EX-5.1

Exhibit 5.1

Akerman LLP

Las Olas Centre II, Suite 1600

350 East Las Olas Boulevard

Fort Lauderdale, FL 33301-2999

T: 954 463 2700

F: 954 463 2224

September 8, 2023

Catalyst Pharmaceuticals, Inc.

355 Alhambra Circle

Suite 801

Coral Gables, FL 33134

Re:

Registration Statement on Form S-3

Ladies and Gentlemen:

We have acted as counsel to Catalyst Pharmaceuticals, Inc., a Delaware corporation (the “Company”) in connection with the preparation and filing with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended (the “Securities Act”) of a registration statement on Form S-3 (the “Registration Statement”) relating to the offering from time to time of: (i) shares of the Company’s common stock, par value $0.001 per share (the “Common Stock”); (ii) shares of the Company’s Preferred Stock, par value $0.001 per share (the “Preferred Stock”); (iii) debt securities of the Company (the “Debt Securities”); (iv) warrants to purchase the Common Stock (the “Warrants”); and (v) units consisting of debt securities, common stock, and/or warrants to purchase common stock in any combination (the “Units” and, together with the Common Stock, the Preferred Stock, the Debt Securities, and the Warrants, the “Securities”). The Securities are to be offered hereunder on a delayed or continuous basis pursuant to the provisions of Rule 415 under the Securities Act in the manner described in the Prospectus (as defined below). The aggregate public offering price of the Securities being registered will be $500,000,000.

This opinion letter is being furnished in accordance with the requirements of Section 601(b)(5) of Regulation S-K under the Securities Act.

In connection with this opinion letter, we have examined the Registration Statement, including the Prospectus contained therein (the “Prospectus”) and such corporate records, documents, instruments and certificates of public officials and of the Company that we have deemed necessary for the purpose of rendering the opinions set forth herein. We have also reviewed such matters of law as we considered necessary or appropriate as a basis for the opinions set forth below.

akerman.com

Catalyst Pharmaceuticals, Inc.

September 8, 2023

Page 2

With your permission, we have made and relied upon the following assumptions, without any investigation or inquiry by us, and our opinions expressed below are subject to, and limited and qualified by the effect of, such assumptions: (i) all corporate records furnished to us by the Company are accurate and complete; (ii) the Registration Statement filed by the Company with the Commission is identical to the form of the document that we have reviewed; (iii) all statements as to factual matters that are contained in the Registration Statement (including the exhibits to the Registration Statement) are accurate and complete; (iv) the Company will sell and issue the Securities in accordance with the manner described in the Prospectus; and (v) with respect to documents that we reviewed in connection with this opinion letter, all documents submitted to us as originals are authentic, all documents submitted to us as certified, facsimile or photostatic copies conform to the originals of such documents, all such original documents are authentic, the signatures on all documents are genuine, and all natural persons who have executed any of the documents have the legal capacity to do so.

Based on and subject to the foregoing, and subject to the further assumptions and qualifications set forth herein, we are of the opinion that:

The Company is a Delaware corporation that is validly existing and in good standing under Delaware law.

With respect to any shares of Common Stock to be offered pursuant to the Registration Statement, provided that (i) the Registration Statement and any required post-effective amendment thereto have all become effective under the Securities Act and the Prospectus and any and all prospectus supplement(s) required by applicable laws have been delivered and filed as required by such laws; (ii) the issuance of the Common Stock has been duly authorized by all necessary corporate action on the part of the Company; (iii) the issuance and sale of the Common Stock do not violate any applicable law, are in conformity with the Company’s then-operative certificate of incorporation (the “Certificate of Incorporation”) and bylaws (the “Bylaws”), do not result in a default under or breach of any agreement or instrument binding upon the Company, and comply with any applicable requirement or restriction imposed by any court or governmental body having jurisdiction over the Company; and (iv) the Common Stock has been duly delivered to the purchasers thereof against payment therefor, then the Common Stock, when issued and sold as contemplated in the Registration Statement, the Prospectus and the related prospectus supplement(s) and in accordance with any applicable duly authorized, executed and delivered purchase, underwriting or similar agreement, or upon conversion of any convertible Preferred Stock, or convertible Debt Securities in accordance with their terms, or upon exercise of any Warrants in accordance with their terms, will be validly issued, fully paid and nonassessable..

Catalyst Pharmaceuticals, Inc.

