Effect of nitrazepam on nocturnal penile tumescence and rigidity measurement by RigiScan

Abstract

Objective To investigate whether nitrazepam can increase the accuracy of RigiScan measurement of nocturnal penile tumescence and rigidity （NPTR） by improving the sleep quality of patients. Methods All participants received NPTR measurement for two consecutive nights. In Trial 1， 125 normal volunteers were randomly assigned into the control group （n = 68） and experimental group （n = 57）. They took either a placebo or 10 mg of nitrazepam before NPTR testing on the second night to observe the effect of nitrazepam on nocturnal penile erections in the normal population. In Trial 2， 128 patients with erectile dysfunction were randomly assigned into the control group （n = 64） and experimental group （n = 64）. They took either a placebo or 10 mg of nitrazepam before NPTR testing to observe the effect of nitrazepam on NPTR detection parameters including effective erection times （EEE）， total erection duration （TED）， erection duration with erection rigidity≥60% （D60）， average erection rigidity （AER）， average erection tumescence circumference （AET）， rigidity activity unit （RAU） and tumescence activity unit （TAU） at the tip and base of the penis and the normal erection rates. Results In Trial 1， there were no statistically significant differences in NPTR parameters and normal rates between two groups on the second night （all P > 0.05）. The Richards-Campbell Sleep Questionnaire （RCSQ） score in the experimental group was higher than that in the control group （P < 0.001）. In Trial 2， NPTR parameters （D60tip， D60base， AERbase， RAUtip， TAUtip） on the first night were lower compared to those on the second night in the control group （all P < 0.05）， and there were no significant differences in normal erection rates （67.2% vs. 78.1%， P = 0.065）. Except for AETtip （7.85（6.83，8.98） cm vs. 8.10（7.50，8.90） cm， P = 0.014）， there were no statistically significant differences in NPTR parameters and normal erection rates between two nights in the experimental group （all P > 0.05）. In comparison between two groups， the parameters on the first night （EEE， D60tip， RAUtip and TAUtip）and those on the second night （EEE， D60tip， D60base， TED， RAUtip， RAUbase， TAUtip and TAUbase） in the experimental group were lower than those in the control group （all P < 0.05）. No significant difference was observed in the normal erection rates on the first night between two groups （67.2% vs. 65.6%， P = 0.852）， and the normal erection rate on the second night in the experimental group was lower than that in the control group （78.1% vs. 57.8%， P = 0.014）. In the experimental group， the RCSQ scores on two nights were higher compared to those in the control group， and the RCSQ scores on the first night were lower than those on the second night in both groups （both P < 0.05）. Conclusions NPTR measurement yields the first night effect. Nitrazepam can significantly inhibit the nocturnal penile erection. Improving sleep quality cannot eliminate the first night effect， whereas increase the false negative rate of NPTR measurement. Nitrazepam should be avoided in the NPTR measurement for patients with normal sleep， whereas it can be given for patients with sleep disorders or sleep difficulty after full consideration of the advantages and disadvantages.

Keywords

• erection dysfunction|nitrazepam|nocturnal penile tumescence and rigidity|first night effect|sleep quality