TYROTHRICIN

Absorption

The lack of water solubility prevents absorption of tyrothricin through the skin. It is not used through other routes due to toxicity concerns .

Toxicity

The components of tyrothricin are capable of disrupting eukaryotic cell membranes at high concentrations resulting in toxicity . This manifests as hemolysis in systemic administration. It is thought that the cholesterol present in eukaryotic cells affords some resistance to the toxic mechanisms of tyrothricin . Loss of olfactory function has been noted and topical administration to the nasal mucous membranes is not recommended .

Chemical properties

White or almost white powder.

The Uses of TYROTHRICIN

Tyrothricin is a complex of two unrelated peptide families, gramicidin complex and tyrocidines complex, produced by Bacillus brevis and discovered by Dubos in 1939. Typically, tyrothricin is composed of 20% of the linear pentadecylpeptide gramicidins and 80% of cyclic decapeptide tyrocidines. Both the gramicidins and tyrocidines act by disrupting bacterial cell wall integrity, but by differing mechanisms. Tyrothricin is used clinically for bacterial skin infections in some countries.

Background

Tyrothricin is an antibiotic peptide complex produced and extracted from the aerobic Gram-positive bacillus Brevibacillus parabrevis which was previously categorized as Bacillus brevis and Bacillus aneurinolyticus . This complex is a mixture comprised of 60% tyrocidine cationic cyclic decapeptides (consisting largely of the six predominant tyrocidines, TrcA/A1, TrcB/B1, TrcC/C1, and other more minor contributors) and 40% neutral linear gramicidins (where valine-gramicidin A is often the major gramicidin present, although the mixture composition can vary) . Moreover, tyrothricin possesses broad spectrum Gram-positive antibacterial and antifungal activity that has not seen many - if any - significant reportings of microbial resistance during the over 60 years of therapeutic use the complex has provided . Nevertheless, as tyrothricin is both cytolytic and hemolytic, it does demonstrate systemic toxicity , although certain formulations that are safe for human use like throat lozenges do exist .

Indications

Tyrothricin is used as an over the counter topical antibiotic.

Definition

An antibiotic produced by growth of Bacillus brevis. It consists of a mixture of antibiotics, principally gramicidin and tyrocidine. Gramicidin is the more active component. Use is generally limited to local external applications. It is active against some Gram-positive bacteria, including species of pneumococci, streptococci, and staphylococci.

brand name

Bactratycin (Wallace).

Pharmacokinetics

Tyrothricin consists of a mix of tyrocidines and gramcidins which exert a bacteriocidal effect. This clears the area of pathogenic bacteria to allow the body to heal wounds or other damage to the skin.

Metabolism

Not Available