Boldenone undecylenate

Boldenone undecylenate	Last updated: 16/09/2025
(Also known as: androstadienolone undecylenate; 1-dehydrotestosterone)

GENERAL INFORMATION

Description

An anabolic steriod veterinary drug applied intramuscularly for its anabolic properties

Examples of veterinary uses

Used for weight gain and greater efficiency of feed conversion

Examples of species treated

Horses; Elephants

Approval status

VMR 2013/2033 approval status (GB/UK)

Not approved

EU Regulatory approval status

Not approved

Chemical structure

Isomerism

Boldenone undecylenate contains six chiral centres at carbon positions C8, C9, C10, C13, C14, and C17, giving rise to multiple stereoisomers. The biologically active form used in veterinary and research settings has the configuration (8R,9S,10R,13S,14S,17S). This precise arrangement is critical for its interaction with androgen receptors, as even small changes in stereochemistry can drastically alter its anabolic potency and receptor affinity. The undecylenate ester attached at the 17beta-hydroxyl group is typically in the trans (E) configuration at the double bond in the fatty acid chain.

Chemical formula

C₃₀H₄₄O₃

Canonical SMILES

CC12CCC3C(C1CCC2OC(=O)CCCCCCCCC=C)CCC4=CC(=O)C=CC34C

Isomeric SMILES

C[C@]12CC[C@H]3[C@H]([C@@H]1CC[C@@H]2OC(=O)CCCCCCCCC=C)CCC4=CC(=O)C=C[C@]34C

International Chemical Identifier key (InChIKey)

AHMMSNQYOPMLSX-CNQKSJKFSA-N

International Chemical Identifier (InChI)

InChI=1S/C30H44O3/c1-4-5-6-7-8-9-10-11-12-28(32)33-27-16-15-25-24-14-13-22-21-23(31)17-19-29(22,2)26(24)18-20-30(25,27)3/h4,17,19,21,24-27H,1,5-16,18,20H2,2-3H3/t24-,25-,26-,27-,29-,30-/m0/s1

2D structure diagram/image available?

Yes

General status

Veterinary substance type

Hormone

Substance groups

Hormone

Minimum active substance purity

Known relevant impurities

Substance origin

Synthetic

Mode of action

Boldenone work by stimulation of receptors molecule in muscle cells, which activate specific genes to produce proteins

Molecular targets

[Androgen receptor, Agonist]

CAS RN

13103-34-9

EC number

236-024-5

CIPAC number

US EPA chemical code

PubChem CID

11954310

Therapeutic Class

Anabolic agents for systemic use

ATCvet Code

QA14

Controlled Drug?

UK: Class C, Schedule 4 Pt2

Regulation 37/2010 MRL Classification

Molecular mass

452.67

PIN (Preferred Identification Name)

17-β-hydroxyandrosta-1,4-dien-3-one 10-undecenoate

IUPAC name

[(8R,9S,10R,13S,14S,17S)-10,13-dimethyl-3-oxo-6,7,8,9,11,12,14,15,16,17-decahydrocyclopenta[a]phenanthren-17-yl] undec-10-enoate

CAS name

Forever chemical

Other status information

DEA Schedule III

Relevant Environmental Water Quality Standards

Physical state

Yellow oil

Related substances & organisms

boldenone

boldenone acetate

Commercial

Property

Value

Availability status

Current

Introduction & key dates

1960s, developed; Circa 1965, introduced for vet use; 2013, not approved UK

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

Zoetis UK Ltd

Example products using this active

Equipoise

Formulation and application details

Supplied as an oil suspension

Commercial production

Boldenone undecylenate is synthesised through a multi-step chemical process starting with boldenone, a modified testosterone molecule featuring a double bond between carbon atoms 1 and 2. The key production step involves esterification, where boldenone’s 17beta-hydroxyl group is reacted with undecylenic acid (a long-chain unsaturated fatty acid) to form the undecylenate ester. This reaction typically uses a condensation method with activating agents like dicyclohexylcarbodiimide or acid chlorides to facilitate the bond formation.

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)

0.026

Low

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

Melting point (°C)

Boiling point (°C)

553.2

Degradation point (°C)

Flashpoint (°C)

232.2

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

1.26 X 10⁰³

Calculated

Log P

3.1

High

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.055

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

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 metabolites

None

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

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)

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

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

Urinary excretion

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

No data found

; ; ; ;

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 & kidney toxicant
Can be absorbed through the skin
Encourages the development of masculine characteristics

Handling issues

Property

Value and interpretation

General

May be combustible at high temperatrues
May react with oxidising agents

CLP classification 2013

Health: H305, H361

WHO Classification

Not listed (Not listed)

UN Number

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

boldenone undecylenate

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Polish

Swedish

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Record last updated:	16/09/2025
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