Sonus Pharmaceuticals Presents Preclinical Data on Novel Camptothecin Compound at AACR-NCI-EORTC Cancer Conference.

BOTHELL, Wash. -- Sonus Pharmaceuticals, Inc. (NASDAQ:SNUS) today presented encouraging preclinical data on its novel camptothecin-based product candidate, SN2310 Emulsion, at the AACR-NCI-EORTC cancer conference. Based on animal models, administration of an emulsion containing SN2310, a new camptothecin derivative, demonstrated improved anti-tumor activity when compared to irinotecan. In addition, these studies suggest that this formulation of SN2310 may allow less frequent dosing than irinotecan, while maintaining the therapeutic effect.

"We are pleased that the development of SN2310 Emulsion is continuing to show promise. Since initiating a Phase 3 pivotal study this year for our lead oncology candidate, TOCOSOL(R) Paclitaxel, and partnering with Schering AG to develop and commercialize that product, we are ideally positioned to move a second drug into clinical studies," said Michael A. Martino, president and chief executive officer of Sonus Pharmaceuticals. "Based on the ongoing strength of the preclinical data, our goal is to work with the FDA to move the SN2310 formulation into the first human studies in 2006."

The AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics is being held November 14-18 in Philadelphia. The SN2310 abstract presented at the conference can be accessed on Sonus' web site at www.sonuspharma.com.

About SN2310 (Camptothecin Derivative)

Camptothecins are among the most important classes of anti-cancer drugs introduced in recent years. Two products containing camptothecin derivatives, topotecan and irinotecan, are commercially available for the treatment of colorectal, lung and ovarian cancers. Due to limited circulating half-life of these camptothecin derivatives, it is believed that an alternative camptothecin-based product that offers sustained exposure in the body may be optimal for enhancing anti-tumor activity. Formulated with Sonus' TOCOSOL technology, SN2310 Emulsion is intended to provide prolonged exposure to a novel camptothecin derivative (SN2310), for improved efficacy, while minimizing unwanted toxicities.

About Sonus Pharmaceuticals

Headquartered near Seattle, Sonus Pharmaceuticals is focused on the development of novel drugs for the oncology market that may offer improved administration, tolerability, safety and effectiveness. The Company's lead product candidate is TOCOSOL Paclitaxel, a new formulation of the widely prescribed anti-cancer drug paclitaxel. TOCOSOL Paclitaxel has shown promising safety and anti-tumor activity in Phase 2 clinical trials in a variety of solid tumors, including breast, lung, ovarian and bladder cancers, and the product is currently in a Phase 3 pivotal study for the potential treatment of metastatic breast cancer. Sonus recently announced the signing of a development and commercialization agreement for TOCOSOL Paclitaxel with Schering AG, a worldwide leader in the pharmaceutical industry. For additional information on Sonus, including news releases, please visit www.sonuspharma.com.

Safe Harbor 

Certain statements made in this press release are forward-looking such as those, among others, relating to the development, safety and efficacy of drug delivery products and potential applications for these products. As discussed in Sonus Pharmaceuticals' filings with the Securities and Exchange Commission, including its Annual Report on Form 10-K filed on March 23, 2005 and Quarterly Form 10-Qs for 2005, actual results could differ materially from those projected in the forward-looking statements as a result of the following factors, among others: the Company's products will require extensive clinical testing and approval by regulatory authorities; such approvals are lengthy and expensive and may never occur; risks that the Company will not be able to complete the Phase 3 clinical trial for TOCOSOL Paclitaxel; risks that clinical studies with TOCOSOL Paclitaxel will not be successful; risks that the FDA may not approve the Company's proposed New Drug Application; risks of successful development of additional drug delivery products; risks that the Company may not be successful in obtaining funding from third parties or completing a financing necessary to support the costs and expenses of clinical studies as well as research and development activities; and risks that the Company will not obtain regulatory clearance of the license agreement with Schering AG under the Hart-Scott-Rodino Antitrust Improvements Act. The Company undertakes no obligation to update the forward-looking statements contained herein or to reflect events or circumstances occurring after the date hereof.