A 35-year-old man with established rheumatic mitral stenosis and a history of acute rheumatic fever presents for long-term prophylaxis to prevent recurrent streptococcal infection and further cardiac damage. He has no penicillin allergy. What is the drug of choice for secondary prophylaxis in this patient?

## Secondary Prophylaxis in Rheumatic Heart Disease **Key Point:** Benzathine penicillin G (BPG) 1.2 million units intramuscularly every 4 weeks is the gold-standard drug of choice for secondary prophylaxis in patients with a history of acute rheumatic fever (ARF) and/or established rheumatic heart disease (RHD). ### Rationale for Benzathine Penicillin G **High-Yield:** BPG is preferred over oral penicillin because: 1. **Superior compliance:** Single IM injection every 4 weeks ensures adherence; oral regimens depend on patient compliance 2. **Sustained therapeutic levels:** Maintains bactericidal penicillin levels for the entire 4-week interval 3. **Proven efficacy:** Reduces recurrence of ARF by >90% when given regularly 4. **Cost-effective:** Especially in resource-limited settings (India, other endemic regions) 5. **No drug interactions:** Unlike oral agents ### Duration of Secondary Prophylaxis | Clinical Scenario | Duration of Prophylaxis | |-------------------|-------------------------| | **ARF without carditis** | 5 years or until age 21 (whichever is longer) | | **ARF with carditis but no permanent cardiac damage** | 10 years or until age 25 (whichever is longer) | | **ARF with carditis AND permanent cardiac damage (RHD)** | Lifelong | | **Established RHD (with or without carditis history)** | Lifelong | **Clinical Pearl:** In this patient with established mitral stenosis (permanent cardiac damage), lifelong prophylaxis is indicated. BPG 1.2 million units IM every 4 weeks is continued indefinitely. ### Dosing Schedule - **Standard dose:** 1.2 million units IM every 4 weeks - **For patients <27 kg:** 600,000 units IM every 4 weeks - **Route:** Intramuscular only (IM); never IV - **Injection site:** Gluteal or deltoid muscle; rotate sites to prevent local reactions ### Comparison with Oral Alternatives | Agent | Dose | Frequency | Compliance | Evidence | Status | |-------|------|-----------|-----------|----------|--------| | **Benzathine PCN G** | 1.2 MU | Every 4 weeks IM | Excellent | Gold standard | **First-line** | | **Penicillin V** | 250 mg | Twice daily PO | Poor | Inferior to BPG | Second-line if IM not feasible | | **Amoxicillin** | 250–500 mg | Twice daily PO | Poor | Not recommended | Not indicated | | **Erythromycin** | 250 mg | Four times daily PO | Poor | For PCN-allergic only | Allergy alternative | | **Cephalexin** | 500 mg | Twice daily PO | Poor | Not recommended | Not indicated | **Warning:** Oral penicillin V (250 mg twice daily) is an acceptable alternative ONLY if IM administration is absolutely contraindicated or refused by the patient. Compliance with oral prophylaxis is significantly lower, increasing the risk of recurrent ARF and progressive cardiac damage. **Mnemonic:** **BPG-4:** **B**enzathine **P**enicillin **G** every **4** weeks — the gold-standard secondary prophylaxis regimen for RHD. [cite:Harrison 21e Ch 297; Park 26e Ch 12]