Bosentan for Digital Pitted Scars in Scleroderma
Bosentan is NOT effective for treating existing digital pitted scars in scleroderma patients—it only prevents new digital ulcer formation and does not heal established lesions. 1
Critical Distinction: Prevention vs. Healing
The evidence is unequivocal that bosentan's benefit is purely preventive:
Bosentan does not heal existing digital ulcers or pitted scars—the RAPIDS-1 and RAPIDS-2 trials showed no significant difference in complete digital ulcer healing rates compared to placebo (p>0.05 for all comparisons). 2
The drug demonstrated a 48% reduction in new digital ulcer formation, but this preventive effect does not extend to healing established lesions. 1
For healing active digital ulcers or pitted scars, intravenous iloprost or epoprostenol remain the evidence-based options, as these prostanoids have demonstrated efficacy in improving healing of active digital ulcers. 2, 1
Evidence-Based Treatment Algorithm for Digital Lesions
For Existing Pitted Scars (Your Question):
First-line for healing: Intravenous prostanoids (iloprost or epoprostenol) are recommended by the European League Against Rheumatism for healing active digital ulcers. 2, 1
Alternative for healing: Calcium channel blockers (nifedipine 30 mg/day) showed comparable efficacy to intravenous iloprost in small RCTs for healing active digital ulcers, though patient numbers were limited. 2
For Prevention of New Ulcers (Different Clinical Scenario):
First-line prevention: Calcium channel blockers (nifedipine 30 mg/day), which reduced both the number of patients with new digital ulcers and total new ulcers by 50% over 6 weeks (NNT 3.3). 2, 1
Second-line prevention: Intravenous prostanoids for severe cases. 1
Third-line prevention: Bosentan (62.5 mg twice daily for 4 weeks, then 125 mg twice daily) should be reserved for patients with diffuse systemic sclerosis and multiple recurrent digital ulcers who have failed first-line therapies. 1
Why Bosentan Doesn't Work for Existing Scars
The mechanism explains the limitation:
Bosentan blocks endothelin receptors to prevent vasoconstriction and new ischemic injury, but this does not reverse established tissue damage or promote healing of scarred tissue. 3
While bosentan may improve hand function (Scleroderma-HAQ scores with effect size 0.4; 95% CI 0.0 to 0.8), this functional improvement occurs through prevention of new ulcers, not healing of existing ones. 2, 1
Common Pitfall to Avoid
Do not prescribe bosentan expecting it to heal existing digital pitted scars—this is a fundamental misunderstanding of the drug's mechanism and evidence base. The RAPIDS trials explicitly showed no benefit for ulcer healing. 2, 1
If your patient has existing pitted scars requiring treatment, you need a healing-focused intervention (prostanoids or calcium channel blockers), not a preventive agent like bosentan. 2, 1