Marinus Pharmaceuticals Inc. plans to raise about $65 million in gross proceeds from a public offering of its common stock and a concurrent private placement.

The Radnor, Pa.-based pharmaceuticals company is offering 28 million shares for $1.25 each as part of its underwritten public offering. Underwriters have also been given a 30-day option to buy up to an additional 4.2 million common shares from the company, Marinus said in a Dec. 11 press release.

Meanwhile, certain investors have agreed to purchase a total of $30 million worth of preferred shares.

Net proceeds from the common stock offering and the private placement will be primarily used to further the clinical development of the company's postpartum depression drug ganaxolone, which failed to best placebo during the second part of a mid-stage clinical trial in July.

Oppenheimer & Co. Inc. and Ladenburg Thalmann & Co. Inc. were the joint book-running managers, while Craig-Hallum Capital Group LLC acted as co-manager for the offering, expected to close Dec. 13.