Moxalactam

CHEMBL74632 Phase 4 Approved Small molecule

Half-Life

—

Bioavailability

—

Protein Binding

—

Molecular Weight

520.5 g/mol

LogP

-0.6

Phase

4

An oxacephem nucleus rather than the usual cephem ring sets moxalactam apart from the other third-generation cephalosporins, and that structural variation shaped both its spectrum and its downfall. Activity extended usefully across gram-negative organisms and anaerobes, a combination that was uncommon at the time of its introduction. The agent also interfered with vitamin K-dependent clotting factor synthesis, and the resulting serious bleeding episodes proved decisive: safer cephalosporins and other antibacterial agents have largely displaced it from practice. Its history is frequently cited when the haemostatic effects of the N-methylthiotetrazole side chain are discussed. The compound has the formula C20H20N6O9S and a molecular weight near 520.5 g/mol, and reached the final phase of clinical development.

This third-generation cephalosporin antibiotic with unusual oxacephem structure had good activity against gram-negative bacteria and anaerobes but was associated with serious bleeding problems due to interference with vitamin K-dependent clotting factors. It has been largely replaced by safer cephalosporins and other antibiotics.

Molecular Weight

520.5000 g/mol

LogP

-0.60

TPSA

232.00 Å²

Lipinski RO5

Fail

Therapeutic Areas

Infectious Disease

Mechanism of Action

An oxacephem (1-oxa-beta-lactam) antibacterial. Moxalactam binds penicillin-binding proteins and blocks the transpeptidation step that cross-links peptidoglycan, leaving a defective cell wall that fails under osmotic stress. Its N-methylthiotetrazole side chain separately interferes with vitamin K-dependent clotting factor synthesis and with platelet function, which is the origin of the bleeding that led to its withdrawal.

Pharmacokinetics (PK)

Pharmacodynamics (PD)

Mechanism

An oxacephem (1-oxa-beta-lactam) antibacterial. Moxalactam binds penicillin-binding proteins and blocks the transpeptidation step that cross-links peptidoglycan, leaving a defective cell wall that fails under osmotic stress. Its N-methylthiotetrazole side chain …

2D Structure

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SMILES

CO[C@@]1(NC(=O)C(C(=O)O)c2ccc(O)cc2)C(=O)N2C(C(=O)O)=C(CSc3nnnn3C)CO[C@@H]21

InChI

InChI=1S/C20H20N6O9S/c1-25-19(22-23-24-25)36-8-10-7-35-18-20(34-2,17(33)26(18)13(10)16(31)32)21-14(28)12(15(29)30)9-3-5-11(27)6-4-9/h3-6,12,18,27H,7-8H2,1-2H3,(H,21,28)(H,29,30)(H,31,32)/t12?,18-,20+/m1/s1

Molecular Formula

C20H20N6O9S

HBD / HBA

4 / 13

Rotatable Bonds

9

Heavy Atoms

36

No targets recorded

Target interaction data is not yet available for this drug.

No interactions recorded

Drug interaction data is not yet available for this compound.

No side effects recorded

Side effect data is not yet available for this drug.

Frequently Asked Questions

This third-generation cephalosporin antibiotic with unusual oxacephem structure had good activity against gram-negative bacteria and anaerobes but was associated with serious bleeding problems due to interference with vitamin K-dependent clotting factors. It has been largely replaced by safer cephalosporins and other antibiotics.

An oxacephem (1-oxa-beta-lactam) antibacterial. Moxalactam binds penicillin-binding proteins and blocks the transpeptidation step that cross-links peptidoglycan, leaving a defective cell wall that fails under osmotic stress. Its N-methylthiotetrazole side chain separately interferes with vitamin K-dependent clotting factor synthesis and with platelet function, which is the origin of the bleeding that led to its withdrawal.

Yes, Moxalactam is an approved drug. It has reached clinical phase 4. It is classified as a Small molecule.

{# References & Data Sources section for drug detail pages. Renders standard pharmacological database links plus the drug's data_sources field. #}

References & Data Sources

ChEMBL — European Bioinformatics Institute (EBI). CHEMBL74632. Open-access bioactivity database.
PubChem — National Center for Biotechnology Information (NCBI). CID 47499. Chemical information database.

Data aggregated from publicly available pharmacological databases. Last updated 2026-08-20.

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Structure

Quick Data

Formula: C20H20N6O9S

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Medical Disclaimer

This content is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making medication decisions.

Data sources: ChEMBL, PubChem, DailyMed.