1 EXHIBIT 23.1 CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS As independent public accountants, we hereby consent to the incorporation by reference in this registration statement (File No. 333-53108) of our report dated April 11, 2000 included in NeoTherapeutics, Inc.'s Form 10-K for the year ended December 31, 1999 and to all references to our Firm included in this registration statement. /s/ ARTHUR ANDERSEN LLP Orange County, California January 23, 2001