What is the Difference Between Penicillin G and Penicillin V?

Penicillin G and Penicillin V are both first-generation penicillins used to treat various infections, but they have some differences in their properties and administration:

1. Source: Penicillin G is a natural penicillin produced directly from the fermentation of Penicillium chrysogenum, while Penicillin V is an oral derivative of Penicillin G.
2. Stability: Penicillin V, also known as phenoxymethyl penicillin, is more acid-stable than Penicillin G, allowing it to be administered orally.
3. Bioavailability: Penicillin G degrades more easily by stomach acid and has less than 30% bioavailability, making it a parenterally administered drug. Penicillin V has a bioavailability of around 65%.
4. Administration: Penicillin G can be administered intravenously or intramuscularly, with the usual doses ranging from 300,000 to 4 million units every 6 to 8 hours. Penicillin V is available in tablets of 250 mg and 500 mg and can be administered orally, with doses usually ranging from 250 to 500 mg.
5. Potassium Salt: Penicillin VK is the potassium salt of Penicillin V, which is also available for oral administration.
6. Activity against Gram-negative Bacteria: Penicillin V is less active against gram-negative bacteria than Penicillin G.

Both Penicillin G and V are susceptible to inactivation by beta-lactamase and are used to treat mild-to-severe infections caused by susceptible bacteria, including endocarditis, diphtheria, anthrax, bacterial meningitis, Lyme disease, gonorrhea, syphilis, actinomycosis, botulism, and others. Side effects of both penicillins include nausea, diarrhea, gastrointestinal upset, headache, dizziness, rash, and hypersensitivity reactions.

Comparative Table: Penicillin G vs Penicillin V

Here is a table comparing the differences between Penicillin G and Penicillin V:

In summary, Penicillin G is highly active against infections and is administered parenterally, while Penicillin V is less active and can be administered orally due to its acid stability.