Pharmacodynamics
Phenoxymethylpenicillin acts against penicillin-sensitive microorganisms with bactericidal activity. It attacks bacteria during their active multiplication phase by interfering with bacterial cell wall peptidoglycan synthesis. Phenoxymethylpenicillin acts bacteriostatically by binding to specific penicillin-binding proteins (PBPs) located within the bacterial cell wall, which are critical for cell wall synthesis and maintenance, as well as cell division. This disrupts the third and final stage of bacterial cell wall synthesis. This subsequently leads to cell lysis and destruction of the pathogens.
Penicillin V is effective against the following organisms:
- Staphylococci (except penicillinase-producing strains),
- streptococci (groups A, C, G, H, L and M)
- Pneumococci
- Corynebacterium diphtheriae
- Bacillus anthracis
- Clostridia
- Actinomyces bovis
- Streptobacillus moniliformis
- Listeria monocytogenes
- Leptospira
- Neisseria gonorrhoeae
- Treponema pallidum
Pharmacokinetics
When administered orally, phenoxymethylpenicillin is rapidly but incompletely absorbed. The bioavailability of phenoxymethylpenicillin ranges from 25 to 60%. Approximately 50-80% of the given dose is bound to plasma proteins. About 35-70% of an oral dose is metabolized to penicilloic acid, an inactive metabolite. While the drug is rapidly excreted, only 25% of the total dose is detected in the urine. When administered orally, the half-life is approximately 30 minutes. In patients with renal insufficiency, it can last up to 4 hours.