Drug developer Nastech Pharmaceutical Co. said Thursday it will raise up to $42.9 million in a public offering of 3.25 million of its common shares, priced at about $13.20 per share.

All of the shares are being sold by Nastech. The purchase price represents a 6 percent discount to Wednesday's closing price of $14.06 on the Nasdaq.

The company gave underwriters the option to buy an additional 487,500 shares to cover any over-allotments.

UBS Investment Bank is the sole bookrunner of the offering.