Role of the nitric oxide donor linsidomine chlorhydrate (SIN-1) in the diagnosis and treatment of erectile dysfunction

Urology. 1994 Oct;44(4):553-6. doi: 10.1016/s0090-4295(94)80058-8.


Objectives: Recently, nitric oxide was shown to be a mediator of penile erection in men and the nitric oxide donor linsidomine chlorhydrate (SIN-1) was introduced as a novel treatment option in patients with erectile dysfunction. We now present our follow-up results with the intracavernous application of SIN-1.

Methods: One hundred thirteen patients with erectile dysfunction of various etiologies and 10 normal control subjects underwent intracavernous pharmacotesting with 1 mg SIN-1. Of the 113 patients, 71 (62.8%) underwent additional pharmacotesting with a mixture of papaverine (15 mg/mL) and phentolamine (0.5 mg/mL) (P/P). Forty-eight responders to SIN-1 were enrolled in an autoinjection program with this substance.

Results: All normal control subjects had full rigid erections lasting 40 to 70 minutes. Of 113 patients, 78 (69%) had responses sufficient for intercourse with SIN-1, and the other 35 patients (31%) demonstrated inadequate responses. All 44 responders to SIN-1 who also received P/P had erections sufficient for intercourse with P/P in doses of 0.25 to 2 mL (mean, 0.6 +/- 0.3 mL). Six patients (13.6%) had prolonged erections with minimal to moderate doses of P/P. From the total of 27 patients who had erections insufficient for intercourse with SIN-1, 20 (74.1%) had good responses with 0.25 to 2.0 mL P/P (mean, 1.5 +/- 0.5 mL). One patient (4%) had a prolonged erection with 1.0 mL P/P: After 10 to 150 injections/patient (total of 1160 injections; mean, 24.1 injections), no significant side effects were noted with SIN-1.

Conclusions: Our data suggest that intracavernous SIN-1 is safe and efficacious in the majority of patients with erectile dysfunction; however, it has a lower smooth muscle relaxing effect than a combination of P/P. The absence of severe side effects, including priapisms, may be explained by the use of a physiologic pathway for induction of the erectile response and the rapid intracavernous decomposition of SIN-1.

Publication types

  • Clinical Trial
  • Controlled Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Drug Therapy, Combination
  • Electromyography
  • Erectile Dysfunction / drug therapy*
  • Erectile Dysfunction / etiology
  • Erectile Dysfunction / physiopathology
  • Follow-Up Studies
  • Humans
  • Injections
  • Male
  • Middle Aged
  • Molsidomine / analogs & derivatives*
  • Molsidomine / pharmacology
  • Molsidomine / therapeutic use
  • Papaverine / pharmacology
  • Papaverine / therapeutic use
  • Penile Erection / drug effects
  • Phentolamine / pharmacology
  • Phentolamine / therapeutic use
  • Self Administration
  • Vasodilator Agents / pharmacology
  • Vasodilator Agents / therapeutic use*


  • Vasodilator Agents
  • linsidomine
  • Molsidomine
  • Papaverine
  • Phentolamine