Cocrystal Pharma Inc. agreed to sell common shares worth about $4.2 million in a private placement to three healthcare-focused institutional investors who already hold stock in the company.

The Bothell, Wash.-based company is selling 1,602,283 common shares at $2.61 apiece and expects to close the placement on or before March 13.

Proceeds from the placement will fund research and development activities of antiviral candidates for hepatitis and influenza viruses along with noroviruses. Cocrystal will also use the funds for working capital and general corporate purposes.

Cocrystal discovers and develops antiviral therapeutics that target the replication machinery of viruses.