What is the recommended dosage and treatment duration of Penicillin G (Pen G) for bacterial infections?

From the Guidelines

Penicillin G dosage for bacterial infections should be 24 million U/24 h IV either continuously or in 4–6 equally divided doses for 4-6 weeks, as recommended for endocarditis treatment. This dosage is based on the most recent and highest quality study available, which prioritizes morbidity, mortality, and quality of life as the outcome 1. The treatment duration and dosage may vary depending on the type of infection, patient age, and severity, as well as renal function.

• For penicillin-susceptible strains, the recommended dosage is 24 million U/24 h IV either continuously or in 4–6 equally divided doses for 6 weeks 1.
• For penicillin-resistant strains, the recommended dosage is also 24 million U/24 h IV either continuously or in 4–6 equally divided doses for 6 weeks, with the addition of gentamicin for at least the first 2 weeks 1.
• Dosage adjustments are necessary for patients with renal impairment, and clinicians should confirm the infection is caused by penicillin-susceptible organisms before starting treatment.
• Penicillin G works by inhibiting bacterial cell wall synthesis, causing cell death in actively dividing bacteria, and patients should complete the full course of treatment even if symptoms improve to prevent recurrence and antimicrobial resistance.
• Common side effects include allergic reactions, gastrointestinal disturbances, and potential for seizures at very high doses. It is essential to note that the treatment of patients with bacterial infections, especially endocarditis, should be coordinated in consultation with an infectious diseases specialist, as the treatment regimen may need to be tailored to the individual patient's needs and the specific causative organism 1.

From the FDA Drug Label

DOSAGE AND ADMINISTRATION Penicillin G Potassium for Injection, USP may be given intravenously or intramuscularly. The usual dose recommendations are as follows: Adult Patients (*)Because of its short half-life, Penicillin G is administered in divided doses, usually every 4-6 hours with the exception of meningococcal meningitis/septicemia, i.e., every 2 hours. Clinical Indication Dosage Serious infections due to susceptible strains of streptococci (including S. pneumoniae) -septicemia, empyema, pneumonia, pericarditis, endocarditis and meningitis 12 to 24 million units/day depending on the infection and its severity administered in equally divided doses every 4 to 6 hours Serious infections due to susceptible strains of staphylococci-septicemia, empyema, pneumonia, pericarditis, endocarditis and meningitis 5 to 24 million units/day depending on the infection and its severity administered in equally divided doses every 4 to 6 hours.

The recommended dosage and treatment duration of Penicillin G (Pen G) for bacterial infections are as follows:

• Serious infections due to susceptible strains of streptococci: 12 to 24 million units/day, administered in equally divided doses every 4 to 6 hours.
• Serious infections due to susceptible strains of staphylococci: 5 to 24 million units/day, administered in equally divided doses every 4 to 6 hours.
• Treatment duration varies depending on the type and severity of the infection, ranging from 10 to 14 days for syphilis to 4 to 6 weeks for endocarditis. 2

From the Research

Recommended Dosage and Treatment Duration of Penicillin G

The recommended dosage and treatment duration of Penicillin G (Pen G) for bacterial infections vary depending on the type of infection and the causative organism.

• For infective endocarditis caused by streptococci and penicillin-susceptible staphylococci, a dosage of 3 g every 6 hours (q6h) is suitable 3.
• The treatment duration for streptococcal pharyngitis is typically 10 days, with penicillin and amoxicillin being first-line antibiotics 4.
• For infective endocarditis due to penicillin-resistant viridans group streptococci, treatment regimens may include a combination of penicillin and an aminoglycoside, or monotherapy with vancomycin or ceftriaxone, with treatment durations ranging from 2.3 to 5.1 weeks 5.

Factors Influencing Treatment

Several factors can influence the treatment of bacterial infections with Penicillin G, including:

• The type of causative organism and its susceptibility to penicillin 3, 5.
• The patient's age, weight, and renal function, which can affect the plasma concentration of penicillin 3.
• The presence of penicillin-resistant organisms, which may require alternative treatment regimens 6, 5.

Additional Considerations

When treating bacterial infections with Penicillin G, it is essential to consider the potential for resistance and the need for therapeutic drug monitoring, especially in cases where the infection is caused by enterococci 3. Additionally, the development of new penicillins with improved antimicrobial activity and resistance profiles is an ongoing area of research 7, 6.