Doramectin

Doramectin	Last updated: 06/09/2025
(Also known as: UK-67994)

GENERAL INFORMATION

Description

A veterinary drug used for the treatment and control of internal parasitosis

Examples of veterinary uses

Used to manage gastrointestinal roundworms, lungworms, eyeworms, grubs, sucking lice and mange mites in cattle and other animals

Examples of species treated

Cattle; Sheep; Pigs

Approval status

VMR 2013/2033 approval status (GB/UK)

Approved - usually available as a prescription only medicine to be authorised by suitably qualified person (POM-VPS)

EU Regulatory approval status

Approved

Chemical structure

Isomerism

Doramectin exhibits complex isomerism due to its large macrocyclic lactone structure, which includes multiple chiral centres that give rise to stereoisomers such as enantiomers and diastereomers. These variations in spatial arrangement are crucial to its biological activity, as only specific isomers effectively target parasites. Additionally, doramectin can form epimers, which are stereoisomers differing at a single chiral centre and may display geometric (E/Z) isomerism around certain double bonds.

Chemical formula

C₅₀H₇₄O₁₄

Canonical SMILES

CC1C=CC=C2COC3C2(C(C=C(C3O)C)C(=O)OC4CC(CC=C(C1OC5CC(C(C(O5)C)OC6CC(C(C(O6)C)O)OC)OC)C)OC7(C4)C=CC(C(O7)C8CCCCC8)C)O

Isomeric SMILES

C[C@H]1C=C[C@]2(C[C@@H]3C[C@H](O2)C/C=C(/C([C@H](/C=C/C=C/4\CO[C@H]5[C@@]4([C@@H](C=C([C@H]5O)C)C(=O)O3)O)C)O[C@H]6C[C@@H](C([C@@H](O6)C)O[C@H]7C[C@@H]([C@H]([C@@H](O7)C)O)OC)OC)\C)O[C@@H]1C8CCCCC8

International Chemical Identifier key (InChIKey)

QLFZZSKTJWDQOS-YDBLARSUSA-N

International Chemical Identifier (InChI)

InChI=1S/C50H74O14/c1-27-13-12-16-34-26-57-47-42(51)30(4)21-37(50(34,47)54)48(53)60-36-22-35(63-49(25-36)20-19-29(3)45(64-49)33-14-10-9-11-15-33)18-17-28(2)44(27)61-41-24-39(56-8)46(32(6)59-41)62-40-23-38(55-7)43(52)31(5)58-40/h12-13,16-17,19-21,27,29,31-33,35-47,51-52,54H,9-11,14-15,18,22-26H2,1-8H3/b13-12+,28-17+,34-16+/t27-,29-,31-,32-,35+,36-,37-,38-,39-,40-,41-,42+,43-,44-,45-,46-,47+,49+,50+/m0/s1

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
Doramectin monohydrate	Variant

General status

Veterinary substance type

Antiparasitic, Endoparasitic, Acaricide, Insecticide, Anthelmintic

Substance groups

Avermectin

Minimum active substance purity

Known relevant impurities

Substance origin

Synthetic

Mode of action

Broad-spectrum, induces rapid, non-spastic paralysis in nematodes and arthropods. Glutamate-gated chloride channel (GluCl) allosteric modulator.

Molecular targets

[Glycine receptor subunit alpha-3, Agonist], [Gamma-aminobutyric-acid (GABA) receptor subunit beta-3, Agonist]

CAS RN

117704-25-3

EC number

CIPAC number

US EPA chemical code

PubChem CID

9832750

Therapeutic Class

Antiparasitic products, insecticides & repellents: Endectocides

ATCvet Code

QP54AA03

Controlled Drug?

