Marinus Pharmaceuticals Raises $20 Million in Series B Financing
Company to Advance Ganaxolone Program for the Treatment of Epilepsy

Branford, Conn. – April 10, 2009 – Marinus Pharmaceuticals, Inc. a developer of drugs to treat serious neurological and psychiatric disorders today announced the close of a $20 million Series B financing. The funding comes on the heels of the Company's recent announcement of positive Phase 2a data for ganaxolone as an adjunctive therapy in adults with partial onset seizures. The Series B financing included participation from all of Marinus' existing investors, including Canaan Partners, Domain Associates, Sofinnova Ventures and Foundation Medical Partners.

"We've made tremendous strides since our Series A financing, with the completion of two Phase 2a clinical trials for ganaxolone in two separate indications, significant patent applications to protect our intellectual property, and advances on formulations which resulted in novel IP and a strong commercial candidate," said John Krayacich, president and CEO of Marinus Pharmaceuticals. "In light of this challenging environment, the continued support from our syndicate of premier life sciences investors validates our efforts, reinforces our accomplishments, and allows us to further advance this unique therapy which we hope will provide an additional alternative for people with epilepsy."

The funding will advance the Company's ganaxolone development program for use as a novel adjunctive agent for the treatment of refractory partial seizures and to explore proof of concept studies in psychiatric indications. Marinus Pharmaceuticals has raised a total of $50 million in private financing to date.

"The management team brings proven and distinctive expertise in developing CNS therapies," said Stephen Bloch, M.D., Partner at Canaan Partners and Chairman of Marinus Pharmaceuticals. "Marinus has made significant advances with this novel first in class neuroactive steroid as an antiepileptic drug and will address significant unmet medical needs for patients with epilepsy. We are very excited about the future prospects for Marinus."

About Ganaxolone
Ganaxolone is a synthetic neurosteroid and a derivative of the naturally occurring neuromodulator, allopregnanolone. It is being investigated as a first in class treatment for epilepsy. Ganaxolone has been administered to more than 950 healthy adult volunteers and patients in more than 35 Phase 1 and Phase 2 studies. Early epilepsy studies involved more than 100 patients and generated data supportive of the efficacy and safety of ganaxolone in the treatment of both children and adults suffering from refractory epilepsy (patients who continue to have seizures despite taking multiple anticonvulsant drugs).

Marinus has successfully developed several proprietary and novel patented formulations of ganaxolone.

About Marinus Pharmaceuticals
Marinus is a specialty pharmaceutical company dedicated to the reformulation, development, and commercialization of novel drugs to treat serious neurological, psychiatric, and pain disorders. Marinus is located in Branford, Connecticut. Its investors include Domain Associates, Canaan Partners, Sofinnova Ventures and Foundation Medical Partners. For additional information, please visit the company's Web site at www.marinuspharma.com.

About Domain Associates
Founded in 1985, Domain Associates, L.L.C. is a venture capital firm with an exclusive focus on life sciences. With $2 billion of capital under management, Domain is headquartered in Princeton, NJ with a second office in San Diego, CA. Domain's three major investment segments are pharmaceuticals, specialty pharmaceuticals, and medical devices, while additional areas of interest include biomaterials, bioinstrumentation, and diagnostics. The Partners of Domain have a total of close to 200 person-years of experience among them in the healthcare/venture capital industries and have been involved in the formation and growth of more than 200 life-sciences companies. The highly focused network, experience, and reputation of this team have made it one of the top private-equity groups participating in the healthcare field. For more information, visit www.domainvc.com.

About Sofinnova Ventures
Founded in 1974, Sofinnova Ventures is a venture capital firm specializing in corporate spin-outs with over $1B under management. The firm emphasizes a diversified investment strategy through the financing of early-stage companies in the life science and information technology sectors. Sofinnova Ventures' mission is to create value by providing entrepreneurs with the resources, experience and networks necessary to turn their ideas into profitable businesses. The firm has offices in San Francisco, Menlo Park and San Diego, California. For more information, visit www.sofinnova.com

About Canaan Partners
Canaan Partners invests in visionary entrepreneurs and provides them the networks, insights and operational guidance required to build high-performance technology and healthcare companies. For 20 years, they have taken an active and committed role in the companies in which they invest, and have completed more than 72 mergers and acquisitions and 53 IPOs. With $3 billion under management and a worldwide footprint, the firm's technology team is committed to catalyzing the growth of innovative companies in the digital media, communications & mobility, enterprise and clean tech industries. Among its successes are Acme Packet, Amicus Therapeutics, Cerexa Inc., CommerceOne, DexCom Inc., DoubleClick, IntraLinks, Match.com, SuccessFactors and WebLoyalty. Other Canaan investments include Active Networks, AdvancedBioHealing, BharatMatrimony, BiPar Sciences, Blurb, Chimerix, Inc., N-trig, Prime Sense, ReVision Optics, Inc., Transoma Medical, Inc, Tremor Media and Xirrus. Canaan has offices in California, Connecticut, India and Israel. For more information, visit www.canaan.com.

About Foundation Medical Partners
Foundation Medical Partners is a leading national, independent, healthcare venture capital investment firm. Foundation was formed in 2001 with the vision of bringing together cutting edge life science expertise with deep company-building experience. Foundation specializes in early stage investments in the medical device, biopharmaceutical, and predictive medicine technology sectors. Foundation is an active venture investor, providing leadership, support, and strategic resources at every stage in a company's development. Foundation Medical Partners invests in ventures that demonstrate the capability to improve the practice of medicine and human health. For more information, visit www.foundmed.com.