Mecillinam

Updated: 2026-09-12

Overview

Mecillinam is a beta-lactam antibiotic belonging to the penicillin group, specifically classified as an amidinopenicillin. It was developed in the 1970s and shows particular efficacy against Gram-negative bacteria, especially Escherichia coli and other Enterobacteriaceae. The compound works by inhibiting bacterial cell wall synthesis through binding to penicillin-binding protein 2 (PBP-2). Unlike other penicillins, mecillinam demonstrates a unique mechanism of action that makes it particularly effective against certain resistant strains. Its clinical use is primarily focused on treating uncomplicated urinary tract infections, though its application has decreased in some regions due to the development of newer antibiotics.

Physical and Chemical Properties

Mecillinam appears as a white to off-white crystalline powder with a molecular weight of 325.42 g/mol. It is water-soluble and slightly soluble in ethanol, which influences its formulation and administration methods. The compound decomposes at temperatures around 160-165°C rather than exhibiting a true melting point. The molecular structure includes a beta-lactam ring characteristic of penicillin antibiotics, along with an amidino group that contributes to its specific antibacterial properties. The compound is relatively stable when stored properly but can degrade when exposed to moisture, heat, or extreme pH conditions.

Main Applications

The primary medical application of mecillinam is in the treatment of acute uncomplicated lower urinary tract infections, particularly those caused by susceptible strains of Gram-negative bacteria. It shows excellent activity against E. coli, the most common uropathogen, with resistance rates generally lower than for ampicillin. In some European countries, mecillinam is used as a first-line treatment for cystitis, often administered as a prodrug (pivmecillinam) to improve oral bioavailability. The antibiotic is sometimes combined with other agents in hospital settings for more complex infections, though its use in systemic infections is limited by its pharmacokinetic properties.

Safety and Storage

As with all penicillin derivatives, mecillinam carries a risk of allergic reactions in sensitive individuals, ranging from mild rashes to severe anaphylaxis. Healthcare providers should assess patients for penicillin allergy before administration. Common side effects include gastrointestinal disturbances and, rarely, hematologic abnormalities. Proper storage requires protection from light and moisture at temperatures below 25°C. The compound should be kept in tightly sealed containers, and any solutions should be used promptly after reconstitution. In laboratory or manufacturing settings, standard precautions for handling antibiotics should be followed to prevent occupational exposure.

B2B Procurement Guide

When procuring mecillinam for pharmaceutical use or research, buyers should verify the CAS number (32887-01-7) and request certificates of analysis documenting purity (typically 98-99% for research grade). Bulk pharmaceutical quantities may require additional documentation for import/export due to antibiotic regulations. Price varies significantly based on quantity, purity, and supplier qualifications. Research-grade quantities (1-100g) commonly range from $50-$200 per gram, while bulk pharmaceutical purchases may negotiate lower unit prices. Buyers should ensure suppliers comply with Good Manufacturing Practice (GMP) standards if the material is intended for drug production.