This article is free online until 12/31/2010 (following the linked title), though the abstact tells the story.
Nathan J. Kolla, MD, MA, MSc, Philip E. Klassen, MD, Michael E. Kuban, MSc, Thomas Blak, BA and Ray Blanchard, PhD, Double-blind, Placebo-controlled Trial of Sildenafil in Phallometric Testing, J Am Acad Psychiatry Law 38:4:502-511 (2010).
Not all males undergoing phallometric testing for assessment of deviant sexual interests respond adequately to test stimuli. As poor response may be linked to hormonal, neurologic, vascular, or psychogenic causes, we studied the ability of sildenafil, an effective proerectile agent, to increase penile blood flow during phallometric testing. Twenty-two males completed this double-blind, placebo-controlled trial of sildenafil (100 mg). Each participant underwent phallometric testing with and without sildenafil. On average, each subject’s peak response was 50 percent greater in the sildenafil condition than it was in the placebo condition (p < .05). Correlations between participants' penile response to human stimulus categories, with or without treatment, were all very high (r = 0.77–0.89) and statistically significant, thus indicating excellent reliability between the two test conditions. These results support earlier findings that sildenafil significantly increases phallometric response among middle-aged males. Moreover, pharmacologic treatment did not compromise the reliability of phallometric diagnosis.