September 8, 2023

Page 3

With respect to any shares of Preferred Stock to be offered pursuant to the Registration Statement, provided that (i) the Registration Statement and any required post-effective amendment thereto have all become effective under the Securities Act and the Prospectus and any and all prospectus supplement(s) required by applicable laws have been delivered and file as required by such laws; (ii) the terms and issuance of the Preferred Stock have been duly authorized by all necessary corporate action on the part of the Company; including the adoption of any required Certificate of Designation for any shares of Preferred Stock offered under the Registration Statement (“Certificate of Designation”) in accordance with the applicable provision of the Delaware General Corporation Law (the “DGCL”); (iii) the filing of any required Certificate of Designation with the Secretary of State of the State of Delaware has occurred; (iv) the terms of the shares of Preferred Stock and their issuance and sale do not violate any applicable law, are in conformity with the Certificate of Incorporation and Bylaws, do not result in a default under or breach of any agreement or instrument binding upon the Company and comply with any applicable requirement or restriction imposed by any court or governmental body having jurisdiction over the Company; and (v) the Preferred Stock has been delivered to the purchasers thereof against payment therefor, then the Preferred Stock, when issued and sold as contemplated in the Registration Statement, the Prospectus and the related prospectus supplement(s) and in accordance with any applicable duly authorized, executed and delivered purchase, underwriting or similar agreement, or upon conversion of any convertible Debt Securities in accordance with their terms, will be validly issued, fully paid and nonassessable.

With respect to any series of the Debt Securities to be issued under the Indenture (the “Indenture”), and to be offered under the Registration Statement, provided that (i) the Registration Statement and any required post-effective amendment thereto have all become effective under the Securities Act and the Prospectus and any and all prospectus supplement(s) required by applicable laws have been delivered and filed as required by such laws; (ii) the Indenture has been duly authorized by the Company and the trustee named therein (the “Trustee”) by all necessary corporate action; (iii) the Indenture has been duly executed and delivered by the Company and the Trustee; (iv) the issuance and terms of the Debt Securities have been duly authorized by the Company by all necessary corporate action; (v) the terms of the Debt Securities and of their issuance and sale have been duly established in conformity with the Indenture so as not to violate any applicable law or result in a default under or breach of any agreement or instrument binding upon the Company, so as to be in conformity with the Certificate of Incorporation and Bylaws, and so as to comply with any requirement or restriction imposed by any court or governmental body having jurisdiction over the Company; and (vi) the Debt Securities have been duly executed and delivered by the Company and authenticated by the Trustee pursuant to the Indenture and delivered against payment therefor, then the Debt Securities, when issued and sold in accordance with the Indenture and a duly authorized, executed and delivered purchase, underwriting or similar agreement, will be valid and binding obligations of the Company, enforceable against the Company in accordance with their terms.

Catalyst Pharmaceuticals, Inc.

September 8, 2023

Page 4

With respect to the Warrants issued under a warrant agreement (the “Warrant Agreement”) and to be offered under the Registration Statement, provided that (i) the Registration Statement and any required post-effective amendment thereto have all become effective under the Securities Act and the Prospectus and any and all prospectus supplement(s) required by applicable laws have been delivered and filed as required by such laws; (ii) any applicable Warrant Agreement has been duly authorized by the Company and any warrant agent named therein (the “Warrant Agent”) by all necessary corporate action; (iii) any applicable Warrant Agreement has been duly executed and delivered by the Company and the Warrant Agent and the terms of the Warrant Agreement have been established in accordance with applicable law; (iv) the issuance and terms of the Warrants have been duly authorized by the Company by all necessary corporate action; (v) the terms of the Warrants and of their issuance and sale have been duly established in conformity with any applicable Warrant Agreement and as described in the Registration Statement, the Prospectus and the related prospectus supplement(s), so as not to violate any applicable law or result in a default under or breach of any agreement or instrument binding upon the Company, so as to be in conformity with the Certificate of Incorporation and Bylaws, and so as to comply with any requirement or restriction imposed by any court or governmental body having jurisdiction over the Company; and (vi) the Warrants have been duly executed and delivered by the Company and authenticated by any Warrant Agent pursuant to any applicable Warrant Agreement and delivered against payment therefor, then the Warrants, when issued and sold in accordance with the applicable Warrant Agreement and a duly authorized, executed and delivered purchase, underwriting or similar agreement, will be valid and binding obligations of the Company, enforceable against the Company in accordance with their terms.

