Chloramphenicol

Chloramphenicol	Last updated: 06/09/2025
(Also known as: chloromycetin; amphenicol; chlornitromycin; CAF; D-chloramphenicol ; CAM)

GENERAL INFORMATION

Description

An antiobic drug effective against a wide variety of gram-positive and gram-negative bacteria, including most anaerobic organisms

Examples of veterinary uses

Typically used to treat skin infections, wound infections, bone infections, intestinal tract infections and pneumonia

Examples of species treated

Cats; Dogs

Approval status

VMR 2013/2033 approval status (GB/UK)

Not approved

EU Regulatory approval status

Not approved

Chemical structure

Isomerism

Chloramphenicol exhibits optical isomerism, specifically diastereomerism and enantiomerism, due to the presence of two chiral centres in its propanediol side chain. These chiral centres allow for the existence of four stereoisomers: two pairs of enantiomers and two diastereomers. Among these, only the D-(-)-threo isomer, with the (1R,2R) configuration, is biologically active and used therapeutically. The other three isomers lack significant antibacterial activity and are removed during synthesis or purification.

Chemical formula

C₁₁H₁₂Cl₂N₂O₅

Canonical SMILES

C1=CC(=CC=C1C(C(CO)NC(=O)C(Cl)Cl)O)[N+](=O)[O-]

Isomeric SMILES

C1=CC(=CC=C1[C@H]([C@@H](CO)NC(=O)C(Cl)Cl)O)[N+](=O)[O-]

International Chemical Identifier key (InChIKey)

WIIZWVCIJKGZOK-RKDXNWHRSA-N

International Chemical Identifier (InChI)

InChI=1S/C11H12Cl2N2O5/c12-10(13)11(18)14-8(5-16)9(17)6-1-3-7(4-2-6)15(19)20/h1-4,8-10,16-17H,5H2,(H,14,18)/t8-,9-/m1/s1

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
chloramphenicol	-

General status

Veterinary substance type

Antibiotic, Antimicrobial, Antibacterial, Medicinal drug

Substance groups

Amphenicol

Minimum active substance purity

>98%

Known relevant impurities

Substance origin

Synthetic

Mode of action

Broad-spectrum, inhibits bacterial protein synthesis

Molecular targets

[50S ribosomal protein L16, Antagonist], [Dr hemagglutinin structural subunit, Antagonist], [Complement decay-accelerating factor]

CAS RN

56-75-7

EC number

200-287-4

CIPAC number

US EPA chemical code

PubChem CID

5959

Therapeutic Class

Antiinfectants for systemic use: Antibacterials for intramammary use; Sensory organs: Ophthalmologicals

ATCvet Code

QJ51BA01; QS01AA01

Controlled Drug?

Regulation 37/2010 MRL Classification

Prohibited

Molecular mass

323.13

PIN (Preferred Identification Name)

IUPAC name

2,2-dichloro-N-[(1R,2R)-2-hydroxy-1-(hydroxymethyl)-2-(4-nitrophenyl)ethyl]acetamide

CAS name

Forever chemical

Other status information

Evidence of use in third world countries

Relevant Environmental Water Quality Standards

Physical state

Colourless to pale yellow solid

Commercial

Property

Value

Availability status

Introduction & key dates

1947, first isolated

Example manufacturers & suppliers of products using this active now or historically

Pharmacia Animal Health Ltd

Example products using this active

Chloromycetintm Redidrops

Formulation and application details

Supplied in a variety of formulations including ear drops, eye drops, tablets and capsules

Commercial production

Chloramphenicol is produced synthetically through a multi-step chemical process that begins with a precursor such as 4-nitroacetophenone. This compound undergoes bromination to form bromo-4-nitroacetophenone, which is then converted into an aminoketone via a quaternary salt intermediate. The aminoketone is acylated and subsequently modified through acylmethylation and reduction to yield a racemic mixture of threo- and erythro-isomers of 2-acetamido-1-(4-nitrophenyl)-1,3-propanediol. The acetyl group is hydrolysed, and the desired D-threo isomer is isolated using camphor-D-sulfonic acid to form separable salts. Finally, the amino group is acylated with dichloroacetic acid methyl ester, producing the active chloramphenicol molecule

Impact on climate of production and use

Published GHG data is not available for most pharmaceuticals. However, according to industry, global averages suggest producing 1 kg of a typical active pharmaceutical ingredient can range from 10 to 100 kg CO₂e for small molecule drugs and potentially up to 1000 kg CO₂e for complex biologicals such as vaccines, depending on the drug type, its formulation, complexity of synthesis, solvent recovery, and energy sources used.

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

Solubility - In water at 20 °C (mg l⁻¹)

2500

High

Solubility - In organic solvents at 20 °C (mg l⁻¹)

150800

Propylene glycol

Melting point (°C)

151

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

Flashpoint (°C)

Octanol-water partition coefficient at pH 7, 20 °C

1.38 X 10⁰¹

Calculated

Log P

1.14

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

Dissociation constant pKa) at 25 °C

Vapour pressure at 20 °C (mPa)

2.30 X 10^-07

Low volatility

Henry's law constant at 25 °C (Pa m³ mol⁻¹)

Volatilisation as max % of applied dose lost

From plant surface

From soil surface

Maximum UV-vis absorption L mol⁻¹ cm⁻¹

max @ 278nm

Surface tension (mN m⁻¹)

Refractive Index

Environmental release

Degradation

Property

Value

Source; quality score; and other information

Interpretation

Soil degradation (days) (aerobic)

DT₅₀ (typical)

DT₅₀ (lab at 20 °C)

DT₅₀ (field)

DT₉₀ (lab at 20 °C)

DT₉₀ (field)

Note

Manure DT₅₀ (days)

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Note

Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7

Value

Note

Water-sediment DT₅₀ (days)

Water phase only DT₅₀ (days)

Sediment phase only DT₅₀ (days)

Air degradation

As this parameter is not normally measured directly, a surrogate measure is used: ‘Photochemical oxidative DT₅₀’. Where data is available, this can be found in the Fate Indices section below.

