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Intraurethral Alprostadil

MUSE is an alprostadil urethral suppository approved in the United States for erectile dysfunction (ED). It offers a needle-free option, usually with lower efficacy than intracavernosal treatment. Treatment choice should reflect effectiveness, adverse effects, access and patient preference; prior failure of every oral option is not a universal prerequisite. The AUA recommends discussing intraurethral therapy and performing an in-office test, and the EAU permits it as an alternative initial option for appropriately informed patients.[1][2][3]

For related treatments, see Intracavernosal injection agents, PDE5 inhibitors, and Testosterone replacement. MUSE pellets, topical alprostadil cream and injectable alprostadil are different formulations; their instructions and evidence are not interchangeable.

Mechanism and formulation​

Alprostadil is prostaglandin E1. It relaxes cavernosal smooth muscle and promotes arterial inflow and corporal veno-occlusion. Drug absorbed from the urethral mucosa reaches the erectile bodies through communicating vessels. The MUSE pellet contains alprostadil in polyethylene glycol 1450 and is delivered through a single-use urethral applicator.[1]

The current US label lists 250, 500 and 1000 microgram systems. A 125-microgram dose appears in the historical trials and some non-US guidance; it should not be presented as a current US marketed strength. A label establishes the approved presentation, not real-time pharmacy stock.[1][3]

US dosing and administration​

DecisionCurrent US label
Initial dose250 micrograms under medical supervision
TitrationAdjust stepwise on separate occasions to the lowest dose sufficient for intercourse; monitor symptoms of hypotension and demonstrate correct technique
Maximum frequencyTwo single-dose systems in 24 hours; the US label does not specify an additional seven-dose weekly ceiling
Expected responseUsually begins within 5–10 minutes and lasts approximately 30–60 minutes, with individual variation
StorageUnopened pouches refrigerated at 2–8°C; room temperature 20–25°C for up to 14 days before use; do not expose above 30°C

These are product-specific instructions.[1] EAU guidance describes a 500-microgram starting strategy, supported partly by an older open randomized trial; that is different from the US label's starting dose. In Ekman's trial, 166 men were randomized and 142 were included in efficacy analysis; a 500-microgram start improved early response but produced more penile pain during the first four weeks. It does not justify replacing supervised individual titration with an automatic higher dose.[3][4]

Administration checklist​

The current US Instructions for Use provide the complete illustrated technique. Key steps are:[1]

  1. Urinate immediately beforehand; insert within 10 minutes of urination. Wash and dry hands.
  2. Open the pouch, remove the protective cover without operating the button, and verify that the pellet is present. Avoid touching the stem and tip.
  3. Gently stretch the penis to its full length and straighten the urethra. Insert to the applicator collar without force; withdraw slightly and reposition if there is discomfort or pulling.
  4. Depress the button fully and hold for five seconds, then release and gently move the applicator side to side to detach the pellet.
  5. Withdraw while keeping the penis upright and inspect the tip. If the pellet remains, follow the label's reinsertion steps.
  6. With the penis upright and stretched, roll it between the hands for at least 10 seconds. Replace the cover and discard the single-use applicator.

Do not substitute older or another country's instructions for the supplied product leaflet. Check comfort, dexterity and vision during teaching, particularly after reconstruction or with altered sensation.

What efficacy estimates actually mean​

Pivotal placebo-controlled trial​

Padma-Nathan and colleagues enrolled 1,511 men. Of these, 996 (65.9%) achieved an intercourse-sufficient erection during clinic titration. Men responding in clinic entered the randomized home phase; among those reporting at least one home treatment, 299/461 (64.9%) receiving alprostadil versus 93/500 (18.6%) receiving placebo reported successful intercourse at least once over three months.[5]

The 64.9% home result describes selected clinic responders with reported home use, not all men starting MUSE. Likewise, the report that about seven in ten administrations led to intercourse applies to men responsive to treatment; it is not an all-patient success probability.[5]

Comparison with injections and continuation​

In a randomized crossover study of 111 men, intracavernosal alprostadil produced intercourse-sufficient erections after 82.5% of administrations, compared with 53.0% for MUSE with optional constriction support. Patients and partners more often preferred injections. A separate randomized study of 60 men also favored injections for efficacy, but favored MUSE for comfort and continuation.[6][7]

These differing experiences argue against promising that a needle-free route will always be more comfortable or acceptable. Response in a supervised office trial, home usability, partner experience and follow-up are more useful than an isolated efficacy percentage. Long-term discontinuation remains common.[3][6][7]

Safety and contraindications​

Rare priapism is still an emergency

The US label reports two cases of priapism among 1,511 patients (0.13%). Although the original publication abstract reported none, the current label must not be replaced with a claim of zero risk. A rigid erection lasting four hours or longer requires urgent medical assessment. See Priapism management.[1][5]

RiskPractical implication
Penile/urethral pain and spottingCommon local adverse effects. In the US label's home-treatment table, penile pain occurred in 32%, urethral burning in 12%, and minor bleeding/spotting in 5% of active-treatment patients
Hypotension and syncopeDuring clinic titration, symptomatic hypotension occurred in about 3% and syncope in 0.4%; supervise titration and prescribe the lowest effective dose
AntihypertensivesAdditive hypotension is possible; review baseline pressure, orthostasis and other vasoactive drugs
Anticoagulation or bleeding disorderUrethral abrasion may cause more bleeding. Assess risk individually; this is not an instruction to stop prescribed anticoagulants automatically
Partner burning/itchingReported in 5.8% with active treatment versus 0.8% with placebo; the label states that medication versus resumption of intercourse as the cause is uncertain

Rates above come from the product label and reflect its trial populations and observation periods.[1] Avoid driving or hazardous activities when dizziness or fainting could cause injury; postmarketing syncope has occurred within an hour of use.

