Albendazole

Albendazole	Last updated: 04/09/2025
(Also known as: SLA 3505; SKF-62979)

SUMMARY

A potent anthelmintic insecticide. It has a low aqueous solubility. Little has been published regarding its behaviour in the environment or its toxicity to fauna and flora. It is moderately toxic to humans and may cause reproduction or fertility problems. .

GENERAL INFORMATION

Description

A broad spectrum benzimidazole antiparasitic veterinary drug

Examples of veterinary uses

Primary use is as a topical pesticide for livestock for control of parasites in particular various worm infestations.

Examples of species treated

Domestic and farm animals including cattle & 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

Albendazole exhibits tautomerism, a special type of isomerism involving the reversible transfer of a proton within the molecule. Specifically, albendazole exists in two tautomeric forms: the amino form and the imino form, which differ in the position of a hydrogen atom and the arrangement of double bonds within the benzimidazole ring system.

Chemical formula

C₁₂H₁₅N₃O₂S

Canonical SMILES

CCCSC1=CC2=C(C=C1)N=C(N2)NC(=O)OC

Isomeric SMILES

International Chemical Identifier key (InChIKey)

HXHWSAZORRCQMX-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C12H15N3O2S/c1-3-6-18-8-4-5-9-10(7-8)14-11(13-9)15-12(16)17-2/h4-5,7H,3,6H2,1-2H3,(H2,13,14,15,16)

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
albendazole	-

General status

Veterinary substance type

Insecticide, Antiparasitic, Anthelmintic

Substance groups

Benzimidazole insecticide

Minimum active substance purity

>98%

Known relevant impurities

Substance origin

Synthetic

Mode of action

Causes degenerative alterations in parasite cell walls, inhibiting tubulin polymerization which results in the loss of cytoplasmic microtubules.

Molecular targets

[Tubulin alpha-3 chain, Antagonist], [Tubulin beta-2C chain, Antagonist], [Fumarate reductase flavoprotein subunit, Antagonist]

CAS RN

54965-21-8

EC number

259-414-7

CIPAC number

None allocated

US EPA chemical code

PubChem CID

2082

Therapeutic Class

Antiparasitic products, insecticides & repellents: Anthelmintics

ATCvet Code

QP52AC11

Controlled Drug?

Regulation 37/2010 MRL Classification

Allowed substance (Table 1: Ruminants)

Molecular mass

265.33

PIN (Preferred Identification Name)

IUPAC name

methyl N-(6-propylsulfanyl-1H-benzimidazol-2-yl)carbamate

CAS name

5-(propylthio)-1H-benzimidazol-2-yl, methyl ester carbamic acid

Forever chemical

Other status information

Relevant Environmental Water Quality Standards

Physical state

Off-white crystalline powder

Related substances & organisms

albendazole sulfoxide

Commercial

Property

Value

Availability status

Current

Introduction & key dates

1977, registered UK

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

Virbac Ltd
Chanelle Animal Health Ltd
Bimeda Animal Health Ltd

Example products using this active

Albenil 2.5% SC Oral Suspension
Albacert Oral Suspension
Endospec SC Oral Suspension

Formulation and application details

Usually administered orally as tablets or solution

Commercial production

The production of albendazole involves a multi-step synthesis starting from 2-nitro-5-chloroaniline as the key raw material. This compound undergoes a substitution reaction followed by condensation with halogenated n-propane to form 2-nitro-5-propylthioaniline. The nitro group is then reduced using an alkali sulphide method, yielding the corresponding amine. This intermediate is subjected to cyclisation to form the benzimidazole ring, which is central to albendazole’s structure.

Impact on climate of production and use

Data for the amount of life cycle GHGs produced by albendazole are not available in the public domain. However, whilst estimates vary, more general data suggests that between 14 and 19 kilograms of CO₂e is emitted per kilogram of insecticide produced.

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

0.56

Low

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

Melting point (°C)

209

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

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

1.86 X 10⁰¹

Calculated

Log P

1.27

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

Dissociation constant pKa) at 25 °C

10.26

pKa(2) = 2.80

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

Environmental release can occur via four main routes (i) point source releases at production sites, (ii) releases at administration location, (iii) direct releases from treated animals as parent and metabolites in manure and slurries, and (iv) inappropriate waste disposal sites

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)

Non-mobile

K_oc (mL g⁻¹)

17650

Notes and range

Literature range 7800-27500

Freundlich

K_f (mL g⁻¹)

251

Non-mobile

K_foc (mL g⁻¹)

16233

¹/_n

0.92

Notes and range

US data: K_f range 109.6-501.2 mL g⁻¹, K_foc range 7800-27500 mL g⁻¹, ¹/_n range 0.77-1.21, Soils=3

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

albendazole sulfoxide
Note: C12H15N3O3S

Human (Liver); Livestock

albendazole sulfone
Note: C12H15N3O4S

Human (Liver); Livestock

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

1320

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)

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)

86.0

Oncorhynchus mykiss

Moderate

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

Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

> 0.036

Danio rerio EC₅₀ Embryo

High

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

0.024

Daphnia magna

High

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

0.017

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)

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)

1320

Rat

Moderate

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

Mammals - Inhalation LC₅₀ (mg l⁻¹)

Other Mammal toxicity endpoints

Intravenous LD₅₀ = 265 mg kg⁻¹

Rat

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

0.005

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

Rapidly metabolised and lost via (probably) biliary excretion. Little is found in the urine.

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

Mutagenic potential
Possible tetragenic effect
Possible liver toxicant

Handling issues

Property

Value and interpretation

General

No information available

CLP classification 2013

Health: H315, H319, H335, H360, H361
Environment: H400, H410

WHO Classification

Not listed (Not listed)

UN Number

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

albendazole

French

albendazole

German

Albendazol

Danish

Italian

Spanish

albendazol

Greek

Polish

albendazol

Swedish

Hungarian

Dutch

Norwegian

Record last updated:	04/09/2025
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