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?
A. Erythromycin 250 mg orally four times daily
B. Cephalexin 500 mg orally twice daily
C. Benzathine penicillin G 1.2 million units intramuscularly every 4 weeks
D. Amoxicillin 500 mg orally twice daily
Explanation
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-YieldNEET PG
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
Table
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
Table
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:Benzathine Penicillin G every 4 weeks — the gold-standard secondary prophylaxis regimen for RHD.
Harrison 21e Ch 297; Park 26e Ch 12
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