With respect to the Units issued under any applicable agreement under which such Units are to be issued (a “Unit Agreement”) and offered under the Registration Statement, provided that (i) the Registration Statement and any required post-effective amendment thereto have all become effective under the Securities Act and the Prospectus and any and all prospectus supplement(s) required by applicable laws have been delivered and filed as required by such laws; (ii) any applicable Unit Agreement has been duly authorized by the Company and any other party thereto by all necessary corporate action; (iii) any applicable Unit Agreement has been duly executed and delivered by the Company and any other party thereto and the terms of the Unit Agreement, if applicable, have been established in accordance with applicable law; (iv) the issuance and terms of the Units have been duly authorized by the Company by all necessary corporate action; (v) the terms of the Units and of their issuance and sale have been duly established in conformity with any applicable Unit Agreement, if applicable, and as described in the Registration Statement, the Prospectus and the related prospectus supplement(s), so as not to violate any applicable law or result in a default under or breach of any agreement or instrument binding upon the Company, so as to be in conformity with the Certificate of Incorporation and Bylaws, and so as to comply with any requirement or restriction imposed by any court or governmental body having jurisdiction over the Company; and (vi) the Units pursuant to any applicable Unit Agreement have been duly executed and delivered by the Company and authenticated by all other parties thereto and delivered against payment therefor, then the Units, when issued and sold in accordance with the applicable Units Agreement and a duly authorized, executed and delivered purchase, underwriting or similar agreement, will be valid and legally binding obligations of the Company, enforceable against the Company in accordance with their terms.

Catalyst Pharmaceuticals, Inc.

September 8, 2023

Page 5

We express no opinion as to matters governed by laws of any jurisdiction other than the laws of the State of New York and the DGCL. We neither express nor imply any obligation with respect to any other laws or the laws of any other jurisdiction or of the United States. For purposes of this opinion, we assume that the Securities will be issued in compliance with all applicable state securities or blue sky laws.

The opinions set forth above are subject to (a) the effects of bankruptcy, insolvency, fraudulent conveyance, reorganization, moratorium and other similar laws relating to or affecting the enforcement of creditors’ rights generally, (b) general equitable principles (whether considered in a proceeding in equity or at law), (c) an implied covenant of good faith and fair dealing, (d) provisions of law that require that a judgment for money damages rendered by a court in the United States be expressed only in United States dollars, (e) limitations by any governmental authority that limit, delay or prohibit the making of payments outside the United States, and (f) generally applicable laws that (i) provide for the enforcement of oral waivers or modifications where a material change of position in reliance thereon has occurred or provide that a course of performance may operate as a waiver, (ii) limit the availability of a remedy under certain circumstances where another remedy has been elected, (iii) limit the enforceability of provisions releasing, exculpating or exempting a party from, or requiring indemnification of a party for, liability for its own action or inaction, to the extent the action or inaction involves gross negligence, recklessness, willful misconduct or unlawful conduct, (iv) may, where less than all of a contract may be unenforceable, limit the enforceability of the balance of the contract to circumstances in which the unenforceable portion is not an essential part of the agreed exchange, (v) may limit the enforceability of provisions providing for compounded interest, imposing increased interest rates or late payment charges upon delinquency in payment or default or providing for liquidated damages or for premiums upon acceleration or (vi) limit the waiver of rights under usury laws.

We assume no obligation to update or supplement this opinion letter if any applicable laws change after the date of this opinion letter or if we become aware after the date of this opinion letter of any facts, whether existing before or arising after the date hereof, that might change the opinions expressed above. This opinion letter is limited to the matters expressly stated herein and no opinions are to be inferred or may be implied beyond the opinions expressly so stated. Without limiting the generality of the foregoing, we neither express nor imply any opinion regarding the contents of the Registration Statement or the Prospectus, other than as expressly stated herein with respect to the Securities to be issued pursuant to the Registration Statement.

Catalyst Pharmaceuticals, Inc.

September 8, 2023

Page 6

This opinion letter is furnished in connection with the filing of the Registration Statement and may not be relied upon for any other purpose without our prior written consent in each instance. Further, no portion of this letter may be quoted, circulated or referred to in any other document for any other purpose without our prior written consent.

We hereby consent to the use of our name under the heading “Legal Matters” in the Registration Statement to be filed by the Company with the Commission. We further consent to your filing a copy of this opinion as Exhibit 5.1 to the Registration Statement. In giving such permission, we do not admit hereby that we come within the category of persons whose consent is required under Section 7 of the Securities Act, or the rules and regulations of the Commission thereunder.

Sincerely,

/s/ Akerman LLP

AKERMAN LLP