Oxytetracycline hydrochloride

Oxytetracycline hydrochloride	Last updated: 16/09/2025
(Also known as: terramycin; oxytracyl; oxytetrin; terramitsin; oxitetracycline; crop antibiotic)

GENERAL INFORMATION

Description

A highly active broad spectrum antibiotic used to control infection animals diseses and bacterial pathogens

Examples of veterinary uses

Used to control gastrointestinal and respiratory diseases as well as some skin conditions including Rickettsial infections, Lupus

Examples of species treated

Calves; Non-lactating dairy cattle; Beef; Pigs; Fish; Poultry; Cats; Dogs

Approval status

VMR 2013/2033 approval status (GB/UK)

Approved - usually supplied as a prescription only medicine to be authorised by a veterinarian (POM-V)

EU Regulatory approval status

Approved

Chemical structure

Isomerism

Oxytetracycline hydrochloride exhibits stereoisomerism, particularly epimerism and tautomerism, due to its multiple chiral centres and functional groups capable of rearrangement. The molecule contains several asymmetric carbon atoms, notably at positions 4, 4a, 5, 5a, 6, and 12a, which allow for the formation of diastereomers. One common isomeric form is 4-epioxytetracycline, which arises from inversion at the C-4 position and can occur spontaneously in aqueous solutions, especially under acidic conditions. Additionally, oxytetracycline undergoes tautomerism involving its keto and enol groups, particularly in the diketone and hydroxyl regions of the tetracycline ring system. Only one stereoisomer is used therapeutically.

Chemical formula

C₂₂H₂₅ClN₂O₉

Canonical SMILES

CC1(C2C(C3C(C(=O)C(=C(C3(C(=O)C2=C(C4=C1C=CC=C4O)O)O)O)C(=O)N)N(C)C)O)O.Cl

Isomeric SMILES

C[C@@]1([C@H]2[C@@H]([C@H]3[C@@H](C(=O)C(=C([C@]3(C(=O)C2=C(C4=C1C=CC=C4O)O)O)O)C(=O)N)N(C)C)O)O.Cl

International Chemical Identifier key (InChIKey)

SVDOODSCHVSYEK-IFLJXUKPSA-N

International Chemical Identifier (InChI)

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
oxytratracycline	Parent

General status

Veterinary substance type

Bactericide, Antimicrobial, Antiseptic, Medicated feed additive

Other bioactivity & uses

Antimicrobial; Bactericide; Crop antibiotic

Substance groups

Micro-organism derived substance

Minimum active substance purity

Known relevant impurities

Substance origin

Natural

Mode of action

Broad-spectrum, protein synthesis inhibitor and binds to the 30S and 50S bacterial ribosomal subunits

Molecular targets

[30S ribosomal protein S9, Antagonist], [30S ribosomal protein S4, Antagonist], [16S rRNA, Antagonist]

CAS RN

2-58-46-0

EC number

218-161-2

CIPAC number

US EPA chemical code

PubChem CID

Therapeutic Class

Dermatologicals: Antibiotics and chemotherapeutics for dermatological use; Antiinfectants for systemic use: Antibacterials for systemic use

ATCvet Code

QD06AA03 for topical use; QJ01AA06 for systemic use; Others available

Controlled Drug?

Regulation 37/2010 MRL Classification

Allowed substance (Table 1: All food producing species)

Molecular mass

496.90

PIN (Preferred Identification Name)

(4S,4aR,5S,5aR,6S,12aR)-4-(dimethylamino)-1,5,6,10,11,12a-hexahydroxy-6-methyl-3,12-dioxo-4,4a,5,5a-tetrahydrotetracene-2-carboxamide;hydrochloride

IUPAC name

(4S,4aR,5S,5aR,6S,12aR)-4-(dimethylamino)-1,5,6,10,11,12a-hexahydroxy-6-methyl-3,12-dioxo-4,4a,5,5a-tetrahydrotetracene-2-carboxamide;hydrochloride

