Use according to claim 1 , characterised in that compounds of the formula (I) according to claim 2 , in which the radicals have the following meanings: R represents optionally substituted heteroarylmethyl, heteroarylethyl containing up to 6 ring atoms and N, O, S and in particular N as hetero atoms, A represents hydrogen and optionally substituted alkyl or alkylene containing 1-4 C atoms, it being