Florfenicol
[CAS# 73231-34-2]

Identification

• Classification: API >> Antipyretic analgesics >> Non-steroidal anti-inflammatory drugs
• Name: Florfenicol
• Synonyms: [R-(R*, R*)]-N-[1-(Fluoromethyl)-2-hydroxy-2-(4-(methylsulforyl)phenyl)-ethyl]-2,2-dichloroacetamide; 2,2-Dichloro-N-[(1R,2S)-3-fluoro-1-hydroxy-1-(4-methylsulfonylphenyl)propan-2-yl]acetamide
• Molecular Formula: C₁₂H₁₄Cl₂FNO₄S
• Molecular Weight: 358.21
• CAS Registry Number: 73231-34-2 (76639-94-6)
• EC Number: 642-986-0
• SMILES: CS(=O)(=O)C1=CC=C(C=C1)[C@H]([C@@H](CF)NC(=O)C(Cl)Cl)O

Properties

• Solubility: 44 mg/mL (DMSO) (Expl.)
• Density: 1.5±0.1 g/cm³
• Melting point: 155 °C (Expl.)
• Index of refraction: 1.548, Calc.^*
• Boiling point: 617.5±55.0 °C (760 mmHg), Calc.^*
• Flash point: 327.3±31.5 °C, Calc.^*

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302-H312-H332-H412
• Safety Statements: P261-P264-P270-P271-P273-P280-P301+P317-P302+P352-P304+P340-P317-P321-P330-P362+P364-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Reproductive toxicity	Repr.	2	H361
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Specific target organ toxicity - repeated exposure	STOT RE	1	H372
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Chronic hazardous to the aquatic environment	Aquatic Chronic	2	H411
Acute toxicity	Acute Tox.	4	H302
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Specific target organ toxicity - repeated exposure	STOT RE	2	H373

Discovery and Applications

Florfenicol is a broad-spectrum antibiotic used primarily in veterinary medicine to treat infections in animals. It is a synthetic derivative of chloramphenicol, an antibiotic originally derived from *Streptomyces venezuelae*, but florfenicol has been modified to improve its antibacterial activity and reduce toxicity to animals. Florfenicol is effective against a wide range of gram-positive and gram-negative bacteria, making it a versatile treatment for various bacterial infections, particularly in livestock and aquaculture.

The discovery of florfenicol dates back to the late 20th century when researchers sought to develop an antibiotic that would be effective in treating infections in animals while avoiding some of the harmful side effects associated with chloramphenicol. Chloramphenicol was widely used in both human and veterinary medicine but had been linked to serious adverse effects, including bone marrow suppression. In response, florfenicol was developed by introducing a fluorine atom into the chloramphenicol structure, which enhanced its antibacterial potency and reduced its toxicity profile, particularly the risk of bone marrow toxicity.

Florfenicol's broad-spectrum activity is primarily attributed to its ability to inhibit bacterial protein synthesis. It binds to the 50S ribosomal subunit of bacteria, preventing the formation of peptide bonds, thus halting protein elongation and inhibiting bacterial growth. This mechanism of action makes florfenicol effective against a wide array of bacterial pathogens, including those responsible for respiratory, gastrointestinal, and systemic infections in animals.

One of the major applications of florfenicol is in the treatment of respiratory infections in livestock, particularly in cattle and swine. It is commonly used to treat conditions such as bovine respiratory disease (BRD), a leading cause of morbidity and mortality in cattle. Florfenicol is also used in the treatment of fish diseases, such as columnaris and furunculosis, in aquaculture. These applications are crucial for maintaining the health of animals in agricultural and aquacultural settings, where bacterial infections can lead to significant economic losses.

Florfenicol is administered primarily through injection or as a feed additive in animal husbandry. Its ability to be used in different forms, including its long-acting injectable formulation, allows for easier and more efficient treatment of infections in large groups of animals. This has made florfenicol an important tool in managing bacterial diseases in both intensive livestock farming and aquaculture, where large numbers of animals are often at risk of infection.

In addition to its veterinary applications, florfenicol has been the subject of studies exploring its potential use in human medicine. However, due to concerns about its long-term effects and the possibility of antibiotic resistance, florfenicol is not used in humans in most countries. The global use of antibiotics in animals, including florfenicol, has raised concerns about the development of antibiotic-resistant bacteria, which could pose a threat to human health. As such, regulatory agencies closely monitor the use of florfenicol and other veterinary antibiotics to ensure that they are used responsibly and in accordance with established safety guidelines.

Despite the concerns about antibiotic resistance, florfenicol remains an essential tool in veterinary medicine. Its effectiveness in treating infections and its reduced toxicity compared to its predecessor, chloramphenicol, have made it a valuable option for veterinarians in the treatment of various animal diseases. Ongoing research into the development of newer, safer, and more effective antibiotics will continue to shape the role of florfenicol in animal health.

In conclusion, florfenicol is a synthetic antibiotic that has proven to be highly effective in the treatment of bacterial infections in animals. Its development was driven by the need to provide a safer alternative to chloramphenicol, and it continues to play a critical role in the health of livestock and aquaculture. Although concerns about antibiotic resistance persist, florfenicol remains a vital tool in veterinary medicine, ensuring that infections are controlled and animal health is maintained.

References

2010. Detection of the floR Gene in a Diversity of Florfenicol Resistant Gram-Negative Bacilli from Freshwater Salmon Farms in Chile. Zoonoses and Public Health, 57(3).
DOI: 10.1111/j.1863-2378.2009.01243.x

2009. IncA/C Plasmid-Mediated Florfenicol Resistance in the Catfish Pathogen Edwardsiella ictaluri. Antimicrobial Agents and Chemotherapy, 53(2).
DOI: 10.1128/aac.01312-08

1981. In vitro antibacterial activity of fluorinated analogs of chloramphenicol and thiamphenicol. Antimicrobial Agents and Chemotherapy, 19(2).
DOI: 10.1128/aac.19.2.294