Monepantel

Monepantel	Last updated: 07/09/2025
(Also known as: AAD 1566)

GENERAL INFORMATION

Description

A broad spectrum anthelmintic veterinary drug

Examples of veterinary uses

Used to control and treat gastro-intestinal roundworms

Examples of species treated

Sheep; Goats

Approval status

VMR 2013/2033 approval status (GB/UK)

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

EU Regulatory approval status

Approved

Chemical structure

Isomerism

Monepantel exhibits stereoisomerism, specifically chirality, due to the presence of a chiral centre in its molecular structure. The molecule contains a carbon atom bonded to four distinct groups, making it optically active and giving rise to two enantiomers: the (S)-enantiomer and the (R)-enantiomer. Importantly, only the (S)-enantiomer of monepantel has been shown to possess potent anthelmintic activity against gastrointestinal nematodes.

Chemical formula

C₂₀H₁₃F₆N₃O₂S

Canonical SMILES

CC(COC1=C(C=CC(=C1)C#N)C(F)(F)F)(C#N)NC(=O)C2=CC=C(C=C2)SC(F)(F)F

Isomeric SMILES

C[C@@](COC1=C(C=CC(=C1)C#N)C(F)(F)F)(C#N)NC(=O)C2=CC=C(C=C2)SC(F)(F)F

International Chemical Identifier key (InChIKey)

WTERNLDOAPYGJD-GOSISDBHSA-N

International Chemical Identifier (InChI)

InChI=1S/C20H13F6N3O2S/c1-18(10-28,11-31-16-8-12(9-27)2-7-15(16)19(21,22)23)29-17(30)13-3-5-14(6-4-13)32-20(24,25)26/h2-8H,11H2,1H3,(H,29,30)/t18-/m1/s1

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
monepantel	-

General status

Veterinary substance type

Nematicide, Antiparasitic, Anthelmintic, Medicinal drug

Substance groups

Amino-acetonitrile derivative

Minimum active substance purity

Known relevant impurities

Substance origin

Synthetic

Mode of action

Paralyses worms by attacking a previously undiscovered receptor - Hco-MPTL-1 - only present in nematodes

Molecular targets

[Nicotinic acetylcholine receptor, Blocker]

CAS RN

887148-69-8

EC number

CIPAC number

US EPA chemical code

PubChem CID

Therapeutic Class

Antiparasitic products, insecticides & repellents: anthelmintics

ATCvet Code

QP52AX09

Controlled Drug?

Regulation 37/2010 MRL Classification

Allowed substance (Table 1: Ovine, Caprine)

Molecular mass

473.39

PIN (Preferred Identification Name)

IUPAC name

N-(2-cyano-1[(2S)-5-cyano-2-(trifluoromethyl)phenoxy)propan-2-yl)-4-(trifluoromethylsulfanyl)benzamide

CAS name

N-[(1S)-1-cyano-2-(5-cyano-2-fluoromethylphenoxy)-1-methylethyl]-4-trifluoromethylsulfanylbenzamid

Forever chemical

Other status information

Relevant Environmental Water Quality Standards

Physical state

White powdery solid

Commercial

Property

Value

Availability status

Current

Introduction & key dates

early 2000s, first synthesised; 2009, first registered New Zealand

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

Elanco GmbH
Novartis

Example products using this active

Zolvix Oral Solution

Formulation and application details

Usually supplied as a non-aqueous solution for oral drench

Commercial production

The production of monepantel involves a carefully designed multi-step organic synthesis. One key route begins with 3-(2-oxo-propoxy)-4-(trifluoromethyl)benzonitrile, which reacts with ammonia in methanol to form an intermediate amide. This is followed by a tert-butyl nitration step catalysed by palladium acetate, introducing the necessary side chain. After separation and drying, the crude hydrochloride is obtained and then purified through recrystallisation in water and isopropanol, with final alkaline adjustment using ammonia water to yield the active (S)-enantiomer of monepantel.

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)

0.08

Low

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

6900

Propylene glycol

7300

n-Octanol

60700

Ethanol

175000

Dichloromethane

Melting point (°C)

145

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

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

2.82 X 10⁰⁴

Calculated

Log P

4.45

High

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.468

Dissociation constant pKa) at 25 °C

Vapour pressure at 20 °C (mPa)

2.8 X 10^-06

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

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

DT₅₀ ranges 38-146 days, rate depends on sand fraction in soil: less sand = faster degradation

Manure DT₅₀ (days)

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Stable

Note

Stable under normal environmental conditions

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

Value

Stable

Note

Stable under normal environmental conditions

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)

Non-mobile

K_oc (mL g⁻¹)

7481

Notes and range

K_oc range 6082-8880 mL g⁻¹, Soils=5

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

0.25

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

monepantel sulfone

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 2000

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)

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)

2.4

Eisenia foetida 56 day

Moderate

Soil micro-organisms

[No impact up to 0.3 mg kg⁻¹ soil]

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)

Non-toxic

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)

Non-toxic

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)

Non-toxic

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)

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 2000

Rat

Low

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

2000

Rat

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

May be absorbed through the skin

Mammalian dose elimination route and rate

Excretion was mainly via the faeces as metabolites following intravenous administration, but over 50% remains in unchanged form following oral administration

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 and kidney 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

monepantel

French

monepantel

German

Danish

Italian

Spanish

Greek

Polish

Swedish

Hungarian

Dutch

Norwegian

Record last updated:	07/09/2025
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