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Triclabendazole (Ref: CGA 89317)
Last updated: 26/04/2024
(Also known as: CGA 89317)
GENERAL INFORMATION
Description
A benzimidazole anthelmintic used in veterinary medicine
Availability status
Current
Introduction & key dates
1980s, first introduced
Examples of veterinary uses
Used for the control of liver flukes, scabies causing mites, bloodsuck lice and fly larvae
Examples of species treated
Cattle; Sheep; Goats
Approval status
VMR 2013/2033 approval status (GB/UK)
Approved
EU Regulatory approval status
Approved
Chemical structure
Isomerism
-
Chemical formula
C₁₄H₉Cl₃N₂OS
Canonical SMILES
CSC1=NC2=CC(=C(C=C2N1)Cl)OC3=C(C(=CC=C3)Cl)Cl
Isomeric SMILES
No data
International Chemical Identifier key (InChIKey)
NQPDXQQQCQDHHW-UHFFFAOYSA-N
International Chemical Identifier (InChI)
InChI=1S/C14H9Cl3N2OS/c1-21-14-18-9-5-8(16)12(6-10(9)19-14)20-11-4-2-3-7(15)13(11)17/h2-6H,1H3,(H,18,19)
2D structure diagram/image available?
Yes
Cambridge Crystallographic Data Centre diagrams
Common Name Relationship Link
triclabendazole -
General status
Veterinary substance type
Anthelmintic, Antiparasitic Medicinal drug
Substance groups
Benzimidazole
Minimum active substance purity
>97%
Known relevant impurities
-
Substance origin
Synthetic
Mode of action
It binds to tubulin impairing intracellular transport mechanisms and interferes with protein synthesis.
Molecular targets
[Microtubule formation, Inhibitor]
CAS RN
68786-66-3
EC number
-
CIPAC number
-
US EPA chemical code
-
PubChem CID
-
Therapeutic Class
Antiparasitic products, insecticides & repellents: Anthelmintics
ATCvet Code
QP52AC01
Controlled Drug?
No
Regulation 37/2010 MRL Classification
Allowed substance (Table 1: Ruminants)
Molecular mass
359.66
PIN (Preferred Identification Name)
-
IUPAC name
5-chloro-6-(2,3-dichlorophenoxy)-2-(methylthio)-1H-benzimidazole
CAS name
6-chloro-5-(2,3-dichlorophenoxy)-2-methylthio-benzimidazole
Other status information
-
Relevant Environmental Water Quality Standards
-
Physical state
White to brown crystalline powder
Related substances & organisms
Formulations
Property
Product
Manufacturer
Authorisation Route
Legal Class (GB/UK)
Example products (past and present) using this active
Combinex Cattle Oral Suspension Elanco Europe Ltd UK National authorisation Prescription only medicine to be authorised by suitably qualified person (POM-VPS)
Cydectin Oral Suspension Zoertis UK Ltd GB National authorisation Prescription only medicine to be authorised by suitably qualified person (POM-VPS)
Triclafas Drench Oral Suspension Norbrook Laboratories Ltd UK National authorisation Prescription only medicine to be authorised by suitably qualified person (POM-VPS)
Formulation and application details
Usually available, often in combination with levamisole hydrochloride, as oral suspensions or as pour-on formulations
ENVIRONMENTAL FATE
Property
Value
Source; quality score; and other information
Interpretation
Solubility - In water at 20 °C (mg l⁻¹)
1.0
Q3 Q = Miscellaneous data from online sources
3 = Unverified data of known source
 Low
Solubility - In organic solvents at 20 °C (mg l⁻¹)
- - -
Melting point (°C)
175
Q3 Q = Miscellaneous data from online sources
3 = Unverified data of known source
 -
Boiling point (°C)
496
Q3 Q = Miscellaneous data from online sources
3 = Unverified data of known source
 -
Degradation point (°C)
- - -
Flashpoint (°C)
253.7
Q3 Q = Miscellaneous data from online sources
3 = Unverified data of known source
 -
Octanol-water partition coefficient at pH 7, 20 °C
P
- - -
Log P
- - -
Fat solubility of residues
Solubility
- - -
Data type
- - -
Density (g ml⁻¹)
1.59
Q3 Q = Miscellaneous data from online sources
3 = Unverified data of known source
 -
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
1.724
Q3 Q = Miscellaneous data from online sources
3 = Unverified data of known source
 -
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)
- - -
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
Kd (mL g⁻¹)
- - -
Koc (mL g⁻¹)
-
Notes and range
-
Freundlich
Kf (mL g⁻¹)
- - -
Kfoc (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
triclabendazole sulfone - Animal (Faeces) -
4-hydroxy triclabendazole - Animal (Faeces) -
2-benzimidazolone - Animal (Urine and Faeces) -
triclabendazole sulfoxide - Animal (Faeces) -
ECOTOXICOLOGY
Terrestrial ecotoxicology
Property
Value
Source; quality score; and other information
Interpretation
Mammals - Acute oral LD₅₀ (mg kg⁻¹)
> 5000
F4 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents / FAO data, IPCS INCHEM data (US EPA Databases Related to Pesticide Risk Assessment )
4 = Verified data
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)
- - -
Soil micro-organisms
- - -
Collembola
Acute LC₅₀ (mg kg⁻¹)
- - -
Chronic NOEC (mg kg⁻¹)
- - -
Non-target plants
- - -
- - -
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
- - -
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)
0.14
E3 E = Manufacturers safety data sheets
3 = Unverified data of known source
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)
- - -
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 - Acute 7 day EC₅₀, biomass (mg l⁻¹)
- - -
Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)
- - -
Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)
- - -
Mesocosm study data
NOEAEC mg l⁻¹
- - -
NOEAEC mg l⁻¹
- - -
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)
> 5000
F4 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents / FAO data, IPCS INCHEM data (US EPA Databases Related to Pesticide Risk Assessment )
4 = Verified data
Rat		 Low
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)
4000
Q3 Q = Miscellaneous data from online sources
3 = Unverified data of known source
Rat		 -
Mammals - Inhalation LC₅₀ (mg l⁻¹)
> 0.5
E3 E = Manufacturers safety data sheets
3 = Unverified data of known source
Rat 4 hr		 -
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
Mostly metabolised and excreted via urine and faeces. Also identified unchanged in breast milk.
F4 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents / FAO data, IPCS INCHEM data (US EPA Databases Related to Pesticide Risk Assessment )
4 = Verified data
 -
Health issues
Specific human health issues
Carcinogen
Genotoxic
Endocrine disruptor
XNo, known not to cause a problem
A0 A = Chromosome aberration (EFSA database)
0 = No data
;
B0 B = DNA damage/repair (EFSA database)
0 = No data
;
C0 C = Gene mutation (EFSA database)
0 = No data
;
D0 D = Genome mutation (EFSA database)
0 = No data
;
E3 E = Unspecified genotoxicity type (miscellaneous data source)
3 = Negative
XNo, known not to cause a problem
Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant
No data found
XNo, known not to cause a problem
XNo, known not to cause a problem
Respiratory tract irritant Skin irritant Skin sensitiser
✓Yes, known to cause a problem
✓Yes, known to cause a problem
 No data found
Eye irritant Phototoxicant  
✓Yes, known to cause a problem
 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
triclabendazole
French
-
German
-
Danish
-
Italian
-
Spanish
triclabendazol
Greek
-
Polish
-
Swedish
-
Hungarian
-
Dutch
-
Norwegian
-
Record last updated: 26/04/2024
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