A 48-year-old man with pemphigus vulgaris has achieved disease remission on prednisolone 40 mg/day after 8 weeks of therapy. Which agent should be added now to facilitate corticosteroid tapering and prevent relapse?

Explanation

## Steroid-Sparing Strategy in Pemphigus Vulgaris **Key Point:** Once disease remission is achieved with systemic corticosteroids, a steroid-sparing immunosuppressive agent must be added to permit safe tapering and reduce long-term corticosteroid toxicity. ### Rationale for Steroid-Sparing Therapy Prolonged high-dose corticosteroids carry significant morbidity: osteoporosis, infections, metabolic syndrome, and iatrogenic Cushing syndrome. Steroid-sparing agents allow gradual dose reduction while maintaining disease control. ### First-Line Steroid-Sparing Agents | Agent | Onset | Mechanism | Monitoring | Preference | |-------|-------|-----------|-----------|------------| | **Azathioprine** | 6–8 weeks | Purine antagonist; inhibits T & B cells | TPMT, CBC, LFTs | First-line | | **Mycophenolate mofetil** | 4–6 weeks | Inosine monophosphate dehydrogenase inhibitor | CBC, LFTs | Alternative; better tolerated | | Rituximab | 2–4 weeks | Anti-CD20 monoclonal antibody | CD19+ counts, immunoglobulins | Refractory disease | | Dapsone | 24–48 hours | Oxidative burst inhibition | G6PD, methemoglobin | Mucocutaneous only | **High-Yield:** Azathioprine is the most widely used and cost-effective steroid-sparer in India and remains first-line in most guidelines. TPMT (thiopurine methyltransferase) testing is essential before initiation to avoid toxicity in deficient patients. ### Typical Steroid-Tapering Protocol 1. Add azathioprine 1–2 mg/kg/day (usually 50–100 mg/day) once remission is achieved 2. Allow 6–8 weeks for azathioprine to reach therapeutic effect 3. Begin prednisolone taper: reduce by 5–10 mg every 1–2 weeks 4. Target maintenance prednisolone: 5–10 mg/day or alternate-day dosing 5. Continue azathioprine for 2–3 years, then consider withdrawal if sustained remission **Clinical Pearl:** Dapsone has rapid onset but is reserved for mucocutaneous-predominant disease or as adjunctive therapy; it is not suitable as a primary steroid-sparer in generalized pemphigus vulgaris. **Warning:** Initiating steroid tapering without concurrent steroid-sparing therapy risks relapse and disease flare.