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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. In the trials the AUA guideline reviewed, 29.5% to 78.1% of men had successful intercourse, depending on how success was defined. Only men with a positive in-office test proceeded to home treatment in most of those trials. Intraurethral alprostadil is generally less effective than intracavernosal injection but is less invasive.[1]

For pharmacology, see Intraurethral Alprostadil.

Indications​

IndicationPractical role
PDE5i contraindication, failure or intoleranceNeedle-free ED option; the AUA advises informing men with ED of it and performing an in-office test first [1]
Needle aversion or limited willingness for ICILower efficacy than ICI but easier to accept for some patients; EAU 2026 recommends topical or intraurethral alprostadil as an alternative first-line option for well-informed men who prefer less invasive treatment .[6]
Post-prostatectomy ED treatmentMUSE may provide assisted erections when PDE5 inhibitors are contraindicated or oral medication is declined.[1] A separate open-label trial compared nightly MUSE with nightly sildenafil after bilateral nerve-sparing surgery; it did not test spontaneous recovery against no treatment.[7]
Combination with PDE5iA small uncontrolled series described MUSE plus sildenafil in selected men who had not responded to either alone.[8]

Suitable 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 trade-off.

Technique Overview​

MUSE delivers alprostadil through urethral mucosa and not directly into the corpus cavernosum, so the doses are much higher than ICI doses. The US label reports priapism (a rigid erection lasting at least 4 hours) in 2 of 1,511 men (0.13%) in the placebo-controlled trials.[4] Counsel patients to seek urgent medical assessment for a prolonged erection because delay can injure erectile tissue.[1][4] The label contraindicates MUSE with urethral stricture, balanitis, severe hypospadias, severe penile curvature, and acute or chronic urethritis, so check the urethra and glans before prescribing to a reconstructive patient.[4] Alprostadil hypersensitivity, sickle cell disease or trait, thrombocythemia, polycythemia, multiple myeloma, and a medical condition making sexual activity inadvisable are also labeled contraindications.[4] Anticoagulant use or a bleeding disorder calls for an individual bleeding-risk assessment because urethral abrasion can cause spotting; these are cautions, not labeled contraindications.[4]

The AUA guideline lists 100, 250, 500 and 1,000 microgram doses; the last US label (revised May 2024) lists 250, 500 and 1,000 micrograms, recommends 250 micrograms for the first supervised dose and allows no more than two systems in 24 hours.[1][4] MUSE is no longer marketed in the United States. The final DailyMed listing gives marketing end dates of December 31, 2022 (250 micrograms) and April 30, 2023 (500 and 1,000 micrograms), and Drugs@FDA and the Orange Book list all strengths under NDA 020700 as discontinued. Confirm supply before offering an in-office test.[4][5] For any unexpired product supplied under the US label, check storage: unopened pouches are refrigerated at 2–8 °C; they may be kept at 20–25 °C for up to 14 days and should not be exposed above 30 °C.[4] The AUA guideline advises choosing the lowest dose expected to produce an erection sufficient for intercourse for the in-office test, because adverse events increase with dose.[1] EAU 2026 guidance describes a 500-microgram starting strategy for intraurethral alprostadil[6], whereas the US MUSE label recommends 250 micrograms for the first supervised dose.[4] These are different starting strategies; subsequent doses are titrated to the lowest effective dose.[4][6]

Key Steps​

  1. Have the patient urinate and insert MUSE within 10 minutes. Residual urine aids dissolution and dispersal of the pellet.[4]
  2. Wash and dry the hands. Remove the cover without operating the button; avoid touching the stem and tip, and confirm that the pellet is visible in the applicator tip. Gently stretch the penis and compress the glans from top to bottom to straighten the urethra, then insert the applicator to its collar without force. If insertion causes discomfort or pulling, withdraw slightly and reposition.[4]
  3. Depress the button fully and hold for five seconds, then release it and gently move the applicator side to side. Remove the applicator and inspect its tip; if the pellet remains, repeat the labeled insertion and release steps.[4]
  4. Keep the penis upright and roll it between the hands for 30-60 seconds.
  5. Have the patient walk or stand for about 10 minutes to aid blood flow. Onset is expected within 5-10 minutes, and the effect usually lasts 30-60 minutes.
  6. Perform the first dose under medical supervision and monitor for hypotension. Review antihypertensive medicines because concomitant use may increase the risk of hypotension.[4] The US label reports symptomatic hypotension in 3% and syncope in 0.4% during in-clinic dosing; postmarketing syncope has occurred within one hour.[4] Counsel patients to avoid driving or hazardous tasks where hypotension or syncope could cause injury.[4] An optional constriction band was allowed in the comparative ICI trial.[3]
  7. Use a condom with a pregnant partner. Counsel female partners that vaginal burning or itching was reported; whether the medication caused it is uncertain.[4]

Outcomes & Evidence​

Among men with a positive in-office response who reported at least one home administration, 299 of 461 (64.9%) assigned to alprostadil reported intercourse at least once during three months of home treatment, compared with 93 of 500 (18.6%) assigned to placebo.[2] Only men with a positive in-office response (996 of 1,511, 65.9%) were randomized.[2] Mild penile pain followed 10.8% of alprostadil administrations in the published trial.[2] The US label reports penile pain in 32% of MUSE-treated men versus 3% of placebo-treated men during home treatment.[4] The published trial described no priapism or penile fibrosis, while the label reports two priapism cases across the two pivotal studies.[2][4]

In a randomized crossover trial that enrolled 111 men, 68 entered the at-home efficacy analysis. At least one erection sufficient for intercourse occurred in 63 of 68 men (92.6%) using intracavernosal alprostadil alfadex and 42 of 68 (61.8%) using MUSE with an optional constriction band (p < 0.0001).[3] More patients and partners preferred the injection.[3] The AUA guideline advises counseling men that the intraurethral route is generally less effective than ICI.[1]

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)00442-2

4. Meda Pharmaceuticals (Viatris). MUSE (alprostadil) urethral system: US prescribing information. Revised 5/2024. FDA label; DailyMed SPL version 21 (effective May 15, 2024, the last version published) lists the marketing end dates. DailyMed

5. US Food and Drug Administration. Drugs@FDA: MUSE (alprostadil) urethral suppository, NDA 020700 (Viatris), all four strengths listed as discontinued (data updated September 24, 2026); Orange Book data files downloaded September 27, 2026 list the same products as DISCN. Drugs@FDA

6. European Association of Urology. "EAU Guidelines on Sexual and Reproductive Health." Limited Update March 2026; sections 5.6.3.g and 5.6.12. https://uroweb.org/guidelines/sexual-and-reproductive-health/chapter/management-of-erectile-dysfunction

7. McCullough AR, Hellstrom WG, Wang R, Lepor H, Wagner KR, Engel JD. "Recovery of erectile function after nerve sparing radical prostatectomy and penile rehabilitation with nightly intraurethral alprostadil versus sildenafil citrate." J Urol. 2010;183(6):2451–2456. doi:10.1016/j.juro.2010.01.062

8. Nehra A, Blute ML, Barrett DM, Moreland RB. "Rationale for combination therapy of intraurethral prostaglandin E(1) and sildenafil in the salvage of erectile dysfunction patients desiring noninvasive therapy." Int J Impot Res. 2002;14(Suppl 1):S38–S42. doi:10.1038/sj.ijir.3900795