Yohimbine

Yohimbine	Last updated: 12/09/2025
(Also known as: quebrachin)

GENERAL INFORMATION

Description

A veterinary drug extracted from the evergreen Yohimbe tree (Pausinystalia johimbe)

Examples of veterinary uses

Mainly used to reverse sedation induced by xylazine in some mammals

Examples of species treated

Dogs; Deer; Elk; Elephants

Approval status

VMR 2013/2033 approval status (GB/UK)

Not approved

EU Regulatory approval status

Not approved

Chemical structure

Isomerism

Yohimbine exhibits stereoisomerism, specifically enantiomerism, due to the presence of multiple chiral centres within its complex indole alkaloid structure. Its pentacyclic framework includes five stereogenic centres that define its three-dimensional shape. These chiral centres give rise to multiple enantiomers, which can have markedly different biological activities. In nature, yohimbine is found alongside other stereoisomers such as raubasine and corynanthine, which share similar skeletons but differ in the spatial arrangement of atoms.

Chemical formula

C₂₁H₂₆N₂O₃

Canonical SMILES

COC(=O)C1C(CCC2C1CC3C4=C(CCN3C2)C5=CC=CC=C5N4)O

Isomeric SMILES

COC(=O)[C@H]1[C@H](CC[C@@H]2[C@@H]1C[C@H]3C4=C(CCN3C2)C5=CC=CC=C5N4)O

International Chemical Identifier key (InChIKey)

BLGXFZZNTVWLAY-SCYLSFHTSA-N

International Chemical Identifier (InChI)

InChI=1S/C21H26N2O3/c1-26-21(25)19-15-10-17-20-14(13-4-2-3-5-16(13)22-20)8-9-23(17)11-12(15)6-7-18(19)24/h2-5,12,15,17-19,22,24H,6-11H2,1H3/t12-,15-,17-,18-,19+/m0/s1

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
yohimbine	-

General status

Veterinary substance type

Medicinal drug

Substance groups

Plant-derived substance: Indole alkaloid

Minimum active substance purity

Known relevant impurities

Substance origin

Natural

Mode of action

Blocks presynaptic alpha-2 adrenergic receptors

Molecular targets

[Alpha-2C adrenergic receptor, Antagonist]

CAS RN

146-48-5

EC number

205-672-0

CIPAC number

US EPA chemical code

PubChem CID

Therapeutic Class

Therapeutic products: Antidotes

ATCvet Code

QV03AB93

Controlled Drug?

Regulation 37/2010 MRL Classification

Molecular mass

354.44

PIN (Preferred Identification Name)

17α-hydroxy-yohimban-16α-carboxylic acid methyl ester

IUPAC name

methyl (1S,15R,18S,19R,20S)-18-hydroxy-1,3,11,12,14,15,16,17,18,19,20,21-dodecahydroyohimban-19-carboxylate

CAS name

17-hydroxyyohimban-16-carboxylic acid methyl ester

Global Governance status: Listed (✓) under

UK Poisons List Order 1972	Rotterdam Convention	Montreal Protocol
XNo The Poisons List Order 1972	XNo Rotterdam Convention	XNo Montreal Protocol
Stockholm Convention	OSPAR	EU Water Framework Directive
XNo Stockholm Convention	XNo OSPAR	XNo EU Water Framework Directive

Relevant Environmental Water Quality Standards

Forever chemical

Other status information

Physical state

Solid

Commercial

Property

Value

Availability status

Current

Introduction & key dates

1896, first extracted

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

Lloyd Laboratories
Wildlife Laboratories

Example products using this active

Yobine
Antagonil

Formulation and application details

Usually supplied as a solution for injection

Commercial production

Yohimbine is produced through a multi-step extraction and purification process from the bark of the Pausinystalia johimbe tree, native to Central and Western Africa. The bark is first harvested and dried, then ground into a fine powder to increase surface area for extraction. The powdered bark undergoes solvent extraction, typically using ethanol or hydrocarbon solvents, which dissolve the yohimbine alkaloids. The resulting solution is then filtered or centrifuged to remove solid residues. Further steps include acid treatment, decolorisation, and column chromatography to isolate yohimbine from other compounds. Finally, the purified extract is crystallised and dried, yielding yohimbine.

Impact on climate of production and use

Data for specific plant extracts is scarce. However, from publicly available data the carbon footprint of plant oils has been estimated at between 1.0 and 4.0 kg CO₂e per kg of product. This depends on the plant extract content, agricultural practices and processing methods used.

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

Solubility - In water at 20 °C at pH 7 (mg l⁻¹)

241

Moderate

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

Melting point (°C)

241

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

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

5.37 X 10⁰²

Calculated

Log P

2.73

Moderate

Fat solubility of residues

Solubility

Data type

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

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)

Mouse

High

Mammals - Short Term Oral NOAEL (mg kg⁻¹ bw d⁻¹)

Mammals - Long Term (Chronic) Oral NOAEL (mg kg⁻¹ bw d⁻¹)

Birds - Acute LD₅₀ (mg kg⁻¹)

Birds - Short term dietary LC₅₀ (mg kg⁻¹ bw d⁻¹)

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)

Beneficial insects (Butterflies)

Contact

Notes

Oral

Notes

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)

Mouse

High

Mammals - Short Term Oral NOAEL (mg kg⁻¹ bw d⁻¹)

Mammals - Long Term (Chronic) Oral NOAEL (mg kg⁻¹ bw d⁻¹)

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

Mammals - Inhalation LC₅₀ (mg l⁻¹)

Other Mammal toxicity endpoints

Intraperitoneal LD₅₀ = 16 mg kg⁻¹

Mouse

Subcutaneous LD₅₀ = 37 mg kg⁻¹

Mouse

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

Mainly eliminated from the body through rapid hepatic metabolism. Less that 1% is excreted unchanged in the urine.

Health issues

Specific human health issues (hazard-based)

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

May cause anxiety
May cause CNS depression
May increase heart rate
May be harmful if absorbed through the skin

Handling issues

Property

Value and interpretation

General

May generate toxic or irritating fumes if heated to decomposition
IMDG Transport Hazard Class 6.1

CLP classification 2013

WHO Classification

Not listed (Not listed)

UN Number

UN1544

Waste disposal & packaging

Packaging Group II (moderate danger)

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

yohimbine

French

German

Danish

Italian

Spanish

Greek

Polish

Swedish

Hungarian

Dutch

Norwegian

Record last updated:	12/09/2025
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

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