What is the role of injectable Bleomycin (Bleomycin sulfate) in the treatment of warts?

Injectable Bleomycin for Warts Treatment

Injectable bleomycin (0.1-1 mg/mL solution) is recommended as a third-line treatment option for recalcitrant warts that have failed conventional therapies, with particularly high efficacy for periungual warts (94%) compared to plantar warts (60-66%). 1

Mechanism and Efficacy

Bleomycin is a cytotoxic antibiotic that works by inhibiting DNA synthesis and damaging dividing basal layer cells when injected intralesionally into warts. Its efficacy has been demonstrated in multiple controlled studies:

• Intralesional bleomycin shows superior clearance rates (94.9% of patients, 97% of warts) compared to cryotherapy (76.5% of patients, 82% of warts) 2
• Complete cure rates of 80% have been reported with minimal recurrence 3
• Efficacy varies by location:
  • Periungual warts: 94% clearance
  • Warts on extremities: 95% clearance
  • Plantar warts: 60-66% clearance 4, 5

Administration Protocol

1. Concentration: 0.1-1 mg/mL solution (0.5 mg/mL appears as effective as 1 mg/mL) 6
2. Technique: Inject directly into the wart after local anesthesia until blanching occurs
3. Dosing: Total cumulative dose should not exceed 2 mg in one session 3
4. Treatment schedule: One to three treatments at 2-3 week intervals 1

Treatment Algorithm

1. First-line therapy: Topical salicylic acid (15-40%) applied daily after paring for 3-4 months
2. Second-line therapy: Cryotherapy applied every 2-4 weeks for at least 3 months
3. Third-line therapy: Injectable bleomycin for recalcitrant warts that have failed conventional treatments

Contraindications and Precautions

While there are no absolute contraindications to bleomycin use, caution should be exercised in patients with:

• Advanced age (>40 years)
• Significant smoking history
• Reduced renal function
• Pre-existing lung disease 7

Side Effects and Complications

1. Common local effects:

   • Pain during and after injection (most common)
   • Hemorrhagic eschar formation
   • Local inflammation

2. Serious but rare complications:

   • Pulmonary toxicity (pneumonitis and fibrosis) - primarily with systemic use
   • Raynaud's phenomenon
   • Skin hyperpigmentation 7

Monitoring

Most warts treated with intralesional bleomycin will develop a hemorrhagic eschar within 24-72 hours, which should be pared away at follow-up visits before any subsequent injections. Treatment can be repeated after 2-3 weeks if there is partial or no response 3.

Advantages and Limitations

Advantages:

• High efficacy for recalcitrant warts (76-97%)
• Minimal scarring when properly administered
• High patient satisfaction rates
• Lower concentrations (0.5 mg/mL) appear equally effective as higher ones (1 mg/mL) 6

Limitations:

• Pain during and after injection
• Requires clinical expertise for administration
• Not first-line therapy due to potential side effects
• Variable response based on wart location

Injectable bleomycin should be reserved for warts that have failed conventional treatments like salicylic acid and cryotherapy, particularly for periungual warts where it shows the highest efficacy 7, 1.