Intraurethral Alprostadil (MUSE)
The Medicated Urethral System for Erection (MUSE) delivers a small alprostadil (prostaglandin E1) pellet into the urethra via a prefilled applicator. The drug is absorbed through the urethral mucosa into the corpus spongiosum and diffuses into the corpora cavernosa, producing smooth muscle relaxation and erection independent of neurogenic stimulation. Efficacy is approximately 40–65%, lower than intracavernosal injection but with less invasiveness.
This atlas page is the administration and counseling companion to the full Intraurethral Alprostadil pharmacology hub.
Indications
| Indication | Practical role |
|---|---|
| PDE5i failure or intolerance | Needle-free second-line ED therapy[1] |
| Needle aversion or limited willingness for ICI | Lower efficacy than ICI but easier to accept for some patients |
| Post-prostatectomy ED rehabilitation | Alternative when PDE5i are contraindicated or poorly tolerated |
| Salvage with PDE5i | Can be combined with oral PDE5i in selected non-responders |
Best candidates are motivated patients who can manipulate the applicator, understand the lower efficacy compared with ICI, and value avoiding a needle enough to accept that tradeoff.
Technique Overview
MUSE delivers alprostadil through urethral mucosa rather than directly into the corpus cavernosum. That is why doses are much higher than ICI doses but priapism and fibrosis risk are lower.
The practical dose range is 125-1000 micrograms. Many protocols start at 500 micrograms during supervised in-office titration because very low starting doses can create an early false impression of failure.
Key Steps
- Have the patient urinate immediately before administration; residual urine lubricates the urethra and helps dissolve / disperse the pellet.
- Insert the applicator fully into the meatus and urethra.
- Depress the button to release the pellet.
- Remove the applicator and roll the penis between the hands for 30-60 seconds.
- Wait 5-10 minutes for onset; effect usually lasts 30-60 minutes.
- Consider a constriction band in selected patients, especially spinal-cord-injury patients prone to hypotension.
- Use a condom with a pregnant partner and counsel female partners about possible vaginal burning from drug transfer.
Outcomes & Evidence
The pivotal randomized trial found successful intercourse in 64.9% of alprostadil users versus 18.6% with placebo during the home phase.[2] Real-world continuation is lower, driven by insufficient rigidity, urethral / penile pain, cost, and technique frustration.
The central comparison is MUSE versus ICI. ICI produces firmer, more reliable erections, but MUSE is needle-free and had no priapism or fibrosis signal in the pivotal trial. Head-to-head data favor ICI for efficacy but show that some patients prefer MUSE because it is easier to administer and less invasive.[3]
Do not oversell MUSE. It is a useful second-line option for the right patient, not a replacement for ICI or penile implant in severe vasculogenic or neurogenic ED.
References
1. Burnett AL, Nehra A, Breau RH, et al. "Erectile dysfunction: AUA guideline." J Urol. 2018;200(3):633-641. doi:10.1016/j.juro.2018.05.004
2. Padma-Nathan H, Hellstrom WJ, Kaiser FE, et al. "Treatment of men with erectile dysfunction with transurethral alprostadil." N Engl J Med. 1997;336(1):1-7. doi:10.1056/NEJM199701023360101
3. Shabsigh R, Padma-Nathan H, Gittleman M, et al. "Intracavernous alprostadil alfadex is more efficacious, better tolerated, and preferred over intraurethral alprostadil plus optional ACTIS: a comparative, randomized, crossover, multicenter study." Urology. 2000;55(1):109-113. doi:10.1016/s0090-4295(99)00420-9