The US contraindications include:[1]

  • Alprostadil hypersensitivity.
  • Urethral stricture, balanitis, severe hypospadias/curvature, or acute or chronic urethritis.
  • Conditions predisposing to priapism or venous thrombosis/hyperviscosity, including sickle cell anemia or trait, thrombocythemia, polycythemia and multiple myeloma.
  • A medical condition making sexual activity inadvisable.
  • Intercourse with a pregnant partner unless a condom barrier is used.

Use in patients with penile implants has not been studied; this is different from a labeled absolute contraindication. Prior reconstruction and spinal cord injury also require individualized anatomical and safety assessment rather than being automatically classified as label contraindications.[1]

MUSE provides no contraception or protection against sexually transmitted infections. The label recommends adequate contraception when the partner can become pregnant and specifically requires a condom barrier with a pregnant partner. Do not promise that condoms eliminate every partner symptom.[1]

Special populations and combinations​

Spinal cord injury and constriction support​

The frequently cited Bodner report involved 15 men with spinal cord injury, all previously successful with injections. After hypotension in the first three men, the remaining participants used a constriction ring. Erections remained less rigid than with injections, and the three men trying home MUSE discontinued it. This small uncontrolled experience supports caution and supervised testing; it does not establish a universally safe or effective ring-plus-MUSE protocol for spinal cord injury.[8]

If a specialist selects constriction support, teach safe removal and skin monitoring, particularly when sensation is reduced. EAU guidance for constriction rings advises removal within 30 minutes to avoid ischemic injury. A ring is not a guarantee against systemic hypotension.[3]

After radical prostatectomy​

MUSE can provide an assisted erection after prostatectomy when anatomy and safety permit. That differs from proving recovery of spontaneous erectile function. In McCullough's open randomized comparison, 139 men started nightly intraurethral alprostadil and 73 started nightly sildenafil; 97 and 59 completed treatment, respectively. No final endpoint differed significantly between groups. Attrition, lack of an untreated control and assessment involving sildenafil after washout limit claims of equivalent rehabilitation efficacy or prevention of irreversible fibrosis.[9]

Combination therapy and topical cream​

Selected refractory patients may receive specialist-directed combinations, but do not automatically extrapolate between routes. The Garrido-Abad study often cited for adding alprostadil to a PDE5 inhibitor used topical cream, with 170 patients assigned by preference, not randomized MUSE pellets. It cannot establish a standard MUSE-plus-PDE5 regimen.[10]

EAU guidance describes topical alprostadil availability in some European countries. Confirm local approval, supply and instructions; topical cream is not an interchangeable substitute for a US urethral suppository or intracavernosal preparation.[3]

Practical follow-up​

Reassess actual intercourse success, discomfort, dizziness, technique and partner experience. Adjust the dose with the prescriber, or discuss another treatment if the benefit does not justify the burden. Never increase frequency or combine vasoactive preparations simply because an office dose was inadequate. Route-specific dosing and the emergency plan should accompany every prescription.[1][2]

References​

  1. Meda Pharmaceuticals/Viatris. MUSE (alprostadil) US prescribing information, Patient Information and Instructions for Use, revised May 2024; current DailyMed record accessed September 12, 2026. DailyMed.
  2. Burnett AL, Nehra A, Breau RH, et al. Erectile Dysfunction: AUA Guideline. J Urol. 2018;200:633–641. doi:10.1016/j.juro.2018.05.004.
  3. European Association of Urology. Sexual and Reproductive Health Guidelines: Management of Erectile Dysfunction. 2026. EAU.
  4. Ekman P, Sjögren L, Englund G, Persson BE. Optimizing the therapeutic approach of transurethral alprostadil. BJU Int. 2000. doi:10.1046/j.1464-410x.2000.00723.x.
  5. Padma-Nathan H, Hellstrom WJ, Kaiser FE, et al. Treatment of men with erectile dysfunction with transurethral alprostadil. N Engl J Med. 1997;336:1–7. doi:10.1056/NEJM199701023360101.
  6. 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. doi:10.1016/S0090-4295(99)00442-2.
  7. Shokeir AA, Alserafi MA, Mutabagani H. Intracavernosal versus intraurethral alprostadil: a prospective randomized study. BJU Int. 1999. doi:10.1046/j.1464-410x.1999.00021.x.
  8. Bodner DR, Haas CA, Krueger B, Seftel AD. Intraurethral alprostadil for treatment of erectile dysfunction in patients with spinal cord injury. Urology. 1999. doi:10.1016/S0090-4295(98)00435-X.
  9. McCullough AR, Hellstrom WG, Wang R, et al. Recovery of erectile function after nerve sparing radical prostatectomy and penile rehabilitation with nightly intraurethral alprostadil versus sildenafil citrate. J Urol. 2010. doi:10.1016/j.juro.2010.01.062.
  10. Garrido-Abad P, Senra-Bravo I, Manfredi C, et al. Combination therapy with topical alprostadil and phosphodiesterase-5 inhibitors after failure of oral therapy in patients with erectile dysfunction: a prospective, two-arm, open-label, non-randomized study. Int J Impot Res. 2022. doi:10.1038/s41443-020-00400-9.