A 55-year-old man with bullous pemphigoid has been on oral prednisolone 40 mg daily for 6 weeks and achieved clinical remission. However, he develops significant steroid-induced hyperglycemia and osteoporosis. Which agent should be added to allow safe tapering of the corticosteroid dose?

Explanation

## Clinical Context: Steroid-Sparing Strategy This patient has achieved remission on systemic corticosteroids but is developing **steroid toxicity** (hyperglycemia, osteoporosis). The goal is now to **reduce the corticosteroid dose** while maintaining disease control by adding a **steroid-sparing agent**. ## Steroid-Sparing Agents in Bullous Pemphigoid | Agent | Mechanism | Onset | Role in BP | Advantages | |-------|-----------|-------|-----------|------------| | **Dapsone** | Inhibits neutrophil function; anti-inflammatory | Days–weeks | **First-line steroid-sparer** | Rapid onset; excellent efficacy; oral; well-tolerated | | Azathioprine | Purine antagonist; immunosuppressant | Weeks–months | Adjunctive | Slower; requires monitoring | | Cyclosporine | Calcineurin inhibitor | Weeks–months | Niche use | Slower; nephrotoxic; expensive | | IVIG | Polyclonal antibody modulation | Days–weeks | Severe/refractory | Very expensive; reserved for severe cases | | Mycophenolate | IMPDH inhibitor | Weeks–months | Emerging | Slower onset than dapsone | ## Why Dapsone is the Best Choice **Key Point:** Dapsone is the **preferred steroid-sparing agent** in bullous pemphigoid because: 1. **Rapid onset**: Clinical benefit within **days to 2–3 weeks** (faster than azathioprine or cyclosporine) 2. **High efficacy**: Allows significant reduction or even discontinuation of corticosteroids in 60–70% of patients 3. **Oral formulation**: Convenient; no IV access required 4. **Mechanism**: Inhibits neutrophil chemotaxis and function, reducing inflammatory infiltrate in the blister 5. **Safety profile**: Well-tolerated in most patients; side effects are manageable with monitoring **High-Yield:** Dapsone is the **gold standard steroid-sparer** in BP — it is superior to azathioprine for speed of action and is preferred over cyclosporine due to lower cost and better tolerability. ## Practical Management **Mnemonic: DAPSONE for Steroid-Sparing in BP** — **D**ose 50–100 mg daily; **A**void in G6PD deficiency; **P**atient monitoring (CBC, LFTs); **S**teroid reduction begins after 2–3 weeks; **O**nset rapid; **N**eutrophil inhibition; **E**xcellent efficacy. **Clinical Pearl:** Before starting dapsone, check: - G6PD status (dapsone causes hemolysis in G6PD-deficient patients) - Baseline CBC and liver function tests - Baseline methemoglobin level (rare but serious side effect) ## Why Other Agents Are Not First-Line Steroid-Sparers **Cyclosporine**: Slower onset (weeks–months); nephrotoxic; expensive; reserved for cases where dapsone is contraindicated or ineffective. **IVIG**: Very expensive; reserved for severe, refractory BP or cases with contraindications to conventional agents. **Methotrexate**: Not established as effective in BP; more commonly used in pemphigus vulgaris.