Evaluating the effects of an alpha-2 adrenoceptor antagonist on erectile function in the human male. 2. The erectile response to erotic stimuli in men with erectile dysfunction, in relation to age and in comparison with normal volunteers.

The effect of a new alpha-2 adrenoceptor antagonist on erectile function was assessed in 24 men with probable psychogenic erectile dysfunction. The drug was given in two dosages, together with placebo, by intravenous infusion in a balanced cross over design. Once plasma levels were established, erectile, subjective and haemodynamic responses to erotic fantasy and films were measured. Subjects were divided into two age groups, "Younger" (i.e. less than 45 years) and "Older" (greater than 45 years). There was a significant though modest increase in the duration of erectile response with the high dose of the drug, but only in the younger men. There were also drug effects on haemodynamic responses confined to the younger men, who showed markedly reduced responses during placebo administration when compared with the older dysfunctional men and with young "functional" volunteers. The findings raise the possibility that in younger men with psychogenic erectile failure, there is an inhibition of general arousal responses to erotic stimuli which is partially reversed by this drug. In the older men, the different pattern of response suggests that a) there may be a decline in response to the drug with age and b) other age-related factors are playing an important part in the aetiology of their erectile failure.