Catalyst Pharmaceuticals Announces Fourth Quarter and Year-End 2017 Financial Results and Provides Corporate Update Firdapse NDA to be Resubmitted Before the End of this Quarter Significant Progress with MuSK-MG Regulato

Catalyst Pharmaceuticals Announces Fourth Quarter and Year-End

2017 Financial Results and Provides Corporate Update

to be Resubmitted Before the End of this Quarter

Significant Progress with MuSK-MG

Regulatory and Clinical Program

$84M Year-End Cash and Investments

Company to Host Quarterly Conference Call at 5:00 pm ET Today

CORAL GABLES, Fla., March 14, 2018 (GLOBE NEWSWIRE) Catalyst Pharmaceuticals, Inc. (Nasdaq: CPRX), a

biopharmaceutical company focused on developing and commercializing innovative therapies for people with rare debilitating, chronic neuromuscular and neurological diseases, today reported financial results for the fourth quarter and

year-ended December 31, 2017.

Throughout 2017, we made significant progress in successfully completing our second Phase 3 trial evaluating

Firdapse for the treatment of Lambert-Eaton Myasthenic Syndrome (LEMS) and successfully completing the required abuse liability studies that confirmed that Firdapse does not exhibit abuse potential. We also continued to build our rare neuromuscular

disease platform as we prepared to enroll subjects in our Phase 3 clinical trial for MuSK antibody positive myasthenia gravis and our proof-of-concept clinical trial for

spinal muscular atrophy Type 3 , said Patrick J. McEnany, Chairman and Chief Executive Officer of Catalyst Pharmaceuticals, Inc. We remain on track to resubmit our NDA for Firdapse this quarter, and we are actively engaged in pre-commercialization activities for a potential launch of Firdapse.

2017 and Recent Highlights

Fourth Quarter and Full-Year 2017 Financial Results

For the year ended December 31, 2017, Catalyst reported a GAAP net loss of $18,412,377, or $0.21 per basic and diluted share, compared to a GAAP net loss

of $18,072,452, or $0.22 per basic and diluted share, for the 2016 fiscal year. Excluding non-cash loss of $186,904 attributable to the change in fair value of liability-classified warrants, Non-GAAP1 net loss was $18,225,473, or $0.21 per basic and diluted share, for the year ended December 31, 2017. In comparison,

Non-GAAP1 net loss for the year ended December 31, 2016 was $18,958,589, or $0.23 per basic and diluted share, which excludes non-cash gain of $886,137 attributable to the change in fair value of liability-classified warrants.

ended December 31, 2017, Catalyst reported a GAAP net loss of $5,387,698, or $0.06 per basic and diluted share, compared to a GAAP net loss of $4,163,320, or $0.05 per basic and diluted share, for the 2016 fiscal year. For the fourth quarter of

2017, Non-GAAP1 net loss was the same as GAAP net loss as there were no Non-GAAP1 adjustments. In comparison, Non-GAAP1 net loss for the fourth quarter of 2016 was $4,270,266, or

$0.05 per basic and diluted share, which excludes non-cash gain of $106,946 attributable to the change in fair value of liability-classified warrants.

Research and development expenses for the year ended December 31, 2017 were $11,375,237, compared to $11,369,941 for the 2016 fiscal year. For the fourth

quarter of 2017, research and development expenses were $3,404,634, compared to $2,820,654 for the fourth quarter of 2016. Research and development expenses in 2017 were consistent with amounts expended in 2016, and included expenses related to

ongoing studies and trials for Firdapse, the costs of Catalyst s Firdapse Expanded Access Program, and costs of Catalyst s CPP-115 and generic

Sabril programs. Catalyst expects that its R&D spend for 2018 will continue to be substantial as Catalyst completes its clinical trial for CMS, continues its Expanded Access Program,

continues its clinical programs for MuSK-MG and SMA Type 3, prepares the NDA submission for Firdapse, and manufactures Firdapse launch supplies.

General and administrative expenses for the year ended December 31, 2017 totaled $7,304,399, compared to $7,910,260 in the 2016 fiscal year. For the

fourth quarter of 2017, general and administrative expenses totaled $2,107,152, compared to $1,493,545 in the same period in 2016. The decrease in general and administrative expenses from 2017 to 2016 was primarily due to Catalyst s efforts to

conserve cash after the receipt of the FDA s refusal to file letter for Firdapse. Catalyst expects that general and administrative costs will increase in 2018, as Catalyst prepares for the commercialization of Firdapse.

