Chlortetracycline

Chlortetracycline	Last updated: 05/09/2025
(Also known as: aureomycin ; biomycin )

GENERAL INFORMATION

Description

Broad spectrum antibiotic and antimicrobial substance isolated from the microorganism (treptomyces aureofaciens) used in veterinary products and for aquaculture. Usually formulated as the hydrochloride salt.

Examples of veterinary uses

Mainly used for the prevention of infections of superficial traumatic or surgical wounds

Examples of species treated

Agricultural livestock including: Poultry, Pigs, Cattle and Fish

Approval status

VMR 2013/2033 approval status (GB/UK)

Approved - usually available as a veterinary medicine for general sale (AVM-GSL)

EU Regulatory approval status

Approved

Chemical structure

Isomerism

Chlortetracycline exhibits complex isomerism due to its multiple chiral centres and tautomeric forms. The molecule contains several asymmetric carbon atoms that give rise to stereoisomers that differ in spatial arrangement but share the same molecular formula. Additionally, chlortetracycline undergoes tautomerism, especially in aqueous solutions and under varying pH conditions, where keto-enol shifts and epimerization at the C-4 position can occur, forming 4-epichlortetracycline and other isomeric species.

Chemical formula

C₂₂H₂₃ClN₂O₈

Canonical SMILES

CC1(C2CC3C(C(=O)C(=C(C3(C(=O)C2=C(C4=C(C=CC(=C41)Cl)O)O)O)O)C(=O)N)N(C)C)O

Isomeric SMILES

C[C@@]1([C@H]2C[C@H]3[C@@H](C(=O)C(=C([C@]3(C(=O)C2=C(C4=C(C=CC(=C41)Cl)O)O)O)O)C(=O)N)N(C)C)O

International Chemical Identifier key (InChIKey)

DHPRQBPJLMKORJ-XRNKAMNCSA-N

International Chemical Identifier (InChI)

InChI=1S/C22H23ClN2O8/c1-21(32)7-6-8-15(25(2)3)17(28)13(20(24)31)19(30)22(8,33)18(29)11(7)16(27)12-10(26)5-4-9(23)14(12)21/h4-5,7-8,15,26-27,30,32-33H,6H2,1-3H3,(H2,24,31)/t7-,8-,15-,21-,22-/m0/s1

2D structure diagram/image available?

Yes

General status

Veterinary substance type

Bactericide, Fungicide, Antimicrobial, Medicated feed additive

Other bioactivity & uses

Wood preservative; Antimicrobial; Biocide

Substance groups

Amide pesticide; Tetracycline compound

Minimum active substance purity

Known relevant impurities

Substance origin

Natural

Mode of action

Protein synthesis inhibitor

Molecular targets

[16S ribosomal RNA, Inhibitor], [30S ribosomal proteins, Inhibitor], [ADP-ribosylation factor 1, Inhibitor], [Catalase, Inhibitor], [Ephrin type-B receptor 1, Inhibitor], [Pancreatic triacylglycerol lipase, Inhibitor], [Protein-arginine deiminase type-4, Inhibitor]

CAS RN

57-62-5

EC number

200-341-7

CIPAC number

US EPA chemical code

006301

PubChem CID

54675777

Therapeutic Class

Dermatologicals: Antibiotics & chemotherapeutics for dermatological use

ATCvet Code

QD06AA52

Controlled Drug?

Regulation 37/2010 MRL Classification

Allowed substance (Table 1: All food producing species)

Molecular mass

478.88

PIN (Preferred Identification Name)

IUPAC name

(4S,4aS,5aS,6S,12aR)-7-chloro-4-(dimethylamino)-1,6,10,11,12a-pentahydroxy-6-methyl-3,12-dioxo-4,4a,5,5a-tetrahydrotetracene-2-carboxamide

CAS name

7-chlorotetracycline

Forever chemical

Other status information

Possible groundwater contaminant

Relevant Environmental Water Quality Standards

Physical state

White crystalline solid

Related substances & organisms

chlortetracycline hydrochloride

chlortetracycline calcium complex

Commercial

Property

Value

Availability status

Current

Introduction & key dates

1945, first discovered

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

Chr. Olesen Group
Aurora Industry Co. Ltd

Example products using this active

Aureomycin
Lederle
Chloromed
Chlortralim
Orecycline

Formulation and application details

Usually supplied in formualtions for oral administration and medicated feed premixes

Commercial production

Chlortetracycline is produced through a fermentation process using the bacterium Streptomyces aureofaciens. The production begins with inoculum development, where spores are cultivated in a nutrient-rich medium containing carbohydrates like sucrose and maltose, nitrogen sources such as corn-steep liquor and peanut meal, and buffering agents like calcium carbonate. Once the culture is established, it undergoes submerged aerobic fermentation at controlled temperatures (28–30 DegC) and pH (6–6.5) for several days, during which chlortetracycline is biosynthesised. After fermentation, the broth is acidified and filtered to separate the mycelium. The antibiotic is then extracted from the filtrate using solvents like 2-ethoxyethanol and purified through precipitation and crystallisation steps.

Impact on climate of production and use

As microbial-based products tend to use fermentation-based production processes rather than chemical synthesis, they typically have a lower fossil fuel input in formulation and active ingredient creation, and also have reduced downstream emissions due to biodegradability and minimal soil disruption, their life-cycle GHG emissions are expected to be low. Whilst hard and precise data is not available, broad estimates suggest that typically emissions are likely to be below 5 kg CO₂e/kg.

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

630

Moderate

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

Melting point (°C)

168.5

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

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

2.40 X 10^-01

Calculated

Log P

-0.62

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

Dissociation constant pKa) at 25 °C

4.5

Vapour pressure at 20 °C (mPa)

2.09 X 10^-23

Low volatility

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

4.8 X 10^-22

Non-volatile

Volatilisation as max % of applied dose lost

From plant surface

From soil surface

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

Surface tension (mN m⁻¹)

Refractive Index

Environmental release

Substance may enter the environment via the faeces of treated animals or by leaching from spilt medicated feed. Identified in pig manure at high concentrations implying manure implying a major release route

Degradation

Property

Value

Source; quality score; and other information

Interpretation

Soil degradation (days) (aerobic)

DT₅₀ (typical)

Moderately persistent

DT₅₀ (lab at 20 °C)

DT₅₀ (field)

DT₉₀ (lab at 20 °C)

DT₉₀ (field)

Note

General literature DT₅₀ range >30 days (R3)

Manure DT₅₀ (days)

44% lost after 30 days

Soil and poultry manure at 30°C decreases with decreasing temp. DT₅₀ range 0.1-56 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)

K_oc (mL g⁻¹)

Notes and range

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)

Low risk

Based on LogP < 3

Low risk

CT₅₀ (days)

Known metabolites

None

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)

> 0.89

Unknown species

Moderate

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)

128

Daphnia magna

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) (EC₅₀)

1.62

Lemna gibba

Moderate

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

Algae - Acute (growth rate, fresh; mg l⁻¹) (EC₅₀)

3.1

Raphidocelis subcapitata

Moderate

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

Mesocosm study data

NOEAEC mg l⁻¹

Marine bivalves

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

Intraperitoneal LDLo = 335 mg kg⁻¹

Rat

Intravenous LD₅₀ = 118 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

Mainly eliminated in the faeces

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

No data found

; ; ; ;

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

No further information available

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

chlortetracycline

French

chlortetracycline

German

Danish

Italian

Spanish

clortetraciclina

Greek

Polish

Swedish

Hungarian

Dutch

Norwegian

Record last updated:	05/09/2025
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