BioCryst Pharmaceuticals (NASDAQ:BCRX) is well on its way to raising more than $20 million to support clinical development of its drug pipeline.

The Durham company said Monday that underwriters to its public offering of common stock it launched last week have exercised in full their option to purchase an additional 600,000 shares. Including this overallotment, BioCryst expects gross proceeds of $20.2 million, before expenses.

BioCryst priced the stock offering last week. Wells Fargo Securities and JMP Securities are acting as joint book-running managers, with Noble Financial Capital Markets acting as co-manager for the proposed offering. The company said it would use proceeds from the offering to finance development of its drug candidates.

The offering followed positive phase I clinical trial results for BCX4161, a compound being studied as a treatment for the rare blood disorder hereditary angiodema, or HAE. BioCryst said in filings that it expects to use net proceeds to pay for clinical development of BCX4161 and to continue development of a second-generation HAE compound. BioCryst will also apply the money toward pre-commercialization work for intravenous influenza treatment peramivir. BioCryst said last month it plans to file a peramivir new drug application with the FDA by the end of the year.

The BioCryst stock offering, including the sale of the additional shares, is expected to close on Aug. 6.