Regulation 37/2010 MRL Classification

Allowed substance (Table 1: All mammalian food producing species)

Molecular mass

899.11

PIN (Preferred Identification Name)

IUPAC name

1'R,2S,4'S,5S,6R,8'R,10'E,12'R,13'S,14'E,20'R,21'R,24'S)-6-cyclohexyl-21',24'-dihydroxy-12'-{[(2R,4S,5S,6S)-5-{[(2S,4S,5S,6S)-5-hydroxy-4-methoxy-6-methyloxan-2-yl]oxy}-4-methoxy-6-methyloxan-2-yl]oxy}-5,11',13',22'-tetramethyl-5,6-dihydro-3',7',19'-trioxaspiro[pyran-2,6'-tetracyclo[15.6.1.14,8.020,24]pentacosane]-10',14',16',22'-tetraen-2'-one

CAS name

25-cyclohexyl-5-O-demethyl-25-de(1-methylpropyl)avermectin A1a

Forever chemical

Other status information

Relevant Environmental Water Quality Standards

UK Environment Agency non-statutory standard for the protection of aquatic life in freshwater and saltwater: 0.001 µg l⁻¹ as annual average, 0.01 µg l⁻¹ as max acceptable conc.

Physical state

Off-white crystalline solid

Related substances & organisms

abamectin

ivermectin

Commercial

Property

Product

Manufacturer

Authorisation Route

Legal Class (GB/UK)

Availability status

Current

Introduction & key dates

1975, introduced

Example products (past and present) using this active

Dectomax 10 mg/ml Solution for Injection for Cattle and Sheep

Elanco Animal Health

UK National authorisation

Prescription only medicine to be authorised by suitably qualified person (POM-VPS)

Taurador Pour-on Solution

Norbrook Laboratories Ltd

GB National authorisation

Prescription only medicine to be authorised by suitably qualified person (POM-VPS)

Formulation and application details

Available in a variety of formulations including solutions for injection and pour-on products

Commercial production

Doramectin is produced through a specialised fermentation process using genetically engineered strains of Streptomyces avermitilis. The key modification involves replacing the natural polyketide synthase (PKS) loading module with one that accepts cyclohexanecarboxylic acid (CHC) as a starter unit, which distinguishes doramectin from its parent compound, avermectin. The engineered strain is cultivated in a nutrient-rich medium, and CHC is fed during fermentation to direct biosynthesis toward doramectin. To boost yield, competing polyketide pathways are suppressed and genes like fadD17, which enhance precursor availability, are overexpressed. After fermentation, doramectin is extracted and purified through solvent extraction and chromatographic techniques to ensure pharmaceutical-grade quality.

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)

0.025

Low

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

Melting point (°C)

160.5

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

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

2.95 X 10⁰⁷

Calculated

Log P

7.47

High

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.25

Dissociation constant pKa) at 25 °C

12.42

Vapour pressure at 20 °C (mPa)

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

Peak at 244 nm with shoulders at 238 and 253 nm

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)

Moderately persistent

DT₅₀ (lab at 20 °C)

DT₅₀ (field)

DT₉₀ (lab at 20 °C)

DT₉₀ (field)

Note

Literature DT₅₀ range 61-79 days

Manure DT₅₀ (days)

Sheep faeces

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)

289

Non-mobile

K_oc (mL g⁻¹)

35900

Notes and range

Literature K_oc range 7520 (silty loam) - 86900 (silty clay loam) mL g⁻¹; K_oc = 34100 mL g⁻¹ cattle faeces

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

-1.02

Calculated

Low leachability

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

3'-O-desmethyl doramectin

Cattle (Liver, Faeces)

24-hydroxymethyl doramectin

Cattle (Liver, Faeces)

24-hydroxymethyl-3'-O-desmethyl doramectin

Cattle (Liver, Faeces)

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 1000

Rat

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)

> 2000

Colinus virginianus

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)

> 1000

Eisenia foetida

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)

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)

0.0051

Oncorhynchus mykiss

High

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)

0.0001

Daphnia magna

High

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

0.000025

Daphnia magna 48 hr NOEC

High

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

> 0.42

Danio rerio EC₅₀ Embryo

Moderate

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

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)

> 1000

Rat

Moderate

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

Mammals - Inhalation LC₅₀ (mg l⁻¹)

Other Mammal toxicity endpoints

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

Most of the administered does is eliminated in the faeces, only around 1% is lost in the urine

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

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

May cause mild tachycardia, hypotension, fever, and hypothermia

Handling issues

Property

Value and interpretation

General

Emits toxic fumes under fire conditions
IMDG Transport Hazard Class 6.1

CLP classification 2013

WHO Classification

Not listed (Not listed)

UN Number

UN2811

Waste disposal & packaging

Packaging Group III (minor danger)

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

doramectin

French

doramectina

German

Danish

Italian

Spanish

doramectina

Greek

Polish

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