Febantel

Febantel	Last updated: 15/09/2025
(Also known as: febantelum)

GENERAL INFORMATION

Description

A benzimidazole drug used as a antiparasitic veterinary treatment

Examples of veterinary uses

Used to control gastrointestinal parasites

Examples of species treated

Sheep; Cattle; Horses; Elephants; Pigeons; Dogs

Approval status

VMR 2013/2033 approval status (GB/UK)

Approved - for non-food animal use it may be supplied without a prescription by a suitable qualified person (NFA-VPS)

EU Regulatory approval status

Approved

Chemical structure

Isomerism

Febantel exhibits structural isomerism and stereoisomerism due to its complex molecular architecture. As a benzimidazole derivative with multiple functional groups, including methoxycarbonyl, phenylthio, and guanidino moieties, febantel can exist in different positional isomers, depending on the arrangement of these substituents on the aromatic rings. Additionally, the molecule contains chiral centres, particularly around the guanidino and carbamate groups, which allow for optical isomerism (enantiomers or diastereomers). These isomeric forms can influence the drug’s pharmacokinetics and biological activity. Moreover, febantel is known to exhibit polymorphism, meaning it can crystallise in more than one solid-state form, each with distinct physical properties such as solubility and stability.

Chemical formula

C₂₀H₂₂N₄O₆S

Canonical SMILES

COCC(=O)NC1=C(C=CC(=C1)SC2=CC=CC=C2)NC(=NC(=O)OC)NC(=O)OC

Isomeric SMILES

COCC(=O)NC1=C(C=CC(=C1)SC2=CC=CC=C2)N/C(=N\C(=O)OC)/NC(=O)OC

International Chemical Identifier key (InChIKey)

HMCCXLBXIJMERM-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C20H22N4O6S/c1-28-12-17(25)21-16-11-14(31-13-7-5-4-6-8-13)9-10-15(16)22-18(23-19(26)29-2)24-20(27)30-3/h4-11H,12H2,1-3H3,(H,21,25)(H2,22,23,24,26,27)

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
febantel	-

General status

Veterinary substance type

Antiparasitic

Substance groups

Benzimidazole

Minimum active substance purity

Known relevant impurities

Substance origin

Synthetic

Mode of action

Inhibits fumarate reductase in the worm, thereby blocking glucose uptake

Molecular targets

[Fumarate reductase flavoprotein subunit, Antagonist]

CAS RN

58306-30-2

EC number

261-205-0

CIPAC number

US EPA chemical code

PubChem CID

Therapeutic Class

Antiparasitic products, insecticides & repellents: Anthelmintics

ATCvet Code

QP52AC05

Controlled Drug?

Regulation 37/2010 MRL Classification

Allowed substance (Table 1: Ruminants, Porcine, Equidae)

Molecular mass

446.48

PIN (Preferred Identification Name)

IUPAC name

N-[-[2,3-bis-(methoxycarbonyl)-guanido]-5-(phenylthio)-phenyl]-2-methoxyacetamide

CAS name

dimethyl [2-[2-(2-methoxyacetamido)-4-(phenylthio)phenyl] imidocarbonyl] dicarbamate

Forever chemical

Other status information

Relevant Environmental Water Quality Standards

Physical state

White to off-white powder

Commercial

Property

Value

Availability status

Current

Introduction & key dates

Circa 1975, introduced

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

Oropharma N.V.
Krka d.d. Novo Mesto
Vetoquinol UK Ltd
Chanelle Pharmaceuticals Manufacturing Ltd

Example products using this active

Avicas Febantel Tablets
Anthelmin Plus Tablets
Drontal Tasty Bone Tablets
Frazitel Plus Tablets

Formulation and application details

Usually formulated as tablets or other forms for oral administration

Commercial production

The production of febantel involves a multi-step chemical synthesis starting from 5-chloro-2-nitroaniline, which undergoes a nucleophilic substitution with thiophenol in the presence of potassium carbonate to yield 2-nitro-5-phenylthioaniline. This intermediate is then acylated with methoxyacetyl chloride to form a nitroacetamide derivative, which is subsequently reduced using hydrazine hydrate to produce the corresponding amine. The final step involves condensation with S-methyl-N,N'-dimethoxycarbonyl isothiourea, resulting in the formation of febantel.

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)

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

Melting point (°C)

130

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

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

3.39 X 10⁰¹

Calculated

Log P

1.53

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.31

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

1.598

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)

CT₅₀ (days)

Known soil and groundwater metabolites

None

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

fenbendazole (Ref: Hoe 881v)

Animal metabolism

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 10000

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 dw soil)

Earthworms - Chronic NOEC, reproduction (mg kg⁻¹ dw soil)

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)

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)

0.22

Daphnia magna

Moderate

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)

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)

> 10000

Rat

Low

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

2000

Rabbit

Mammals - Inhalation LC₅₀ (mg l⁻¹)

Other Mammal toxicity endpoints

Subcutaneous LD₅₀ > 10000 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

In sheep 85% of given dose 85% excreted within 4 days - 19% in urine and 66% in faeces.

Health issues

Specific human health issues (hazard-based)

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

No further information available

Handling issues

Property

Value and interpretation

General

When heated to decomposition it emits very toxic fumes of NOx and SOx

CLP classification 2013

WHO Classification

Not listed (Not listed)

UN Number

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

febantel

French

febantel

German

Danish

Italian

Spanish

febante

Greek

Polish

Swedish

Hungarian

Dutch

Norwegian

Record last updated:	15/09/2025
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