Methicillin, also known as Meticillin, is a semisynthetic beta-lactam antibiotic belonging to the penicillin class. It was developed as a penicillinase-resistant antibiotic, particularly for infections caused by penicillinase-producing Staphylococcus species. Methicillin is not acid-stable and was administered by injection.
Methicillin works by binding to penicillin-binding proteins (PBPs) and inhibiting the transpeptidation step required for bacterial cell-wall synthesis. This results in disruption of bacterial cell-wall integrity and ultimately bacterial cell death.
Methicillin is a specialized beta-lactam antibiotic API relevant to pharmaceutical research, microbiological studies and antibacterial drug development.
CAS Number: 61-32-5
Molecular Formula: C17H20N2O6S
Molecular Weight: 380.40 g/mol
IUPAC Name: (2S,5R,6R)-6-[(2,6-dimethoxybenzoyl)amino]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid
Synonyms: Methicillin, Meticillin, Methycillin, Metacillin
Drug Class: Penicillin / Beta-Lactam Antibiotic
Therapeutic Class: Antibacterial
Therapeutic Area: Infectious Diseases
Molecule Type: Semisynthetic Small-Molecule Antibiotic
PubChem identifies 61-32-5 as the CAS number and 380.4 g/mol as the molecular weight.
Methicillin inhibits bacterial cell-wall synthesis by binding to penicillin-binding proteins. It interferes with the transpeptidation reaction responsible for cross-linking peptidoglycan chains.
This results in:
Methicillin has historically been associated with treatment and research involving:
Methicillin is primarily important today as a historical/reference antibiotic and microbiological research compound. The emergence of methicillin-resistant Staphylococcus aureus (MRSA) made methicillin resistance an important clinical microbiology marker, and methicillin itself is no longer routinely used therapeutically in many settings.
Historically, methicillin was administered parenterally, as it is inactivated by gastric acid and is therefore not suitable for effective oral administration.
Methicillin is also encountered as Methicillin Sodium, a sodium salt/hydrated pharmaceutical form. PubChem lists Methicillin Sodium with CAS 7246-14-2, molecular formula C17H21N2NaO7S, and molecular weight 420.4 g/mol.
Typical Methicillin API quality control may include:
Store Methicillin API in a tightly closed pharmaceutical container under validated storage conditions, protected from excessive moisture, heat and direct light.
Methicillin is particularly relevant to:
| Parameter | Specification |
|---|---|
| Appearance | White crystalline powder or crystals |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| 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% |