With the discovery of the penicillin nucleus, 6-APA, it became possible to synthesize new penicillins by the introduction of side chains . Phenoxyethylpenicillin, an oral penicillin analogous to penicillin V, was the ﬁrst penicillin produced semisynthetically. Penicillin V and phenethicillin are very similar, but differ slightly in their antibacterial activity and absorption from the gastrointestinal tract. They are both formulated as potassium salts. Penicillin V is the only phenoxypenicillin commonly available.
For the treatment of mild to moderately severe infections (e.g. dental infection, infections in the heart, middle ear infections, rheumatic fever, scarlet fever, skin infections, upper and lower respiratory tract infections) due to microorganisms.
Pheneticillin is usually used only for the treatment of mild to
moderate infections, and not for severe or deep-seated infections since
absorption can be unpredictable. Except for the treatment or prevention of
infection with Streptococcus pyogenes (which is uniformly sensitive to
penicillin), therapy should be guided by bacteriological studies (including
sensitivity tests) and by clinical response. Patients treated initially with
parenteral benzylpenicillin may continue oral treatment with
pheneticillin once a satisfactory clinical response has been obtained.
Dosage and Administration
The comparative pharmacodynamics and clinical pharmacokinetics of phenoxymethylpenicillin and pheneticillin have been reported .
The relative AUC (mg l-1 h) for phenoxymethylpenicillin (PM), acid and potassium salt, and pheneticillin (PE), potassium salt, after oral administration, calculated from published data is reported in the table below:
Mechanism of Action
By binding to specific penicillin-binding proteins (PBPs) located inside the bacterial cell wall, penicillin V inhibits the third and last stage of bacterial cell wall synthesis. Cell lysis is then mediated by bacterial cell wall autolytic enzymes such as autolysins.
Other pharmacological effects
The inhibitory effect of Phenoxymethylpenicillin on the growth of S. aureus in vitro, is 2.13 times more potent than pheneticillin.
The potency ratio of Phenoxymethylpenicillin to pheneticillin against S. aureus in an experimental mouse-thigh infection is only 1.25 to 1. This is explained by the difference in the AUC after subcutaneous administration of Phenoxymethylpenicillin (0.47mg l-1 h) and pheneticillin (0.92mg l-1 h).
CAS number: 147-55-7 EINECS:
Molecular Formula: C17H20N2O5S
Average mass: 364.416107 Da
Monoisotopic mass: 364.109283 Da
Systematic name: (2S,5R,6R)-3,3-Dimethyl-7-oxo-6-[(2-phenoxypropanoyl)amino]-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid
Std. InChI: 1S/C17H20N2O5S/c1-9(24-10-7-5-4-6-8-10)13(20)18-11-14(21)19-12(16(22)23)17(2,3)25-15(11)19/h4-9,11-12,15H,1-3H3,(H,18,20)(H,22,23)/t9?,11-,12+,15-/m1/s1
1. Batchelor F.R., Doyle F.P., Nayler J.H.C., Rolinson G.N. "Synthesis of penicillin: 6-aminopenicillanic acid in penicillin fermentation". Nature 183: 257, (1959).
2. D. OVERBOSCH, H. MATTIE &
R. van FURTH. "Comparative pharmacodynamics and clinical pharmacokinetics of
phenoxymethylpenicillin and pheneticillin". Br. J. clin. Pharmac. 19,
Send mail to
questions or comments about this web site.