Evaluation of a no-needle penile injector: a preliminary study evaluating tissue penetration and its hemodynamic consequences in the rat

Objectives

Intracavernous needle injection is an effective delivery method for pharmacotherapy of erectile dysfunction. Needle phobia, pain, and concern about local tissue injury have stimulated the search for new, less invasive means of inducing penile erection. In this preliminary communication, we evaluate a jet injector as an alternative to needle injection for intracavernous delivery of vasoactive drugs.

Methods

Jet injection was evaluated in three groups of rats receiving either India ink, saline, or papaverine into the penis. The ability of the jet injection to penetrate through the tunica albuginea and deliver liquid to the corpora cavernosa smooth muscle was assessed by the degree of staining within the corpus cavernosum (ink group), histologic change (saline group), and rise in intracavernous pressure (papaverine group). Erectile capacity following cavernous nerve electric stimulation was compared before and 1 hour after injection of saline or papaverine.

Results

Ink traversed the skin and tunica albuginea with extensive deposition noted within the cavernous spaces. Varying degrees of subcutaneous hemorrhage were seen with saline jet injection; however, the corpus cavernous smooth muscles showed no evidence of injury. Jet injection of papaverine 3250 gmg significantly increased cavernous pressure (39.4 ± 4.6 cm H₂O) compared with saline injection (2.8 ± 1.3 cm H₂O).

Conclusions

We conclude that acute jet injection is an effective method for intracavernous delivery of drugs. Long-term effects should be evaluated prior to clinical use.