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Metacillin: Full Drug Profile

Medically reviewed by Min Clinic Staff | Updated: January 2026

Metacillin - General Information

One of the penicillins which is resistant to penicillinase but susceptible to a penicillin-binding protein. It is inactivated by gastric acid so administered by injection. [PubChem]

 

Pharmacology of Metacillin

Metacillin (INN, BAN) or methicillin (USAN) is a narrow spectrum beta-lactam antibiotic of the penicillin class. It is no longer clinically used. Its role in therapy has been largely replaced by flucloxacillin and dicloxacillin, however the term methicillin-resistant Staphylococcus aureus (MRSA) continues to be used to describe Staphylococcus aureus strains resistant to all penicillins.

 

Additional information about Metacillin

Metacillin Indication: Used to treat infections caused by susceptible Gram-positive bacteria, particularly beta-lactamase-producing organisms such as Staphylococcus aureus that would otherwise be resistant to most penicillins. Mechanism Of Action: Like other beta-lactam antibiotics, meticillin acts by inhibiting the synthesis of bacterial cell walls. It inhibits cross-linkage between the linear peptidoglycan polymer chains that make up a major component of the cell wall of Gram-positive bacteria. It does this by binding to and competitively inhibiting the transpeptidase enzyme used by bacteria to cross-link the peptide (D-alanyl-alanine) used in peptidogylcan synthesis. Drug Interactions: Not Available Food Interactions: Not Available Generic Name: Meticillin Synonyms: (2,6-Dimethoxyphenyl)penicillin; 6-(2,6-Dimethoxybenzamido)penicillanic acid; Meticilina [inn-spanish]; Meticilline [inn-french]; Meticillinum [inn-latin]; Methicillinum; Methycillin; Meticillin Drug Category: Anti-Bacterial Agents; Penicillins Drug Type: Small Molecule; Approved Other Brand Names containing Meticillin: Dimocillin; Metacillin; Absorption: Not absorbed following oral administration. Toxicity (Overdose): Not Available Protein Binding: Not Available Biotransformation: Hepatic (20-40%). Half Life: 25-60 minutes Dosage Forms of Metacillin: Solution Parenteral Chemical 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 Chemical Formula: C17H20N2O6S Meticillin on Wikipedia: https://en.wikipedia.org/wiki/Methicillin Organisms Affected: Enteric bacteria and other eubacteria