Press Release Details

Research Triangle Park, North Carolina - October 24, 2011 - BioCryst Pharmaceuticals, Inc. (NASDAQ:BCRX) today announced that results from its Phase 2b randomized, double-blind, dose-response study of BCX4208 in patients with gout who have failed to reach the clinically important serum uric acid (sUA) goal of <6 mg/dL on allopurinol alone have been accepted as a late-breaker oral presentation at the 2011 Annual Scientific Meeting of the American College of Rheumatology and the Association of Rheumatology Health Professionals (ACR/ARHP). The oral presentation of the study results is titled "BCX4208 Combined With Allopurinol Increases Response Rates in Patients With Gout Who Fail to Reach Goal Range Serum Urate on Allopurinol Alone: A Randomized, Double-Blind, Placebo-Controlled Trial" and is scheduled for November 8, 2011 at 2:30-4:30 p.m. Central Time (Presentation Number L10).

This Phase 2b study randomized 279 patients to five study arms: BCX4208 at doses of 5 mg, 10 mg, 20 mg, 40 mg and placebo, administered once-daily for 12-weeks. Allopurinol 300 mg once-daily was administered in all study arms. The primary study endpoint was the proportion of patients with sUA <6 mg/dL at day 85. Positive top-line results from this study were reported on October 5, 2011, announcing that the primary endpoint was successfully achieved.

BioCryst will also present results from other BCX4208 clinical and pre-clinical studies at a poster session scheduled for Monday, November 7, 2011 at 9:00 a.m.-6:00 p.m. Central Time. The two posters to be presented are:

• Presentation Number 1018: "BCX4208 Synergistically Lowers sUA Levels when Combined with Allopurinol in Patients with Gout: Results of a Phase 2 Dose-Ranging Trial"

• Presentation Number 1026: "Nonclinical Drug-Drug Interaction Profile of BCX4208, an Oral, Once-Daily, Novel Nonmetabolized Enzyme Inhibitor for Chronic Management of Gout"

Copies of the abstracts are available and can be viewed online through the ACR website at www.rheumatology.org. In accordance with the conference's embargo policy, the oral presentation and posters will be uploaded to the BioCryst website only after completion of the sessions. Please refer to the Company's BCX4208 publications page.

Conference Call and Webcast

Separate from the Scientific Meeting, BioCryst will host a conference call and webcast on Tuesday, November 8, 2011 at 7:45 p.m. Central Time to discuss the BCX4208 results presented during the meeting. To participate in the conference call, please dial 1-877-303-8027 (United States) or 1-760-536-5165 (International). No passcode is needed for the call. The webcast can be accessed by logging onto BioCryst's website at www.biocryst.com. Please connect to the website at least 15 minutes prior to the start of the conference call to ensure adequate time for any software download that may be necessary.

About Gout

Gout is a chronic inflammatory arthritis caused by monosodium urate crystal deposits in joints and the kidneys resulting from elevated serum uric acid (sUA) levels in the blood, a condition known as hyperuricemia. The consequences of gout may include intense, painful flares affecting one or more joints, impaired kidney function and joint destruction. Gout continues to grow in prevalence and severity, affecting over 17 million people in major markets, including 8.3 million in the U.S. A majority of gout patients are also treated to manage other chronic conditions, including hypertension, diabetes and/or high cholesterol. Decreasing sUA to the recommended level (less than 6 mg/dL) can reduce the risk of gout attacks over the long-term. A minority of patients treated with the current standard of care, allopurinol, achieve this therapeutic goal. There is a need for new therapies that effectively and safely get a larger portion of gout suffers to goal without the risk of drug-drug interactions. More information regarding gout and hyperuricemia is available on the CDC website at www.cdc.gov/arthritis/basics/gout.htm.

About BCX4208

BCX4208 is a novel enzyme inhibitor with the potential for once-a-day oral dosing suitable for chronic administration to treat gout. It acts upstream of xanthine oxidase in the purine metabolism pathway to reduce sUA in patients with gout and has a mechanism of action that complements xanthine oxidase inhibitors, such as allopurinol and febuxostat, in reducing uric acid production. With its unique mechanism of action, clinical activity and safety in clinical studies to date, BCX4208 is nearing the end of Phase 2 development as an add-on therapy to xanthine oxidase inhibitors to address unmet medical needs in patients with gout. To date, BCX4208 has been studied in over 500 subjects in clinical trials.

About BioCryst

BioCryst Pharmaceuticals designs, optimizes and develops novel small-molecule pharmaceuticals that block key enzymes involved in infectious diseases, inflammatory diseases and cancer. BioCryst currently has three novel late-stage compounds: peramivir, a neuraminidase inhibitor for the treatment of influenza, BCX4208, a purine nucleoside phosphorylase (PNP) inhibitor for the treatment of gout, and forodesine, an orally-available PNP inhibitor for hematological malignancies. Utilizing crystallography and structure-based drug design, BioCryst continues to discover additional compounds and to progress others through pre-clinical and early development to address the unmet medical needs of patients and physicians. For more information, please visit the Company's website at www.biocryst.com.

Forward-Looking Statements

This press release contains forward-looking statements, including statements regarding future results, performance or achievements. These statements involve known and unknown risks, uncertainties and other factors which may cause our actual results, performance or achievements to be materially different from any future results, performances or achievements expressed or implied by the forward-looking statements. These statements reflect our current views with respect to future events and are based on assumptions and subject to risks and uncertainties. Given these uncertainties, you should not place undue reliance on these forward-looking statements. Some of the factors that could affect the forward-looking statements contained herein include: that there can be no assurance that BCX4208 or our other compounds will prove effective in future clinical studies; that development and commercialization of BCX4208 or our other compounds may not be successful; that we or our licensees may not be able to enroll the required number of subjects in planned clinical trials and that such clinical trials may not be successfully completed; that BioCryst or its licensees may not commence as expected additional human clinical trials with BCX4208 or our other product candidates; that BCX4208 or our other product candidates may not receive required regulatory clearances from the FDA; that ongoing and future development may not have positive results; that we or our licensees may not be able to continue future development of our current and future development programs; that our development programs may never result in a commercial product or license or royalty payments being received by BioCryst; that BioCryst may not reach favorable agreements with potential pharmaceutical and biotechnology partners for further development of BCX4208 or our other product candidates; that our actual cash burn rate may not be consistent with our expectations; that BioCryst may not have sufficient cash to continue funding the development, manufacturing, marketing or distribution of BCX4208 or our other products and that additional funding, if necessary, may not be available at all or on terms acceptable to BioCryst. Please refer to the documents BioCryst files periodically with the Securities and Exchange Commission, specifically BioCryst's most recent Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, and current reports on Form 8-K, all of which identify important factors that could cause the actual results to differ materially from those contained in our projections and forward-looking statements.

BCRXW

CONTACT:
Robert Bennett
BioCryst Pharmaceuticals
+1-919-859-7910
(investors)

Catherine Collier Kyroulis
WCG
+1-212-301-7174
(media)