Oxymorphone (Ref: EN3202)

Oxymorphone (Ref: EN3202)	Last updated: 11/09/2025
(Also known as: dihydroxymorphinone)

GENERAL INFORMATION

Description

A human and veterinary morphine derivative, opioid pain medication usually used as the hydrochloride salt

Examples of veterinary uses

Used for severe pain management and as an induction agent for sedation

Examples of species treated

Dogs; Cats; Elephants

Approval status

VMR 2013/2033 approval status (GB/UK)

Not approved

EU Regulatory approval status

Not approved

Chemical structure

Isomerism

Oxymorphone exhibits stereoisomerism, specifically chirality, due to the presence of multiple chiral centres in its morphinan backbone. The molecule contains asymmetric carbon atoms, most notably at positions 5alpha and 14beta, which define its three-dimensional configuration and biological activity. The clinically used form is the (5alpha,14beta)-isomer, which interacts selectively with mu-opioid receptors, producing potent analgesic effects. Other stereoisomers, such as the (5beta,14alpha) form, can theoretically exist but are either pharmacologically inactive or significantly less potent.

Chemical formula

C₁₇H₁₉NO₄

Canonical SMILES

CN1CCC23C4C(=O)CCC2(C1CC5=C3C(=C(C=C5)O)O4)O

Isomeric SMILES

CN1CC[C@]23[C@@H]4C(=O)CC[C@]2([C@H]1CC5=C3C(=C(C=C5)O)O4)O

International Chemical Identifier key (InChIKey)

UQCNKQCJZOAFTQ-ISWURRPUSA-N

International Chemical Identifier (InChI)

InChI=1S/C17H19NO4/c1-18-7-6-16-13-9-2-3-10(19)14(13)22-15(16)11(20)4-5-17(16,21)12(18)8-9/h2-3,12,15,19,21H,4-8H2,1H3/t12-,15+,16+,17-/m1/s1

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
oxymorphone	Hydrate

General status

Veterinary substance type

Medicinal drug: analgesic

Substance groups

Opioid

Minimum active substance purity

Known relevant impurities

Substance origin

Synthetic

Mode of action

Acts by binding to and activating the mu opioid receptor (MOR)

Molecular targets

[Mu-type opioid receptor, Agonist], [Delta-type opioid receptor, Antagonist]

CAS RN

76-41-5

EC number

200-959-7

CIPAC number

US EPA chemical code

PubChem CID

Therapeutic Class

Nervous system: Natural opium alkaloids

ATCvet Code

QN02AA11

Controlled Drug?

UK: Class A, Schedule 2; EU UN61/72, Class I

Regulation 37/2010 MRL Classification

Molecular mass

301.34

PIN (Preferred Identification Name)

4,5α-epoxy-3,14-dihydroxy-17-methylmorphinan-6-one

IUPAC name

4,5α-epoxy-3,14-dihydroxy-17-methylmorphinan-6-one

CAS name

7,8-dihydro-14-hydroxymorphinone

Forever chemical

Other status information

Relevant Environmental Water Quality Standards

Physical state

Crystalline solid

Commercial

Property

Value

Availability status

Current

Introduction & key dates

1914, first developed Germany

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

Endo Pharmaceuticals Inc., USA

Example products using this active

Opana

Formulation and application details

Supplied in a variety of formulations including immediate- and extended-release tablets, and solutions for injection

Commercial production

Oxymorphone is produced through a semi-synthetic process starting from oxycodone hydrochloride, a compound derived from thebaine, an opium alkaloid. The first step involves alkalization to convert oxycodone into its free base form. This is followed by a demethylation reaction, typically using reagents like hydrobromic acid or methionine, to remove the methyl group from the 3-position, yielding oxymorphone. The resulting compound then undergoes hydrogenation under acidic conditions to refine its structure and eliminate potentially genotoxic beta-unsaturated ketones. Finally, the purified oxymorphone is salified with hydrochloric acid to produce oxymorphone hydrochloride, the active pharmaceutical ingredient.

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)

24000

High

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

Melting point (°C)

248

Boiling point (°C)

Degradation point (°C)

248

Flashpoint (°C)

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

6.76 X 10⁰⁰

Calculated

Log P

0.83

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

Dissociation constant pKa) at 25 °C

8.17

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)

140

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 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)

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)

140

Rat

Moderate

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

Mammals - Inhalation LC₅₀ (mg l⁻¹)

Other Mammal toxicity endpoints

Intravenous LD₅₀ = 172 mg kg⁻¹

Mouse

Intraperitoneal LD₅₀ = 200 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

Highly metabolised in the liver

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

Eye irritant

Phototoxicant

No data found

General human health issues

CNS toxicant
May cause constipation, nausea, vomiting, dizziness
May cause severe allergic reactions - rash, hives, itching, difficulty breathing, chest tightness, swelling of the mouth, face, lips, tongue

Handling issues

Property

Value and interpretation

General

Not compatible with alkalies or strong oxidising materials
Ignited dusts may cause an explosion
Will emit toxic gases when heated to decomposition

CLP classification 2013

WHO Classification

Not listed (Not listed)

UN Number

Not regulated

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

oxymorphone

French

German

Danish

Italian

Spanish

oximorfona

Greek

Polish

Swedish

Hungarian

Dutch

Norwegian

Record last updated:	11/09/2025
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