Catalyst Pharmaceuticals Announces First Quarter 2018 Financial Results and Provides Corporate Update Company to Host Quarterly Conference Call at 8:30 am ET Tomorrow

Catalyst Pharmaceuticals Announces First Quarter 2018 Financial Results and Provides Corporate Update

Company to Host Quarterly Conference Call at 8:30 am ET Tomorrow

CORAL GABLES, Fla., May 9, 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 first quarter ended March 31, 2018 and

provided a corporate update.

We are pleased to continue to deliver on our key objectives for 2018, recently marked with the resubmission of our New

Drug Application of Firdapse for the symptomatic treatment of Lambert-Eaton myasthenic syndrome (LEMS), said Patrick J. McEnany, Chairman and Chief Executive Officer of Catalyst

Pharmaceuticals. With a positive Type C meeting in the first quarter, we are confident that our NDA resubmission for Firdapse includes all that is required to be accepted for review by the FDA. We are working diligently on the development of

our comprehensive patient services program, which is part of our commitment to the LEMS community. This program will have, among other features, a personalized program that provides patient and physician education, assistance with access, and

treatment support for patients and their caregivers. Lastly, we continue to make progress in the clinic for the other potential indications that we are pursuing with Firdapse. I look forward to providing updates on our progress throughout the

Q1-18 and Recent Highlights

For the quarter ended March 31, 2018, Catalyst reported a GAAP net loss of $5,699,892, or $0.06 per basic and diluted share, compared to a

GAAP net loss of $4,967,129, or $0.06 per basic and diluted share, for the same period in 2017. For the first quarter of 2018,

Non-GAAP1 net loss was the same as GAAP net loss as there were no Non-GAAP1 adjustments. Non-GAAP1 net loss for the first quarter of 2017

was $4,569,894, or $0.06 per basic and diluted share, which excludes non-cash loss of $397,235 attributable to the change in fair value of liability-classified warrants.

Research and development expenses for the first quarter of 2018 were $3,259,042 compared to $2,813,929 in the first quarter of 2017. The

increase in research and development expenses for the first three months of 2018 was primarily due to consulting expenses as we prepared to submit our NDA for Firdapse for the treatment of LEMS during March 2018, offset by a decrease in clinical

expenses, including related drug costs. The Company expects that costs related to research and development activities will continue to be substantial throughout 2018 as it continues its on-going clinical

studies and Expanded Access Program for Firdapse.

General and administrative expenses for the first quarter of 2018 totaled $2,674,398 as

compared to $1,865,942 in the first quarter of 2017. The increase when compared to the same period in 2017 is primarily due to increased pre-commercialization expenses. The Company expects general

and administrative expenses, including pre-commercialization expenses, to increase in 2018 as we expand our operations and headcount to build up our infrastructure and commercial programs in preparation for a

potential Firdapse launch in 2019.

As a development-stage biopharmaceutical company, Catalyst had no revenues in either the first quarter of 2018 and

At March 31, 2018, Catalyst had cash and cash equivalents and short-term investments of $77.9 million and no debt. Catalyst believes

that its existing capital resources will be sufficient to support its planned operations through 2019 (without considering revenues and cash receipts that may be received in 2019 if Catalyst is successful in obtaining and approval of Firdapse and

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

More detailed financial information and analysis may be found in the Company s

Quarterly Report on Form 10-Q, which was filed with the Securities and Exchange Commission (SEC) on May 9, 2018.

1 Statements made in this press release include a non-GAAP

financial measure. Such information is provided as additional information and not as an alternative to Catalyst s financial statements presented in accordance with U.S. generally accepted accounting principles (GAAP). This non-GAAP financial measure is intended to enhance an overall understanding of Catalyst s current financial performance. Catalyst believes that the non-GAAP financial

measure presented in this press release provides investors and prospective investors with an alternative method for assessing Catalyst s operating results in a manner that Catalyst believes is focused on the performance of ongoing operations

and provides a more consistent basis for comparison between periods. The non-GAAP financial measure in this press release excludes from the calculation of net loss the expense (or the income) associated with

the change in fair value of the liability-classified warrants. Non-GAAP net loss per share is calculated by dividing non-GAAP net loss by the weighted average

common shares outstanding.

Catalyst management will host an investment-community conference call and webcast at 8:30 a.m. ET, tomorrow, Thursday, May 10, 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

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 the NDA submitted for Firdapse will be accepted by the

FDA, and the timing of any such 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

CATALYST PHARMACEUTICALS, INC.

CONSOLIDATED STATEMENTS OF OPERATIONS (unaudited)

CATALYST PHARMACEUTICALS, INC.

CONDENSED CONSOLIDATED BALANCE SHEETS