Subgroup Analyses of Pivotal and Open Label Prevention Trials Showed Effectiveness of ViroPharma's Cinryze® (C1 Esterase Inhibitor [Human]) in Prevention of Angioedema Attacks in Patients with Hereditary Angioedema (HAE) Poorly Controlled on Anabolic Androgens

- Oral Presentation at the 8th C1 Inhibitor Deficiency Workshop -

EXTON, Pennsylvania, May 28, 2013 /PRNewswire/ -- ViroPharma Incorporated (Nasdaq: VPHM), an international biopharmaceutical company committed to developing and commercializing innovative products that address unmet medical needs and rare diseases, today announced results of new data analyses from the randomized, placebo-controlled and open label clinical trials of Cinryze® (C1 esterase inhibitor [human]), the first and only C1 esterase inhibitor therapy approved for routine prevention of angioedema attacks in patients with HAE. Since neither of these clinical trials excluded patients who were on anabolic androgens (AA; attenuated androgens), analyses were conducted to evaluate how the use of AA impacted the outcome of subjects while on Cinryze.

In the randomized, placebo-controlled trial, 36.4 percent of subjects (8 of 22) were using AA for prophylaxis with a mean historical attack rate of 13.88 per 12 weeks. Five of these eight patients discontinued AA use prior to randomization. Among these five, the mean number of attacks over the 12-week placebo period was 15, compared to 6.8 attacks during the Cinryze treatment period; this represents a 54.7 percent decrease in attack rate which is similar to the reduction in attack rate (52 percent) from the overall study population.

In the open label study, 28.8 percent of subjects (42 of 146) were using AA for prophylaxis at screening and 23 of them discontinued AA during the study. The median number of attacks/month in subjects who discontinued AA was 3.00 (1.25, 11; interquartile range, IQR) at study entry which decreased to 0.00 (0.00, 0.31) during an average of 257 days in the study while taking Cinryze. Eight subjects continued on a stable dose of AA during open label treatment. The attack frequency/month of those subjects went from 3.5 (2.75, 4) at study entry to 0.26 (0.06, 0.71) after treatment with open label Cinryze. The other 11 subjects reduced but did not stop using AA; their median monthly attack frequency went from 2 (2, 3) to 0.24 (0, 0.67) at study completion. No drug interaction studies of Cinryze and AA have been conducted.

Lead author Bruce L. Zuraw, Professor of Medicine, Chief of the Section of Allergy and Immunology, and Director of the Allergy and Immunology Training Program at the University of California School of Medicine, San Diego delivered these findings during an oral platform presentation at the 8^th C1 Inhibitor Deficiency Workshop in Budapest, Hungary.

"While clinical trials have demonstrated the efficacy and safety of Cinryze for the long-term prevention of HAE, these data demonstrate that Cinryze is an important option, even in patients who have been managed on anabolic androgens and continue to experience multiple attacks of HAE," said Dr. Zuraw. "It reinforces current evidence based guidelines for the management of HAE, especially given the long-term risk/benefit of anabolic androgens."

The abstract 'Anabolic androgen experience and response to CINRYZE (C1 esterase inhibitor [human]) in the prevention trials in patients with HAE' will be published in the May edition of The Journal of Angioedema.

About Cinryze® (C1 esterase inhibitor [human])
Cinryze is a highly purified, pasteurized and nanofiltered plasma-derived C1 esterase inhibitor product. In the U.S., Cinryze is approved by the FDA for routine prophylaxis against angioedema attacks in adolescent and adult patients with HAE. In the E.U., the product is approved by the EMA for the treatment and pre-procedure prevention of angioedema attacks in adults and adolescents with hereditary angioedema (HAE), and routine prevention of angioedema attacks in adults and adolescents with severe and recurrent attacks of hereditary angioedema (HAE), who are intolerant to or insufficiently protected by oral prevention treatments or patients who are inadequately managed with repeated acute treatment. Cinryze is for intravenous use only.