Catalyst had no revenues in the year 2017 or 2016.

At December 31, 2017, Catalyst had cash and investments of $84 million and no debt. Based on its current financial position and its forecasts of

available cash, Catalyst believes that it has sufficient funds to support its operations through 2019 (without considering revenues and cash receipts that may be received in 2019 if Catalyst is successful in obtaining an approval of Firdapse and

launching the product in 2019, of which there can be no assurance).

More detailed financial information and analysis can be found in Catalyst s

Annual Report on Form 10-K for the fiscal year ended December 31, 2017, which was filed with the Securities and Exchange Commission, earlier today, March 14, 2018.

Catalyst management will host an

investment-community conference call and webcast at 5:00 p.m. ET, today, Wednesday, March 14, 2018 to discuss the financial results and provide a corporate update. Investors who wish to participate in the conference call may do so by

dialing (877) 407-8912 for domestic and Canadian callers or (201) 689-8059 for international callers. Those interested in listening to the conference call live via the

internet may do so by visiting the Investors page of the company s website at www.catalystpharma.com and clicking on the webcast link on the Investors home page. A webcast replay will be available on the Catalyst website for 30 days

following the call by visiting the Investor page of the company s website at www.catalystpharma.com.

About Catalyst Pharmaceuticals

Catalyst Pharmaceuticals is a biopharmaceutical company focused on developing and commercializing innovative therapies for people with rare

debilitating, chronic neuromuscular and neurological diseases, including Lambert-Eaton myasthenic syndrome (LEMS), congenital myasthenic syndromes (CMS), MuSK antibody positive myasthenia gravis, and infantile spasms. Firdapse has received Breakthrough Therapy Designation from the U.S. Food and Drug Administration (FDA) for the treatment of LEMS and Orphan Drug Designation for LEMS, CMS and myasthenia gravis. Firdapse

is the first and only approved drug in Europe for symptomatic treatment in adults with LEMS.

Catalyst is also developing

CPP-115 to treat refractory infantile spasms. CPP-115 has been granted U.S. Orphan Drug Designation for the treatment of infantile spasms by the FDA and has been granted

E.U. Orphan Medicinal Product Designation for the treatment of West syndrome by the European Commission. In addition, Catalyst is developing a generic version of Sabril (vigabatrin).

Forward-Looking Statements

contains forward-looking statements. Forward-looking statements involve known and unknown risks and uncertainties, which may cause Catalyst s actual results in future periods to differ materially from forecasted results. A number of factors,

including (i) whether the results of the LMS-003 trial, combined with the results of the Company s previous Phase 3 trial, will be acceptable to the FDA as support for an approval of Firdapse for the

treatment of LEMS, (ii) whether the results of the abuse liability studies undertaken by Catalyst will be acceptable to the FDA as support for an approval of Firdapse, (iii)

whether any NDA submitted for Firdapse will be accepted by the FDA, and the timing of any such submission and acceptance, (iv) whether the receipt of breakthrough therapy designation for

Firdapse will expedite the development and review of Firdapse by the FDA or the likelihood that the product will be found to be safe and effective, (v) whether, if an NDA for Firdapse is accepted for filing, such NDA will be given a priority

review by the FDA, (vi) whether Firdapse will ever be approved for commercialization, (vii) whether Catalyst will be the first company to receive an approval for amifampridine (3,4-DAP), giving it 5-year marketing exclusivity for its product, and (viii) those other factors described in Catalyst s Annual Report on Form 10-K for the fiscal year 2017 and its

other filings with the U.S. Securities and Exchange Commission (SEC), could adversely affect Catalyst. Copies of Catalyst s filings with the SEC are available from the SEC, may be found on Catalyst s website, or may be obtained upon

request from Catalyst. Catalyst does not undertake any obligation to update the information contained herein, which speaks only as of this date.

CATALYST PHARMACEUTICALS, INC.

CONSOLIDATED STATEMENTS OF OPERATIONS (unaudited)

CATALYST PHARMACEUTICALS, INC.

CONDENSED CONSOLIDATED BALANCE SHEETS