EXHIBIT 10.31 ADDENDUM TO EMPLOYMENT AGREEMENT DATED AUGUST 19, 1996 BETWEEN DAVID D. MUTH AND NABI Nabi --------------------------------------------------- ----------------------------- 5800 PARK OF COMMERCE BOULEVARD, N.W. BOCA RATON, FL 33487...

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                                                                   EXHIBIT 10.31







                                    ADDENDUM
                                       TO
                              EMPLOYMENT AGREEMENT
                              DATED AUGUST 19, 1996
                                     BETWEEN
                             XXXXX X. XXXX AND NABI


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Nabi
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                                           0000 XXXX XX XXXXXXXX XXXXXXXXX, X.X.
                                                           XXXX XXXXX, XX  00000



             Addendum to Employee Agreement dated August 19, 1996
                               Xx. Xxxxx X. Xxxx



Effective May 15, 1998, the above referenced Employee Agreement is hereby
amended as follows:






              Section 7 (C) ".... Nabi will pay you severance pay of twelve (12)
              months of your annual base salary..."







 /s/ Xxxxx X. Xxxx                                          5/18/98
-------------------------------                    -----------------------------
XXXXX X. XXXX                                      DATE




Approved:




/s/ Xxxxx X. Xxxx                                           5/15/98
-------------------------------                    -----------------------------
XXXXX X. XXXX                                      DATE