Characterization of flufylline, fluprofylline, ritanserin, butanserin and R 56413 with respect to in‐vivo α₁‐, α₂‐ and 5‐HT₂‐receptor antagonism and in‐vitro affinity for α₁‐, α₂‐ and 5‐HT₂‐receptors: comparison with ketanserin

The experimental drugs butanserin (R 53393), ritanserin (R 55667), R 56413, flufylline (Sgd 195/78) and fluprofylline (Sgd 144/80) were evaluated with respect to their antagonism at postjunctional α₁‐ and α₂‐adrenoceptors and 5‐HT₂‐receptors in pithed rats. Moreoever, affinity for [³H]mianserin, [³H]prazosin and [³H]yohimbine binding sites was assessed using rat brain preparations. In all experiments ketanserin was taken as a reference compound. It is concluded that of the compounds investigated butanserin is the most potent and selective α₁‐adrenoceptor antagonist, whereas ritanserin was found to be a potent and selective 5‐HT₂‐antagonist. Of the other compounds, fluprofylline was a very selective though not very potent α₁‐adrenoceptor antagonist. The other compounds were less active and less selective in this respect.