function update_drugbox(drug_num, mode)

global handles

if (mode==2)
  return
end

drughandle=str_eval(['handles.drug' int2str(drug_num)]);
cbox=drughandle.concbox;
v=get(drughandle.concbox,'Value');

if (v==0)
  set_drug(drug_num, 0, -1);
elseif (v==100)
  set_drug(drug_num, v, drughandle.xmax);
else
  x_val=max((100*drughandle.ic50)/(100-v)-drughandle.ic50,drughandle.xmin);
  set_drug(drug_num, v, x_val);
end
indicate_drugs_active;