Mezlocillin is a semisynthetic broad-spectrum penicillin antibiotic belonging to the acylureidopenicillin group. It is structurally related to ampicillin and exerts antibacterial activity by interfering with bacterial cell-wall synthesis.
Mezlocillin is particularly associated with activity against a range of Gram-positive and Gram-negative bacteria and has historically been used for serious bacterial infections. Its antibacterial action results from binding to penicillin-binding proteins (PBPs), interfering with peptidoglycan cross-linking and weakening the bacterial cell wall.
Mezlocillin is a specialized beta-lactam antibiotic API used in pharmaceutical development and manufacture. The commonly documented pharmaceutical form is Mezlocillin Sodium, which has a USP monograph and is supplied as the sodium salt.
CAS Number: 51481-65-3
Molecular Formula: C21H25N5O8S2
Molecular Weight: 539.6 g/mol
Drug Class: Beta-Lactam Antibiotic
Subclass: Acylureidopenicillin
Therapeutic Class: Antibacterial
Therapeutic Area: Infectious Diseases
Molecule Type: Semisynthetic Penicillin
For the sodium salt, Mezlocillin Sodium, the CAS number is 42057-22-7, molecular formula C21H24N5NaO8S2, and molecular weight 561.56 g/mol. The monohydrate form has molecular weight 579.58 g/mol.
Mezlocillin acts as a beta-lactam antibiotic by binding to and inhibiting bacterial penicillin-binding proteins (PBPs).
This interferes with the final stages of peptidoglycan synthesis and cross-linking, resulting in:
Mezlocillin has historically been associated with treatment of serious bacterial infections, including infections involving susceptible:
Mezlocillin has primarily been associated with parenteral pharmaceutical preparations, particularly the sodium salt. PubChem identifies Mezlocillin Sodium as having a parenteral route of administration.
For Mezlocillin Sodium, the USP monograph provides a specific potency/assay definition. USP specifies that Mezlocillin Sodium contains the equivalent of NLT 838 µg/mg and NMT 978 µg/mg of mezlocillin, calculated on the anhydrous basis.
This corresponds to approximately 83.8%–97.8% mezlocillin equivalent on an anhydrous basis, rather than a conventional 99% assay of the sodium salt.
Store Mezlocillin API or Mezlocillin Sodium under controlled pharmaceutical storage conditions, in a tightly closed container and protected from excessive moisture, heat and direct light. Exact storage conditions should follow the applicable validated stability data and product specification.
| Parameter | Specification |
|---|---|
| Appearance | White crystalline powder or crystals |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 83.8–97.8% |
| Loss on Drying | NMT 1.0% |
| Residue on Ignition | NMT 0.2% |
| Heavy Metals | NMT 10 ppm |
| Individual Impurity | NMT 0.5% |
| Total Impurities | NMT 1.0% |
| Water Content | NMT 1.0% |