1 Exhibit H JOINT FILING AGREEMENT We, the undersigned, hereby express our agreement that the attached Amendment No. 2 to a statement on Schedule 13D for the event dated February 23, 1996, is filed on behalf of each of the undersigned. Date: March 13,...

   1
                                                                       Exhibit H
                             JOINT FILING AGREEMENT


        We, the undersigned, hereby express our agreement that the attached
Amendment No. 2 to a statement on Schedule 13D for the event dated February
23, 1996, is filed on behalf of each of the undersigned.

Date:   March 13, 1996


                                   BB BIOTECH AG
                                   
                                   By:  /s/ Xxxxxx Xxxxxxxxx                  
                                        ------------------------------------
                                   Name:    Xxxxxx Xxxxxxxxx
                                   Title:   Counsel
                                   
                                   By:  /s/ Xx. Xxxxx Xxxxxxx-Xxxxx   
                                        ------------------------------------
                                   Name:    Xx. Xxxxx Xxxxxxx-Xxxxx
                                   
                                   
                                   
                                   BIOTECH INVEST, S.A.
                                   
                                   By:  /s/ Xxxxxx Xxxxxxxxx                  
                                        ------------------------------------
                                   Name:    Xxxxxx Xxxxxxxxx
                                   Title:   Counsel
                                   
                                   
                                   
                                   BIOTECH FOCUS, S.A.
                                   
                                   By:  /s/ Xxxxxx Xxxxxxxxx                  
                                        ------------------------------------
                                   Name:    Xxxxxx Xxxxxxxxx
                                   Title:   Counsel
                                   
                                   
                                   
                                   BIOTECH TARGET, S.A.
                                   
                                   By:  /s/ Xxxxxx Xxxxxxxxx                  
                                        ------------------------------------
                                   Name:    Xxxxxx Xxxxxxxxx
                                   Title:   Counsel