Severe hypersensitivity reactions to Cinryze may occur. Thrombotic events have occurred in patients receiving Cinryze, and in patients receiving off-label high dose C1 inhibitor therapy. Monitor patients with known risk factors for thrombotic events. With any blood or plasma derived product, there may be a risk of transmission of infectious agents, e.g. viruses and, theoretically, the CJD agent. The risk has been reduced by screening donors for prior exposure to certain virus infections and by manufacturing steps to reduce the risk of viral transmission including pasteurization and nanofiltration.

The most common adverse reactions in clinical trials associated with Cinryze were rash, headache, nausea, erythema, phlebitis and local reactions at the injection site. Adverse events of sinusitis and upper respiratory infection also were observed in clinical trials. No drug-related serious adverse events (SAEs) were reported in clinical trials.

Please visit http://www.viropharma.com/products/cinryze.aspx for the full U.S. Prescribing Information; the prescribing information for other countries can be found at www.viropharma.com.

About Hereditary Angioedema (HAE)
HAE is a rare, severely debilitating, life-threatening genetic disorder caused by a deficiency of C1 inhibitor, a human plasma protein. This condition is the result of a defect in the gene controlling the synthesis of C1 inhibitor. C1 inhibitor maintains the natural regulation of the contact, complement, and fibrinolytic systems, that when left unregulated, can initiate or perpetuate an attack by consuming the already low levels of endogenous C1 inhibitor in HAE patients. Patients with C1 inhibitor deficiency experience recurrent, unpredictable, debilitating, and potentially life threatening attacks of inflammation affecting the larynx, abdomen, face, extremities and urogenital tract. Patients with HAE experience approximately 20 to 100 days of incapacitation per year. There are estimated to be at least 6,500 people with HAE in the United States and at least 10,000 people in the European Union.

For more information on HAE, visit the U.S. HAE Association's website at www.haea.org and the HAEi's (International Patient Organization for C1 Inhibitor Deficiencies) website at www.haei.org.

About ViroPharma Incorporated
ViroPharma Incorporated is an international biopharmaceutical company committed to developing and commercializing novel solutions for physician specialists to address unmet medical needs of patients living with diseases that have few if any clinical therapeutic options. ViroPharma is developing a portfolio of therapeutics for rare and Orphan diseases including C1 esterase inhibitor deficiency, Friedreich's Ataxia, and adrenal insufficiency; and recurrent C. difficile infection (CDI). Our goal is to provide rewarding careers to employees, to create new standards of care in the way serious diseases are treated, and to build international partnerships with the patients, advocates, and health care professionals we serve. ViroPharma's commercial products address diseases including hereditary angioedema (HAE), seizures and C. difficile-associated diarrhea (CDAD); for full U.S. prescribing information on our products, please download the package inserts at http://www.viropharma.com/Products.aspx; the prescribing information for other countries can be found at www.viropharma.com.

ViroPharma routinely posts information, including press releases, which may be important to investors in the investor relations and media sections of our company's web site, www.viropharma.com. The company encourages investors to consult these sections for more information on ViroPharma and our business.

Forward Looking Statements
Certain statements in this press release contain forward-looking statements that involve a number of risks and uncertainties. Forward-looking statements provide our current expectations or forecasts of future events. Forward-looking statements in this press release include statements regarding the therapeutic use and effectiveness of Cinryze in patients on anabolic androgens. Our actual results could differ materially from those results expressed in, or implied by, these forward-looking statements. The commercialization of pharmaceutical products is subject to risks and uncertainties. The data that were discussed in this presentation and The Journal of Angioedema article are subject to different interpretations and may not be predictive of the results of any individual's results or of how Cinryze performs in commercial usage. These factors, and other factors, including, but not limited to those described in our annual report on Form 10-K for the year ended December 31, 2012 and 10-Q for the quarter ended March 31, 2013 filed with the Securities and Exchange Commission, could cause future results to differ materially from the expectations expressed in this press release. The forward-looking statements contained in this press release are made as of the date hereof and may become outdated over time. ViroPharma does not assume any responsibility for updating any forward-looking statements. These forward looking statements should not be relied upon as representing our assessments as of any date subsequent to the date of this press release.