How to update Oracle Application front end user password from backend

DECLARE
   lb_status   BOOLEAN;
BEGIN
   lb_status :=
      FND_USER_PKG.CHANGEPASSWORD (
         username      => 'GIRIDHART',
         newpassword   => 'welcome12345');
   IF lb_status
   THEN
      DBMS_OUTPUT.PUT_LINE ('Request processed sucessfully');
   ELSE
      DBMS_OUTPUT.PUT_LINE ('Error while processing the request');
   END IF;
END;