Conflict of interest statement: FUNDING: The preparation of this review was not 
supported by any external funding. CONFLICT OF INTEREST: During the peer review 
process the manufacturer of the agent under review was offered an opportunity to 
comment on the article. Changes resulting from any comments received were made 
by the author on the basis of scientific completeness and accuracy. A. Markham, 
a contracted employee of Adis/Springer, is responsible for the article content 
and declares no relevant conflicts of interest.