Basics

Phenoxymethylpenicillin is a narrow-spectrum antibiotic, also commonly referred to as penicillin V. It is a phenoxymethyl analogue of penicillin G or benzylpenicillin. Phenoxymethylpenicillin is an orally active, naturally occurring penicillin used to treat mild to moderate infections of the respiratory tract, skin, and soft tissues caused by penicillin-susceptible microorganisms. Penicillin V is usually administered as a tablet or solution for parenteral use.

Pharmacology

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.

Toxicity

Possible side effects:

Gastrointestinal symptoms
allergic skin reactions up to allergic shock,
skin and mucous membrane changes (especially in the mouth),
changes in blood count and anemia
fever
oedema
palpitations
bronchial spasms
Joint pain

Toxicological data

LD50 (rat, oral): >1040 mg/kg

Author

Markus Falkenstätter, BSc

Pharmacy student

Markus Falkenstätter is a writer on pharmaceutical topics in Medikamio's medical editorial team. He is in the last semester of his pharmacy studies at the University of Vienna and loves scientific work in the field of natural sciences.

Reviewer

Mag. pharm. Stefanie Brandauer

Pharmacist

Stefanie Lehenauer has been a freelance writer for Medikamio since 2020 and studied pharmacy at the University of Vienna. She works as a pharmacist in Vienna and her passion is herbal medicines and their effects.

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