Title: Tyrothricin
CAS Registry Number: 1404-88-2
Additional Names: "Dubos crude crystals"
Trademarks: Hydrotricine (RPR); Dermotricine (Bellon); Tyri 10 (Lindopharm); Tyrosur (Engelhard KG)
Literature References: Polypeptide antibiotic mixture extracted from cultures of soil bacilli belonging to the Tyrothrix group of bacteria. Usually obtained by extracting acidified cultures of Bacillus brevis with alc and precipitating with NaCl soln. Surface, submerged, and aerated cultures are used. Tyrothricin contains from 10 to 20% gramicidin and from 40 to 60% tyrocidine. Solubility data: Weiss et al., Antibiot. Chemother. 7, 374 (1957). Function in the sporulation process: Sarkar, Paulus, Nature New Biol. 239, 228 (1972). Toxicity data: H. Sous et al., Arzneim.-Forsch. 7, 98 (1957).
Properties: Gray to brown powder, decomp 215-220°. Has 2-3% absorbed or combined moisture. Stable to light, air and temps up to 50°. Practically insol in water. Sol in alcohol (about 28 mg/ml), in methanol and in propylene glycol. One part of a 2% alcoholic soln contg 10% formaldehyde soln U.S.P. dissolves in 49 parts of water without cloudiness. Tyrothricin should not be dissolved in ether or acetone as only the gramicidin component is soluble. Soly in mg/ml at about 28°: water 2.1; isopropanol 5.6; benzene 0.30; isooctane 0.042; carbon tetrachloride 0.455; ethyl acetate 2.65; acetone 6.8; ether 3.25; dioxane 11.1; chloroform 1.6. Aqueous suspensions may be attacked by microorganisms. Solutions and emulsions should not be sterilized by heat. Incompatible with alkalies and strong acids. Tyrothricin gives a positive biuret and Hopkins-Cole test. LD50 in mice (mg/kg): >1500 s.c.; 100 i.p.; >3000 orally (Sous).
Toxicity data: LD50 in mice (mg/kg): >1500 s.c.; 100 i.p.; >3000 orally (Sous)
Therap-Cat: Topical antibacterial.
Therap-Cat-Vet: Topical antibacterial.
Keywords: Antibacterial (Antibiotics); Polypeptides.
Yam, Mexican Yellow AB Yellow OB Yingzhaosu Ylangene

Clinical data
AHFS/Drugs.com International Drug Names
Legal status  ?
CAS number 1404-88-2 YesY
ATC code D06AX08 R02AB02 S01AA05
PubChem CID 452550
KEGG D06262 YesY
Chemical data
Formula C65H85N11O13 
Mol. mass 1228,44 g·mol−1
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Tyrothricin is a cyclic polypeptide-antibiotic mixture from Bacillus brevis.[1] It is a locally effective antibiotic effective against gram-positive bacteria. It is sometimes combined with benzocaine 5 mg to provide relief from sore throats. In systemic intake it can lead to severe side effects, therefore, the use is limited to topical application.

Tyrothricin belongs to the pharmacologically related group of polypeptide antibiotic compounds including colistin, polymyxin B and bacitracin. There is no cross-resistance to these three agents.