Pheneticillin, also known as Phenethicillin, is a semisynthetic penicillin antibiotic belonging to the β-lactam class of antibacterial agents. It is chemically related to penicillin and acts by interfering with bacterial cell-wall synthesis through binding to penicillin-binding proteins (PBPs). Pheneticillin is classified as a narrow-spectrum, β-lactamase-sensitive penicillin.
The CAS Number of Pheneticillin is 147-55-7. Its molecular formula is C17H20N2O5S, and its molecular weight is 364.4 g/mol. Pheneticillin has also been known by synonyms including Phenethicillin, Feneticillin, Alfacilin, 1-Phenoxyethylpenicillin and Phenoxyethylpenicillin.
For pharmaceutical applications, Pheneticillin is commonly encountered as its potassium salt, Pheneticillin Potassium, also called Phenethicillin Potassium. The potassium salt has CAS Number 132-93-4, molecular formula C17H19KN2O5S, and molecular weight approximately 402.5 g/mol.
Pheneticillin Potassium is the potassium salt of the pheneticillin anion and has historically been used as an orally administered penicillin antibiotic. Regulatory and pharmaceutical references identify Pheneticillin Potassium as a recognized pharmaceutical substance and International Pharmacopoeia reference material.
Pheneticillin exerts antibacterial activity by binding to and inhibiting bacterial penicillin-binding proteins. These proteins participate in the final stages of bacterial peptidoglycan synthesis. Their inhibition weakens the bacterial cell wall and ultimately causes bacterial cell lysis.
Pheneticillin is considered β-lactamase-sensitive, meaning that organisms producing β-lactamase enzymes may demonstrate resistance through hydrolysis of the β-lactam ring. It belongs to the penicillin group of systemic antibacterial agents.
Pheneticillin contains the characteristic β-lactam and thiazolidine-related penicillin structure together with a 2-phenoxypropanamido side chain. Its molecular structure contains defined stereochemistry that is essential to its biological activity. NCATS identifies 3 defined stereocenters out of 4 stereochemical centers in its substance representation.
The free acid has a molecular weight of 364.416 g/mol, while Pheneticillin Potassium has a molecular weight of approximately 402.506 g/mol when represented as the potassium salt.
Pheneticillin and Pheneticillin Potassium require careful control of identity, potency, degradation products and stereochemical integrity because β-lactam antibiotics can be sensitive to hydrolysis and environmental conditions.
The International Pharmacopoeia historically included Pheneticillin Potassium among its reference substances, confirming its recognized pharmaceutical analytical status.
For API manufacturing, appropriate analytical controls can include chromatographic assay, related-substance testing, water or loss-on-drying determination, optical rotation where applicable, elemental impurity assessment and residual-solvent testing.
Pheneticillin free acid is reported as soluble in DMSO in research-reference material, while the potassium salt is also reported as soluble in DMSO. These research-grade values should not be confused with a pharmacopoeial pharmaceutical solubility specification.
Because Pheneticillin is a β-lactam antibiotic, storage should protect the material from conditions that may promote degradation. Commercial research material is commonly recommended to be stored under dry, dark conditions with refrigerated or frozen long-term storage. Pharmaceutical API storage should ultimately follow the validated stability and approved manufacturer specification.
Pheneticillin has historically been used for susceptible bacterial infections, including respiratory, skin and soft-tissue infections. It is classified as an antibacterial agent and belongs to the penicillin group.
Pheneticillin API and Pheneticillin Potassium are therefore relevant to pharmaceutical research, analytical standards, antibiotic development and historical penicillin formulation applications.
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| Loss on Drying | NMT 0.5% |
| Residue on Ignition | NMT 0.1% |
| Individual Impurity | NMT 0.5% |
| Total Impurities | NMT 1.0% |
| Water Content | NMT 0.5% |