Emamectin B1b

Emamectin B1b	Last updated: 15/09/2025
(Also known as: abamectin-aminomethyl B1b)

GENERAL INFORMATION

Description

A semi-synthetic avermectin that is clinically used in veterinary medicine for its anti-helminthic and anti-parasitic activity. Normally used as the benzoate.

Examples of veterinary uses

Used for the treatment of heartworm, hookworm, threadworm and whipworm. It is also used to control sea lice in marine cage fish

Examples of species treated

Caged fish; Cats; Dogs

Approval status

VMR 2013/2033 approval status (GB/UK)

Approved - usually supplied as a prescription only medicine to be authorised by a veterinarian (POM-V)

EU Regulatory approval status

Approved

Chemical structure

Isomerism

Emamectin B1b exhibits complex stereoisomerism due to its large, polycyclic structure and numerous chiral centres. Specifically, it contains multiple asymmetric carbon atoms—each of which can exist in either R or S configuration, leading to a variety of stereoisomers. The molecule also includes conjugated double bonds, which introduce geometric (E/Z) isomerism.

Chemical formula

C₄₈H₇₃NO₁₃

Canonical SMILES

CC1C=CC=C2COC3C2(C(C=C(C3O)C)C(=O)OC4CC(CC=C(C1OC5CC(C(C(O5)C)OC6CC(C(C(O6)C)NC)OC)OC)C)OC7(C4)C=CC(C(O7)C(C)C)C)O

Isomeric SMILES

C[C@H]1/C=C/C=C/2\CO[C@H]3[C@@]2([C@@H](C=C([C@H]3O)C)C(=O)O[C@H]4C[C@@H](C/C=C(/[C@H]1O[C@H]5C[C@@H]([C@H]([C@@H](O5)C)O[C@H]6C[C@@H]([C@@H]([C@@H](O6)C)NC)OC)OC)\C)O[C@]7(C4)C=C[C@@H]([C@H](O7)C(C)C)C)O

International Chemical Identifier key (InChIKey)

DXIOOXFZLKCVHK-VAUHGISYSA-N

International Chemical Identifier (InChI)

InChI=1S/C48H73NO13/c1-25(2)42-28(5)17-18-47(62-42)23-34-20-33(61-47)16-15-27(4)43(26(3)13-12-14-32-24-55-45-41(50)29(6)19-35(46(51)58-34)48(32,45)52)59-39-22-37(54-11)44(31(8)57-39)60-38-21-36(53-10)40(49-9)30(7)56-38/h12-15,17-19,25-26,28,30-31,33-45,49-50,52H,16,20-24H2,1-11H3/b13-12+,27-15+,32-14+/t26-,28-,30-,31-,33+,34-,35-,36-,37-,38-,39-,40+,41+,42+,43-,44-,45+,47+,48+/m0/s1

2D structure diagram/image available?

Yes

General status

Veterinary substance type

Antiparasitic

Other bioactivity & uses

Bactericide

Substance groups

Micro-organism derived substance

Minimum active substance purity

Known relevant impurities

Substance origin

Mode of action

Non-systemic, acts by causing insect paralysis. Glutamate-gated chloride channel (GluCl) allosteric modulator.

Molecular targets

[Glutamate-gated chloride channel (GluCl) allosteric, Modulator]

CAS RN

121424-52-0

EC number

CIPAC number

791

US EPA chemical code

PubChem CID

Therapeutic Class

Antiparasitic products, insecticides & repellents: Avermectins

ATCvet Code

QP54AA06

Controlled Drug?

Regulation 37/2010 MRL Classification

Molecular mass

872.1

PIN (Preferred Identification Name)

IUPAC name

(10E,14E,16E)-(1R,4S,5S,6S,6R,8R,12S,13S,20R,21R,24S)-21,24-dihydroxy--6-isopropyl-5,11,13,22-tetramethyl-2-oxo-(3,7,19-trioxatetracyclo[15.6.1.1.0]pentacosa-10,14,16,22-tetraene)-6-spiro-2Œ-(5,6-dihydro-2H-pyran)-12-yl 2,6-dideoxy-3-O-methyl-4-O-(2,4,6-trideoxy-3-O-methyl-4-methylamino-α-L-lyxo-hexapyranosyl)-)-α-L-arabino-hexapyranoside

CAS name

(4R)-5-O-demethyl-25-de(1-methylpropyl)-4-deoxy-4-(methylamino)-25-(1-methylethyl)-avermectin A1a

Forever chemical

Other status information

Relevant Environmental Water Quality Standards

Physical state

White or faintly yellow powder

Related substances & organisms

emamectin benzoate

emamectin B1a

Commercial

Property

Value

Availability status

Current

Introduction & key dates

1997, introduced Israel and Japan; 1999, introduced USA

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

Syngenta
MSD Animal Health UK Ltd

Example products using this active

Tree-age
Proclaim
Affirm
Denim
Rivaive
Slice 2 Premix

Formulation and application details

Usually formulated as the benzoate. It is usually supplied as an emulsifiable concentrate and soluble granules for crops & as a trunk injection for trees. Often used as medicated pre-mix feed for animal health.

Commercial production

Emamectin B1b is produced commercially through a multi-step chemical synthesis process. The process begins with the fermentation of a specific strain of the bacterium Streptomyces avermitilis, which produces avermectin B1b as a secondary metabolite. The avermectin B1b is then chemically modified to produce emamectin B1b. This involves several steps, including oxidation and amination reactions. The resulting emamectin B1b is purified to remove any impurities and by-products. This is typically done using high-performance liquid chromatography (HPLC) or other purification techniques.

Impact on climate of production and use

There is no publicly available LCA data on GHG emissions specifically for the manufacture of emamectin B1b. However, based on similar fermentation-derived insecticides and estimated GHG emissions: are in the region of 10–25 kg CO₂e per kg of emamectin B1b.

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

Moderate

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

1.00 X 10⁰⁵

Calculated

Log P

5.0

High

Fat solubility of residues

Solubility

Soluble

Data type

Regulatory data - observed in metabolism and farm animal feeding studies

Density (g ml⁻¹)

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

Substance may enter the environment via the faeces of treated animals or by leaching from spilt medicated feed.

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 metabolites

Metabolite

Major/Minor fraction

$Click here for further information on Major/Minor fraction$

Estimated maximum occurrence fraction

Notes

N-nitroso MAB1a

Major fraction

(4R)-5-O-demethyl-4-deoxy-4-(formylmethylamino)-avermectin A1a (Ref: NOA 415692)

Major fraction

8a-hydroxy-4-deoxy-4-epi-methylamino avermectin B1a (Ref: NOA 438306)

Major fraction

(4R)-5-O-demethyl-4-deoxy-4-(methylamino)-28-oxoavermectin A1a (Ref: NOA 438307)

Major fraction

Known groundwater metabolites

None

Other known metabolites

None

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 500

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)

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 (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)

> 500

Rat

Moderate

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

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

Mammalian dose elimination route and rate

Partially metabolised and excreted mainly in the faeces

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

No data found

Eye irritant

Phototoxicant

No data found

General human health issues

May cause climical tremors

Handling issues

Property

Value and interpretation

General

Not explosive or oxidising
Not explected to auto-ignite, Not highly flammable

CLP classification 2013

Health: H301, H311, H331, H372, H318, H319
Environment: H400

WHO Classification

Not listed (Not listed)

UN Number

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

emamectin B1b

French

German

Danish

Italian

Spanish

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