Benzathine Benzylpenicillin molecular structure

Benzathine Benzylpenicillin

Also known as: Bicillin L-A, Extencilline, Penidure, Pendysin

CAS Number: 1538-09-6

Long-Acting Depot Penicillin (Beta-Lactam)

Pharmacopeia Standards

USPBPIPEPWHO

Mechanism of Action

The dibenzylethylenediamine salt is a poorly soluble depot form that hydrolyses slowly at the intramuscular injection site to liberate benzylpenicillin over two to four weeks. The released benzylpenicillin binds penicillin-binding proteins and blocks peptidoglycan transpeptidation. Sustained low plasma concentrations are sufficient for organisms that have never developed penicillin resistance, notably Treponema pallidum and Streptococcus pyogenes.

Technical Specifications

Generic / INN NameBenzathine Benzylpenicillin
CAS Registry Number1538-09-6
Molecular FormulaC48H56N6O8S2
Molecular Weight909.13 g/mol g/mol
Typical PurityNLT 96.0% and NMT 102.0% of total penicillins (anhydrous basis); benzathine content 24.0-27.0%
Storage ConditionsStore below 25 C in tight, light-resistant containers protected from moisture; sterile grade handled under Grade A/B conditions with nitrogen blanketing.
Shelf Life24 months for sterile grade when stored in original sealed packaging
CategoryPenicillins

Specifications are indicative and intended for sourcing reference only. Always confirm against the supplier's Certificate of Analysis and the applicable pharmacopeial monograph before issuing a purchase specification.

Typical Applications

Sterile aqueous suspension for injection (0.6 MIU, 1.2 MIU, 2.4 MIU); fixed combinations with procaine benzylpenicillin; secondary prophylaxis programmes for rheumatic heart disease.

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