Chloroquine-induced nitric oxide as a potential treatment of erectile dysfunction associated with the metabolic syndrome: the science and the fiction.

Erectile dysfunction is an important cause of decreased quality of life in men. It is estimated that approximately 30 million men in the US and 100 million worldwide may have erectile dysfunction. Data from epidemiological studies indicate a higher prevalence of impotence in obese men. Obesity may be a risk factor for sexual dysfunction in both sexes; data for the metabolic syndrome are very preliminary and need to be confirmed in larger epidemiological studies. The high prevalence of erectile dysfunction in patients with cardiovascular risk factors suggests that abnormalities of the vasodilator system of penile arteries play an important role in the pathophysiology of erectile dysfunction. Nitric oxide released during non-adrenergic, non-cholinergic neurotransmission and from the endothelium is probably the principal neurotransmitter mediating penile erection. It has been shown that chloroquine administration was associated with an increase in nitric oxide synthesis. Chloroquine was also postulated to enhance insulin sensitivity, which suggests potential benefit in treating the metabolic syndrome-related erectile dysfunction.