Topical and Intraurethral Agents
Topical agents to treat erectile dysfunction are applied to the penis or perineal regions and have included hormone-derived medications, as well as vasodilators. The application of intraurethral prostaglandin E1 (alprostadil) can be done by a urologist or self-administered to the distal male urethra via a drug delivery system. Intraurethral preparations cause cavernosal vasodilation to initiate erection.
Discussion
There are no RCT studies in this area. Topical agents that cause vasodilation, such as minoxidil, PGE1, papaverine, and nitroglycerine, are generally safe however only effective in a minority of patients. They provide an erection sufficient for vaginal penetration in only 22-29% of participants, most likely due to inadequate absorption through the tunica albuginia (Sønksen & Biering-Sørensen 1992). Although showing a significant increase in mean cavernous artery diameter and peak systolic flow velocity with topical application of PGE1, a clinically useful erection was only seen in 2 out of 9 participants (Kim & McVary 1995). One study found topical minoxidil spray to be significantly less effective than comparative treatments with papaverine ICI or a vacuum constriction device. Use of topical agents to treat ED seem to have little if any role to play in the SCI population, particularly in view of the efficacy and reliability of PDE5i and ICI.
Bodner et al. (1999) found in 15 participants that the use of intraurethral alprostadil (PGE1) was ineffective in sustaining an adequate erection, and without a penile ring to sustain any increase in penile circumference (tumescence), patients experienced hypotension from the medication. Based on the evidence to date, there is no need to further explore this area of research.
Conclusion
There is level 2 evidence (from 1 non-randomized controlled trial; Kim et al. 1995) that shows that the use of topical agents is not effective or reliable as a treatment for erectile dysfunction in men with SCI.
There is level 4 evidence (Bodner et al. 1999) which suggests that the use of intraurethral preparations is not effective as treatment for erectile dysfunction in men with SCI.
