the Registration Statement. We assume no obligation to advise you of any changes in the foregoing subsequent to the effectiveness of the Registration Statement.

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement and to the use of our name in the base prospectus contained therein, under the caption “Legal Matters.” In giving such consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act and the rules and regulations of the Commission thereunder.

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