n n diethylaminoethoxy phenyl 001 2 butylbenzofur 3 yl methanol hydrochloride2 methyl 3 3 5 diiodo 4 2 n n diethylamino 003 ethoxy benzoyl benzofuran hydrochloride2 n butyl 3 3 5 diiodo 4 carboxymethoxy 005 benzoyl benzofuran2 methyl 3 3 5 diiodo 4 hydroxy benzoyl benzofuran 011 2 methyl 3 3 5 diiodo 4 carboxymethoxy 015 benzyl benzofuran4 39 hydroxy 3 39 iodo 3 5 diiodo 4 2 n n dimethylamino 024 ethoxy benzophenon hydrochloride2 butyl 3 3 iodo 4 hydroxybenzoyl benzofuran 029 4 39 4 dihydroxy 3 39 3 5 triiodo diphenylmethan 032 ______________________________________ in one embodiment of this aspect of the invention the above compounds are used for the treatment of at least one of heart arrhythmia and hyperthyroidism yet another aspect of the invention is directed to a pharmaceutical preparation which comprises as an active ingredient a compound selected from the group consisting of ______________________________________3 5 diiodo 4 2 n n diethylaminoethoxy phenyl 001 2 butylbenzofur 3 yl methanol hydrochloride2 methyl 3 3 5 diiodo 4 2 n n diethylamino 003 ethoxy benzoyl benzofuran hydrochloride2 n butyl 3 3 5 diiodo 4 carboxymethoxy 005 benzoyl benzofuran2 methyl 3 3 5 diiodo 4 hydroxy benzoyl benzofuran 011 2 methyl 3 3 5 diiodo 4 carboxymethoxy 015 benzyl benzofuran4 39 hydroxy 3 39 iodo 3 5 diiodo 4 2 n n dimethylamino 024 ethoxy benzophenon hydrochloride2 butyl 3 3 iodo 4 hydroxybenzoyl benzofuran 029 4 39 4 dihydroxy 3 39.