Decay in stored produce DT₅₀

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d (mL g⁻¹)

Moderately mobile

K_oc (mL g⁻¹)

Notes and range

Estimated

Freundlich

K_f (mL g⁻¹)

K_foc (mL g⁻¹)

¹/_n

Notes and range

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

Bio-concentration factor

BCF (l kg⁻¹)

CT₅₀ (days)

Known soil and groundwater metabolites

None

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

d-threo-2-amino-1-(p-nitrophenyl)-1,3-propanediol

Humans; Rat

chloramphenicol-beta-d-glucuronide

chloramphenicol 3-glucuronide

Humans; Rat

2-amino-1-(p-nitrophenyl)-1,3-propanediol

unknown

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

1500

Mouse

Moderate

Mammals - Short term dietary NOEL

(mg kg⁻¹)

(ppm diet)

Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)

Birds - Acute LD₅₀ (mg kg⁻¹)

Birds - Short term dietary (LC₅₀/LD₅₀)

Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)

Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)

Earthworms - Chronic NOEC, reproduction (mg kg⁻¹)

Soil micro-organisms

Collembola

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

Non-target plants

Vegetative vigour ER₅₀ (g ha⁻¹)

Seedling emergence ER₅₀ (g ha⁻¹)

Honeybees (Apis spp.)

Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Unknown mode acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Chronic

Notes

Bumblebees (Bombus spp.)

Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Mason bees (Osmia spp.)

Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Other bee species (1)

Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)

Mode of exposure

Other bee species (2)

Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)

Mode of exposure

Beneficial insects (Ladybirds)

Beneficial insects (Lacewings)

Beneficial insects (Parasitic wasps)

Beneficial insects (Predatory mites)

Beneficial insects (Ground beetles)

Aquatic ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Temperate Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

1828

Anguilla japonica

Low

Temperate Freshwater Fish - Chronic 21 day NOEC (mg l⁻¹)

Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

Temperate Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)

3360

Daphnia magna as umol/litre

Low

Temperate Freshwater Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)

Tropical Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)

Aquatic crustaceans - Acute 96 hour LC₅₀ (mg l⁻¹)

Sediment dwelling organisms - Acute 96 hour LC₅₀ (mg l⁻¹)

Sediment dwelling organisms - Chronic 28 day NOEC, static, water (mg l⁻¹)

Sediment dwelling organisms - Chronic 28 day NOEC, sediment (mg kg⁻¹)

Aquatic Plants (free-floating, fonds growth, fresh) - 7 day (mg l⁻¹)

Aquatic plants (rooted, growth rate, fresh) - 14 day (mg l⁻¹)

Algae - Acute (growth rate, fresh; mg l⁻¹)

Algae - Chronic (growth rate, fresh; mg l⁻¹)

Mesocosm study data

NOEAEC mg l⁻¹

Marine bivalves – Acute LC₅₀, mortality (mg l⁻¹)

323

Crassostrea gigas Larva

HUMAN HEALTH AND PROTECTION

General

Property

Value

Source; quality score; and other information

Interpretation

Threshold of Toxicological Concern (Cramer Class)

High (class III)

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

1500

Mouse

Moderate

Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)

Mammals - Inhalation LC₅₀ (mg l⁻¹)

Other Mammal toxicity endpoints

Subcutaneous LD₅₀ > 5000 mg kg⁻¹

Rat

Intravenous LD₅₀ = 171 mg kg⁻¹

Rat

ADI - Acceptable Daily Intake (mg kg⁻¹ bw day⁻¹)

ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)

AAOEL - Acute Acceptable Operator Exposure Level (mg kg⁻¹ bw day⁻¹)

AOEL - Acceptable Operator Exposure Level - Systemic (mg kg⁻¹ bw day⁻¹)

Dermal penetration studies (%)

Dangerous Substances Directive 76/464

Exposure Routes

Public

Occupational

Mammalian dose elimination route and rate

In humans metabolised and approx. half excreted in urine within 8hr of an oral dosing as the glucuronide conjugate; only 6% was excreted as the unchanged parent.

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

No data found

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

No data found

Respiratory tract irritant

Skin irritant

Skin sensitiser

No data found

Eye irritant

Phototoxicant

No data found

General human health issues

IARC Group 2A carcinogen; US NTP - suspected carcinogen; OSHA - anticipated human carcinogen
Can induce childhood leukemia and aplastic anemia, although these effects are rare
Toxic if ingested
Blood, kidneys and liver toxicant

Handling issues

Property

Value and interpretation

General

No information available

CLP classification 2013

WHO Classification

Not listed (Not listed)

UN Number

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

chloramphenicol

French

German

Danish

Italian

cloroamfenicolo

Spanish

cloramfenicol

Greek

Polish

chloromycetny

Swedish

Hungarian

Dutch

Norwegian

Record last updated:	06/09/2025
Contact:	aeru@herts.ac.uk
Please cite as:	Lewis, K.A., Tzilivakis, J., Warner, D. and Green, A. (2016) An international database for pesticide risk assessments and management. Human and Ecological Risk Assessment: An International Journal, 22(4), 1050-1064. DOI: 10.1080/10807039.2015.1133242