Derquantel (Ref: PF-00520904)

Derquantel (Ref: PF-00520904)	Last updated: 16/09/2025
(Also known as: 2-deoxoparaherquamide)

GENERAL INFORMATION

Description

A spiroindole anthelminic veterinary drug

Examples of veterinary uses

Intended for the treatment and control of gastrointestinal parasites in sheep

Examples of species treated

Sheep

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

Derquantel exhibits stereoisomerism, specifically chirality, due to the presence of multiple asymmetric carbon atoms in its complex spiroindole structure. The substances’ chiral centres give rise to optical isomers. However, only one stereoisomer of derquantel is biologically active and used therapeutically, as the spatial arrangement of atoms is critical for its ability to bind and block nicotinic acetylcholine receptors in parasitic nematodes.

Chemical formula

C₂₈H₃₇N₃O₄

Canonical SMILES

CC1(C=COC2=C(O1)C=CC3=C2NCC34CC56CN7CCC(C7(CC5C4(C)C)C(=O)N6C)(C)O)C

Isomeric SMILES

C[C@]1(CCN2[C@]13C[C@@H]4[C@](C2)(C[C@]5(C4(C)C)CNC6=C5C=CC7=C6OC=CC(O7)(C)C)N(C3=O)C)O

International Chemical Identifier key (InChIKey)

DYVLXWPZFQQUIU-WGNDVSEMSA-N

International Chemical Identifier (InChI)

InChI=1S/C28H37N3O4/c1-23(2)10-12-34-21-18(35-23)8-7-17-20(21)29-15-26(17)14-27-16-31-11-9-25(5,33)28(31,22(32)30(27)6)13-19(27)24(26,3)4/h7-8,10,12,19,29,33H,9,11,13-16H2,1-6H3/t19-,25+,26-,27+,28-/m0/s1

2D structure diagram/image available?

Yes

General status

Veterinary substance type

Anthelmintic, Antiparasitic, Medicinal drug

Substance groups

Spiroindole

Minimum active substance purity

Known relevant impurities

Substance origin

Synthetic

Mode of action

Broad-spectrum, acts by blocking cholinergic neuromuscular transmission

Molecular targets

[Cholinergic neuromuscular transmission, Blocker]

CAS RN

187865-22-1

EC number

CIPAC number

US EPA chemical code

PubChem CID

Therapeutic Class

Antiparasitic products, Insecticides and Repellents: Anthelmintics

ATCvet Code

QP52

Controlled Drug?

Regulation 37/2010 MRL Classification

Allowed substance (Table 1: Ovine)

Molecular mass

479.61

PIN (Preferred Identification Name)

IUPAC name

(1'R,5'aS,7'R,8'aS,9'aR)-1'-hydroxy-1',4,4,8',8',11'-hexamethyl-2',3',8'a,9,9',10- hexahydrospiro[4H,8H-[1,4]dioxepino[2,3-g]indole-8,7'(8'H)-[5H,6H- 5a,9a](iminomethano)[1H]cyclopenta[f]indolizin]-10'-one

CAS name

(1S,6R,7R,9S,11R)-6-hydroxy-4',4',6,10,10,13-hexamethyl-9',10'-dihydro-4'H- spiro[3,13-diazatetracyclo[5.5.2.01,9.03,7]tetradecane-11,8'-[1,4]dioxepino[2,3-g]indol]- 14-one

Forever chemical

Other status information

Relevant Environmental Water Quality Standards

Physical state

Liquid

Related substances & organisms

abamectin

Commercial

Property

Value

Availability status

Current

Introduction & key dates

Early 2000s, discovery; 2010, first EU approvals

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

Zoetis UK Ltd

Example products using this active

Startect Oral Solution

Formulation and application details

Will be supplied in formulations suitable for oral administration

Commercial production

Derquantel is produced through a semi-synthetic process that begins with the fermentation of Penicillium simplicissimum, which naturally generates paraherquamide compounds. The key intermediate, paraherquamide, is then chemically modified through a four-step synthesis to yield derquantel. These steps include N-protection of the nitrogen atom to prevent unwanted reactions, followed by reduction to remove the 2-oxo group, then N-deprotection to restore the reactive nitrogen, and a final reduction step to complete the transformation into derquantel.

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. However, the semi-synthetic nature of the production process for this substance is likely to increase emissions.

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

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

Melting point (°C)

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

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

9.12 X 10⁰²

Calculated

Log P

2.96

Moderate

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.34

Dissociation constant pKa) at 25 °C

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

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)

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)

500

Rat as minimum symptomatic dose

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)

57.7

Oncorhynchus mykiss

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)

21.17

Daphnia magna

Moderate

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

0.044

Daphnia magna

Moderate

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)

47.1

Raphidocelis subcapitata

Low

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)

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

500

Rat as minimum symptomatic dose

Moderate

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

2000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

2.4

Rat as minimum symptomatic dose

Other Mammal toxicity endpoints

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

0.001

Dog SF=100

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)

[Pfizer OEL TWA-8 Hr: 10 ug/m3]

Dermal penetration studies (%)

Dangerous Substances Directive 76/464

Exposure Routes

Public

Occupational

Mammalian dose elimination route and rate

Extensively metabolised and the majority of the administered dose is eliminated in the faeces, much less in the urine.

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

Possible liver, kidney and thyroid toxicant
Clastogenic in vitro

Handling issues

Property

Value and interpretation

General

IMDG Transport Hazard Class 6.1

CLP classification 2013

WHO Classification

Not listed (Not listed)

UN Number

UN2902

Waste disposal & packaging

Packaging Group III (minor danger)

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

derquantel

French

German

Danish

Italian

Spanish

Greek

Polish

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