SANTA FE, N.M. — Men with premature ejaculation appear to have weaker erections and abnormal heart-rate responses in addition to their shortened ejaculatory latency, according to a study presented by Wendi L. Tai at the annual meeting of the Society for Psychophysiological Research.
Clomipramine, which delays ejaculation, also results in more normal penile and heart-rate responses, said Ms. Tai, who worked with David L. Rowland, Ph.D., of Valparaiso (Ind.) University on the study. Ms. Tai is currently at Indiana University, Bloomington.
The double-blind, placebo-controlled study involved 33 men with previously identified premature ejaculation (PE), along with 12 control subjects. The men viewed an erotic film and experienced vibrotactile stimulation 4–6 hours after taking clomipramine or placebo.
When taking placebo, control subjects achieved a full erection in about 4.5 minutes and maintained that erection for the entire 9 minutes of the session. Men with PE, however, reached a significantly smaller penile circumference 2.5 minutes into the session.
Some of the men with PE ejaculated between 2.5 and 4 minutes into the session, but even among the men who maintained their erections for the full 9 minutes, erections were significantly weaker than those of controls. Despite that, the investigators found no evidence that the men with PE had any significant differences in maximal erect penis size, compared with that of the control subjects.
On placebo, control subjects had a heart-rate decrease of about 4 beats/min during the session, whereas men with PE had a heart-rate increase of 2 beats/min.
The erectile and heart-rate responses of men with PE and controls were more alike when they took clomipramine, known to retard ejaculation. Although some men with PE did ejaculate early, those who did not had as strong a penile response as the control subjects—significantly stronger than with placebo. The control subjects had just as strong an erection with clomipramine as with placebo.
Likewise, men with PE and controls did not have significantly different heart-rate responses. Both groups had a heart-rate decrease between 0 and 1 beats/min while taking clomipramine.
Ms. Tai said that her study supported the hypothesis that anxiety plays a role in premature ejaculation and that clomipramine's antianxiety effects may be responsible for its efficacy in retarding ejaculation.