What is the recommended dosing regimen for Xiaflex (collagenase clostridium histolyticum)?

Xiaflex Dosing Regimen for Peyronie's Disease

For Peyronie's disease, Xiaflex (collagenase clostridium histolyticum) is administered as 0.58 mg per intralesional injection directly into the palpable plaque, with a maximum of 4 treatment cycles (8 total injections) over 24 weeks, with each cycle consisting of 2 injections spaced 1-3 days apart and cycles separated by approximately 6 weeks. 1, 2

Patient Selection Criteria

Before initiating treatment, confirm the patient meets all FDA-approved criteria:

• Penile curvature between 30° and 90° with a palpable plaque confirmed on physical examination 3, 1, 2
• Intact erectile function (with or without pharmacotherapy) 3, 1
• Stable disease phase without active pain or progressive deformity for at least 3 months 4, 2
• Age ≥18 years 1
• Treatment must be administered by a urologist experienced in urological disease management 1, 4

Detailed Treatment Protocol

Injection Technique

• Administer 0.58 mg per injection directly into the Peyronie's plaque 1, 2
• Each treatment cycle consists of 2 injections spaced 1-3 days apart 1
• Maximum of 4 treatment cycles (8 total injections) 1
• 6-week intervals between treatment cycles 1, 4
• Total treatment duration spans 24 weeks maximum 2

Modeling Component

• Clinician-administered modeling should be performed 24-72 hours after the second injection of each cycle 1
• Patient-performed penile modeling exercises should be done daily between treatment cycles 1
• This combination of intralesional injection with modeling is specifically recommended by the AUA guidelines (Evidence Strength Grade B) 3, 1

Stopping Rules

Discontinue treatment if:

• Curvature decreases to <15° after any treatment cycle - do not administer subsequent cycles 1
• The safety of more than one complete treatment course (4 cycles) has not been established 1

Expected Outcomes

• Mean curvature reduction of 17° compared to 9.3° with placebo at one-year follow-up 1
• 44.4% of patients achieve 0-5° of normal contracture in clinical trials 5
• Improvements in sexual function and quality of life are documented outcomes 1

Safety Monitoring and Adverse Events

Counsel patients about common and serious adverse events:

• Most common: Penile ecchymosis, swelling, and pain (typically mild to moderate and self-resolving) 1, 4
• Rare but serious: Corporal rupture (requires immediate evaluation) 1, 4
• Most adverse events resolve without intervention 1

Critical Pitfalls to Avoid

• Do not use Xiaflex for curvature <30° or >90° - outside FDA-approved range 1, 2
• Do not proceed without confirming intact erectile function - this is an absolute requirement 3, 1, 4
• Do not treat during active disease phase with ongoing pain or progressive deformity 4, 2
• Do not expect complete resolution - average improvement is modest at 17°, and residual curvature may require additional interventions 1, 4
• Do not use for pain management - Xiaflex is not indicated for pain control in Peyronie's disease 2

Alternative Considerations

If Xiaflex fails or is contraindicated, the treatment algorithm proceeds to:

• Penile traction therapy for patients preferring non-invasive options 4, 2
• Surgical intervention only after disease stability for 3-6 months and conservative therapy failure for approximately 1 year 4, 2
• Tunical plication for curvature <60° with preserved erectile function 4
• Penile prosthesis for concurrent erectile dysfunction 4, 2