Source: Υπουργείο Υγείας (CY) Revision Year: 2019 Publisher: Remedica Ltd, Aharnon Str., Limassol Industrial Estate, 3506 Limassol, Cyprus
Pharmacotherapeutic Group: Antibacterials for systemic use, Beta-lactam antibacterials, penicillins
ATC Code: J01CE02
Phenoxymethylpenicillin is a beta-lactam antibiotic which acts by inhibiting bacterial cell wall synthesis. The effect is bactericidal. Available knowledge of pharmacokinetics and pharmacodynamics shows that the effect of the beta-lactam antibiotics depends on the time that the free antibiotic serum concentration is above the minimum inhibitory concentration for the particular bacterium (T>MIC). Based on this knowledge a shorter dosing interval may be considered for maximum clinical effectiveness.
Antibacterial spectrum:
| Sensitive | Streptococci and pneumococci Corynebacterium diphtheriae Pasteurella multocida Peptococci Peptostreptococci Actinomycetes Fusobacteria Capnocytophaga canimorsus Borrelia burgdorferi Borrelia Vincenti |
| Intermediate | Haemophilus influenzae |
| Resistant | Staphylococci Enterococci Moraxella catarrhalis Gram-negative intestinal bacteria Pseudomonas Legionella Bacteroides fragilis Clostridium difficile Mycoplasma Chlamydia |
Resistance occurs (1-10%) in pneumococci. Resistance is common (>10%) in Haemophilus influenzae.
Non beta-lactamase producing Haemophilus influenzae is therapeutically accessible with phenoxymethylpenicillin at a high dose.
Resistance mechanisms: Resistance can arise from the bacterial synthesis of a large number of beta-lactamases that hydrolyse penicillin. Several of these can be inhibited with clavulanic acid.
Additionally, resistance may occur due to the production of altered penicillin-binding proteins (PBP). Resistance is often plasmid-mediated.
Cross-resistance occurs within the group of beta-lactam antibiotics (penicillins and cephalosporins).
Resistance development: Penicillin-resistant pneumococci are resistant to phenoxymethylpenicillin. These strains are rare in Sweden, but common in some parts of Europe.
Resistance may vary geographically and information about the local resistance conditions should be obtained from a local microbiology laboratory.
Phenoxymethylpenicillin is water soluble and acid stable and is absorbed approximately by 50%. After administering single doses of 800 mg to adults in a fasted state, peak serum concentrations of about 10 micrograms/mL are reached after 0.5-1 hours. Concomitant food intake results in reduced absorption and lower peak serum concentrations. The biological halflife in serum is approximately 30 minutes and the protein binding rate is approximately 80%. Phenoxymethylpenicillin is excreted primarily in the urine, where 30-50% of a given dose can be shown in an antibacterial active form within 8 hours.
There are no preclinical data relevant to safety beyond those already included in the Summary of Product Characteristics.
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