Is Penicillin V (PVK) the oral form of benzylpenicillin (Penicillin G)?

Penicillin V (PVK) is the Oral Form of Benzylpenicillin (Penicillin G)

Yes, Penicillin V (phenoxymethylpenicillin or PVK) is the oral form of benzylpenicillin (Penicillin G), specifically designed to be more resistant to gastric acid degradation. 1

Differences Between Penicillin V and Penicillin G

Penicillin V and Penicillin G share the same basic beta-lactam ring structure but have important differences:

• Chemical Structure: Penicillin V (phenoxymethylpenicillin) differs from Penicillin G (benzylpenicillin) by having a phenoxymethyl side chain instead of the phenyl acetic acid side chain found in Penicillin G 2

• Route of Administration:

  • Penicillin V: Administered orally as tablets or suspension 3
  • Penicillin G: Primarily administered parenterally (injection) 4

• Acid Stability: Penicillin V is specifically preferred for oral administration because it is more resistant to gastric acid degradation than Penicillin G 1

Clinical Applications

The American Heart Association guidelines clearly state that both forms are used for treating Group A Streptococcal (GAS) infections, but with different routes of administration:

• Oral Therapy: Penicillin V is the oral antibiotic of choice, typically dosed at 250-500 mg 2-3 times daily for adults and adolescents for a full 10-day course 1

• Parenteral Therapy: Benzathine Penicillin G is given as an intramuscular injection when:

  • Patient compliance with oral therapy is questionable
  • Patient has personal/family history of rheumatic fever
  • Patient has environmental risk factors for rheumatic fever 1

Efficacy Considerations

While both forms are effective against susceptible organisms, there are some important clinical considerations:

• Both medications have shown similar clinical outcomes when used appropriately for their intended routes of administration 5

• Some studies have raised questions about the microbiological efficacy of both oral Penicillin V and intramuscular Benzathine Penicillin G in eradicating group A streptococci, with failure rates of approximately 35-37% 6

• Despite these concerns, penicillin remains the first-line treatment for GAS pharyngitis due to its narrow spectrum, proven efficacy, low cost, and the fact that GAS has never developed resistance to penicillin 1

Alternative Options for Penicillin-Allergic Patients

For patients with penicillin allergy, alternative treatments include:

• Cephalosporins: For non-anaphylactic reactions (note that up to 10% of penicillin-allergic patients may also be allergic to cephalosporins) 1, 7

• Clindamycin: Effective with low resistance rates (approximately 1%) 1, 7

• Macrolides: Such as clarithromycin or azithromycin 7

Key Takeaways

1. Penicillin V is the oral equivalent of Penicillin G, modified to withstand gastric acid
2. Both contain the same beta-lactam ring but have different side chains
3. The choice between them is primarily based on the required route of administration and patient factors
4. Both remain first-line agents for susceptible infections, particularly GAS pharyngitis