BOSTON, MA—August 19, 2002—MDL Information Systems, Inc. (MDL^®), Derwent Information, and ISI^® announced that they are collaborating to index chemical structures in selected Derwent and ISI patent and chemical information databases into DiscoveryGate^SM—MDL's Web-based service that integrates, indexes, and links the essential content sources required for effective drug discovery. The first phase of this new, expanded scientific information resource will be available to researchers during 2002.

"This critical link between DiscoveryGate and selected Derwent and ISI databases will streamline scientific inquiry and accelerate the discovery process," said MDL President and CEO Pat Rougeau. "Customer feedback indicated that access to current patent information is crucial to researchers. This important collaboration makes DiscoveryGate the complete knowledge navigation solution for chemistry and life science researchers around the world—and the first place to go for the answers to discovery questions."

Indexing and linking Derwent and ISI databases in DiscoveryGate means that researchers can perform single-query searches within DiscoveryGate to explore published information on particular compounds, including available patent listings, and then link to Derwent Discovery™ or to Derwent or ISI databases available in-house under MDL^® ISIS for details. Derwent and ISI sources in DiscoveryGate include:

• Derwent Chemistry Resource—Valuable index of specific structures designed to aid in searching chemical content of Derwent World Patents Index^®. The Derwent World Patents Index is the world's most comprehensive database of value-added patent documents, currently containing 11 million unique patent records with an additional 1.5 million patent documents added every year from 40 patent-issuing authorities.
  
• Derwent Journal of Synthetic Methods (DJSM)—Concise, synthetic organic chemical reaction data including over 75,000 novel synthetic methods and new reactions reported in over 130 primary chemical journals and the patent literature
  
• Derwent World Drug Index—Authoritative index for marketed and development drugs, containing chemical, biomedical, and synonym data for over 77,000 drugs worldwide
  
• Derwent World Drug Alerts—Up-to-date information on biologically-active compounds, drug synthesis, and pharmaceutics; covers articles from 1,200 scientific and medical journals, conference reports, and patents from seven major patent-issuing authorities
  
• Index Chemicus^®—ISI^® text- and substructure-searchable database, reporting over 200,000 new compounds each year, with coverage of over one million structures published in the literature since 1991
  
• Current Chemical Reactions^® (CCR^®) —ISI^® database covering synthetic methods reported in the world's leading synthetic chemistry journals and providing access to over 400,000 reactions

"The world's top companies depend on Derwent's scientific and patent information to stay on top of the latest developments in today's fast moving markets," said Mike Tansey, president and CEO of Thomson Scientific. "Making selected Derwent and ISI databases available through DiscoveryGate is an effective way to get critical information to researchers' desktops in an accessible, easy-to-use, Web-based environment."

When researchers locate compounds in a Derwent or ISI database, they can link to DiscoveryGate to explore the physical properties of the compounds, pertinent metabolism or toxicology studies, preparations to make the compounds, and commercial suppliers. MDL's DiscoveryGate indexes more than 11 million structures and provides easy links to access associated reactions and over 200 million facts from the following databases:

• CrossFire Beilstein
  
• MDL® Available Chemicals Directory
  
• ChemInform Reaction Library
  
• MDL® Drug Data Report
  
• MDL® Metabolite Database
  
• MDL® Toxicity Database
  
• MDL® Screening Compounds Directory
  
• MDL® Solid-Phase Organic Reactions
  
• MDL® Comprehensive Medicinal Chemistry
  
• Current Synthetic Methodology
  
• MDL® ORGSYN Database
  
• MDL® Reference Library of Synthetic Methodology
  
• National Cancer Institute Database
  
• AIDS Database

Derwent Information is the world's leading patent and scientific information provider. Derwent helps top life science and chemical companies stay ahead of their competitors by providing them with key technical, scientific, and business information drawn from patents, research journals, and conference proceedings. Derwent products, including the unrivalled Derwent Discovery™, Derwent GENESEQ™, and Derwent World Patents Index^®), are invaluable for monitoring competitor activity, saving R&D resources, keeping up-to-date with trends, generating new revenue sources, and managing patent portfolios. Derwent is part of The Thomson Corporation. For more information about Derwent, visit www.derwent.co.uk.

Headquartered in Philadelphia, Pennsylvania, USA with offices worldwide, ISI provides essential, high quality Web-based information to over seven million researchers, information specialists, and administrators in diverse fields. ISI is part of The Thomson Corporation. For more information about ISI, visit www.isinet.com.

The Thomson Corporation, with 2001 revenues of $7.2 billion, is a global leader in providing integrated information solutions to business and professional customers. Thomson provides value-added information, software applications and tools to more than 20 million users in the fields of law, tax, accounting, financial services, higher education, reference information, corporate training and assessment, scientific research and healthcare. The Corporation's common shares are listed on the New York and Toronto Stock Exchanges (NYSE: TOC; TSX: TOC). For more information about The Thomson Corporation, visit www.thomson.com.

Over 1,000 life science companies supercharge their discovery engines with MDL software solutions to generate fresh ideas and make breakthrough discoveries. By synchronizing and streamlining the sharing and management of vital information and knowledge, we enable scientists to work more efficiently and invent drugs faster. This saves time, money, and lives. In support of our customers and the momentous challenges they face, everything we do must be reliable, resourceful, innovative, and insightful. We are an international business headquartered in San Leandro, CA with offices worldwide. MDL is a wholly owned subsidiary of Elsevier Science, Inc., which is part of the Reed Elsevier Group plc, owned by Reed Elsevier PLC (NYSE: RUK) and Reed Elsevier NV (NYSE: ENL). For more information, visit www.mdl.com.