What is the recommended dosage and administration of intraurethral alprostadil (prostaglandin E1) for erectile dysfunction?

Intraurethral Alprostadil Dosage and Administration for Erectile Dysfunction

For men with erectile dysfunction who are considering intraurethral alprostadil, an in-office test dose and titration must be performed before prescribing, with a recommended initial dose of 500 μg due to its superior efficacy-to-side effect ratio compared to lower doses. 1, 2

Patient Selection and Positioning in Treatment Algorithm

Intraurethral alprostadil is positioned as a second-line therapy for erectile dysfunction after PDE5 inhibitors, particularly appropriate for:

• Men for whom PDE5 inhibitors are contraindicated
• Patients who have failed an adequate trial of PDE5 inhibitors
• Men or partners who prefer to avoid oral medication
• Patients who prefer not to use needles required for intracavernosal injections 3, 1

Dosage Protocol

• Starting dose: 500 μg is recommended as it has higher efficacy than 250 μg with minimal differences in adverse events 2
• Available doses: 250 μg, 500 μg, and 1000 μg
• Dose titration: Titration to the maximum tolerated dose is recommended as it increases efficacy and satisfaction 4
• Administration frequency: Should not be used more than once in a 24-hour period 3

Administration Requirements

1. Mandatory in-office test: The American Urological Association guidelines specify that an in-office test must be performed before prescribing 3
2. Patient instruction: Proper technique must be demonstrated and practiced under healthcare provider supervision 3, 1
3. Initial dose titration: Must be performed in the office to determine the effective dose 3
4. Detailed counseling: Patients must be informed about possible adverse events 3

Administration Technique

The medication is delivered using the Medicated System for Erection (MUSE) - a single-use applicator containing alprostadil suspended in polyethylene glycol 2. The pellet is inserted into the urethra using the applicator.

Efficacy

• The largest clinical study reported 64.9% of men achieving at least one episode of intercourse at home 3
• Successful intercourse rates range from 29.5% to 78.1% across studies 3, 1
• In patients who previously failed intracavernosal injection therapy, 58% achieved sufficient erection in clinic, and 47% of these reported successful intercourse at home 5

Safety Profile and Adverse Events

• Most common side effect is penile pain, occurring in approximately 7.8% of administrations 5
• Hypotension occurs in approximately 3% of patients after the first dose, which is why in-office testing is required 1
• No occurrences of priapism or fibrosis (as seen with intracavernosal injection) 2

Special Considerations

• Combination with sildenafil or a penile constriction device may increase efficacy when single treatments have failed 3, 1
• Can be used in patients with penile prosthesis failure or those experiencing decreased glans engorgement with a functioning prosthesis 6
• Intraurethral alprostadil has shown high patient preference and acceptance rates compared to intracavernosal injection due to its ease of administration 2

Common Pitfalls to Avoid

• Skipping the in-office test dose: This is essential to assess efficacy and monitor for potential adverse effects, particularly syncope
• Inadequate patient instruction: Proper technique is crucial for efficacy
• Exceeding recommended frequency: Should not be used more than once in 24 hours
• Failure to titrate dose: Optimal results often require dose adjustment to the maximum tolerated level