CAS name

Forever chemical

Other status information

Possible groundwater contaminant

Relevant Environmental Water Quality Standards

Physical state

Yellow crystalline powder

Related substances & organisms

copper sulphate

Commercial

Property

Value

Availability status

Current

Introduction & key dates

1945, discovered; 1949, marketing launch; 1950s, first vet approvals

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

Syngenta
Norbrook Laboratories Ltd
MSD Animal Health Ltd

Example products using this active

Mycoshield
Cuprimicina Agrıcola
Cuprimicın 100
Mycoject
Alamycin LA Injection
Engemycin Cutaneous Spray
Alamycin Aerosol Cutaneous Spray

Formulation and application details

Supplied as a water soluble powder for preparation as injection when used as a veterinary product. For crop protection it is used as a foliar spray

Commercial production

Oxytetracycline hydrochloride is produced through a multi-stage process that begins with fermentation using Streptomyces rimosus, a soil-dwelling bacterium known for its ability to biosynthesise tetracycline antibiotics. During fermentation, the organism converts simple carbon sources into oxytetracycline via a polyketide synthase pathway, forming a tetracyclic ring structure through sequential condensation and cyclisation reactions. After fermentation, the broth is filtered to isolate crude oxytetracycline, which is then purified through solvent extraction and crystallisation. To form the hydrochloride salt, hydrogen chloride is introduced, often in a solvent system like n-butanol and isopropanol, facilitating salt formation and recrystallisation into a stable dihydrate form.

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)

6900

High

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

Melting point (°C)

121

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

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

6.03 X 10^-02

Calculated

Log P

-1.22

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.63

Dissociation constant pKa) at 25 °C

4.5

Weak acid

Vapour pressure at 20 °C (mPa)

1.29 X 10^-19

at 25 °C

Low volatility

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

1.72 X 10^-20

at 25 °C

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 urine of treated animals. Monitoring studies have identified this substance in livestock liquid manures

Degradation

Property

Value

Source; quality score; and other information

Interpretation

Soil degradation (days) (aerobic)

DT₅₀ (typical)

Non-persistent

DT₅₀ (lab at 20 °C)

Non-persistent

DT₅₀ (field)

DT₉₀ (lab at 20 °C)

DT₉₀ (field)

Note

Literature estimates give DT₅₀ 1 to 10 wks

Manure DT₅₀ (days)

43.8

Aerobic sediment slurry; Other data DT₅₀ (1) 79 days slurry; (2) 12,0-15.4 day slurry

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)

Moderately fast

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)

698

Non-mobile

K_oc (mL g⁻¹)

52875

Notes and range

Literature data: K_d range 417-1626 mL g⁻¹, K_oc range 27792-93317 mL g⁻¹, soils=4; Other Literature data 27792-93317 generally quoted for tetracyclines (R4)

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

-0.96

Calculated

Low leachability

Bio-concentration factor

BCF (l kg⁻¹)

0.6

Mollusca

Low potential

CT₅₀ (days)

Not available

Known metabolites

None

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 4800

Rat

Low

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)

> 5620

Anas platyrhynchos

Low

Birds - Short term dietary (LC₅₀/LD₅₀)

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

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

1954

Low

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)

100

Moderate

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)

116

Oncorhynchus mykiss

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)

102

Daphnia magna

Low

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

46.2

Daphnia magna

Low

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) (EC₅₀)

0.342

Raphidocelis subcapitata

Moderate

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

0.183

Raphidocelis subcapitata

Moderate

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)

> 4800

Rat

Low

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

5700

Mouse

Mammals - Inhalation LC₅₀ (mg l⁻¹)

Other Mammal toxicity endpoints

Intraperitoneal LD₅₀ = 260 mg kg⁻¹

Mouse

Intravenous LD₅₀ = 260 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

Systemically available oxytetracycline was primarily excreted in the urine and bile

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

No data found

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

Respiratory tract irritant

Skin irritant

Skin sensitiser

Eye irritant

Phototoxicant

No data found

General human health issues

May cause hypersensitivity reactions
May cause tooth discoloration

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

oxytetracycline hydrochloride

French

oxytetracycline

German

Oxytetracyclin

Danish

oxytetracyclin

Italian

oxytetracicline

Spanish

oxitetraciclina

Greek

Polish

oksytetracyklina

Swedish

Hungarian

Dutch

Norwegian

Record last updated:	16/09/2025
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