With [SH] ketanserin as the radioligand, structureaffinity relationships (SAFIRs) for binding at central 5HTz serotonin receptors (rat frontal cortex) were examined for a series of 27 4- substituted 1-(2, 5dimethoxypheny1)-2-aminopropane derivatives (2, 5-DMAs). The affinity (Ki values) ranged over a span of several orders of magnitude. It appears that the lipophilic character of the 4-position substituent plays a major role in determining the affinity of these ...