Dexamethasone

Dexamethasone	Last updated: 15/09/2025
(Also known as: fluormethylprednisolone)

GENERAL INFORMATION

Description

An anti-inflammatory corticosteroid veterinary drug

Examples of veterinary uses

Used, for example, for the control of CNS inflammation in dogs and cats and for the treatment of primary bovine ketosis.

Examples of species treated

Cattle; Horses; Lamas; Elephants; Pigs; Dogs; Cats

Approval status

VMR 2013/2033 approval status (GB/UK)

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

EU Regulatory approval status

Approved

Chemical structure

Isomerism

Dexamethasone exhibits stereoisomerism, specifically diastereomerism and enantiomerism, due to the presence of multiple chiral centres in its steroid backbone. It is a synthetic glucocorticoid derived from prednisolone, with a fluorine atom at the 9alpha-position and a methyl group at the 16alpha-position, both of which contribute to its stereochemical complexity. Dexamethasone and its isomer betamethasone differ only in the configuration at the 16-position - dexamethasone has the 16alpha-methyl group, while betamethasone has it in the 16beta-position.

Chemical formula

C₂₂H₂₉FO₅

Canonical SMILES

CC1CC2C3CCC4=CC(=O)C=CC4(C3(C(CC2(C1(C(=O)CO)O)C)O)F)C

Isomeric SMILES

C[C@@H]1C[C@H]2[C@@H]3CCC4=CC(=O)C=C[C@@]4([C@]3([C@H](C[C@@]2([C@]1(C(=O)CO)O)C)O)F)C

International Chemical Identifier key (InChIKey)

UREBDLICKHMUKA-CXSFZGCWSA-N

International Chemical Identifier (InChI)

InChI=1S/C22H29FO5/c1-12-8-16-15-5-4-13-9-14(25)6-7-19(13,2)21(15,23)17(26)10-20(16,3)22(12,28)18(27)11-24/h6-7,9,12,15-17,24,26,28H,4-5,8,10-11H2,1-3H3/t12-,15+,16+,17+,19+,20+,21+,22+/m1/s1

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
dexamethasone	-

General status

Veterinary substance type

Anti-inflammatory

Substance groups

Corticosteroid

Minimum active substance purity

Known relevant impurities

Substance origin

Synthetic

Mode of action

Unbound dexamethasone crosses cell membranes and binds to specific cytoplasmic receptors leading to a reduction in inflammation

Molecular targets

[Glucocorticoid receptor, Agonist], [Nuclear receptor 0B1, stimulator], [Annexin A1, stimulator], [Nitric oxide synthase, inducible, Negative modulator]

CAS RN

50-02-2

EC number

200-003-9

CIPAC number

US EPA chemical code

PubChem CID

Therapeutic Class

Alimentary tract & metabolism; Cardiovascular system; Dematologicals; Systemic hormone preparations excluding sex hormones & insulins; Respiratory system; Sensory organs

ATCvet Code

QA01AC02; QC05AA09; QD07AB19; QH02AB02; QR01AD03; QS01BA01; QS02BA06; QS03BA01

Controlled Drug?

Regulation 37/2010 MRL Classification

Allowed substance (Table 1 Bovine, Caprine, Porcine, Equidae)

Molecular mass

392.46

PIN (Preferred Identification Name)

IUPAC name

8S,9R,10S,11S,13S,14S,16R,17R)-9- fluoro-11,17-dihydroxy-17-(2-hydroxyacetyl)-10,13,16- trimethyl-6,7,8,9,10,11,12,13,14,15,16,17- dodecahydro-3H-cyclopenta[a]phenanthren-3-one

CAS name

1-dehydro-16α-methyl-9α-fluorohydrocortisone

Forever chemical

Other status information

Relevant Environmental Water Quality Standards

Physical state

White crystalline powder

Commercial

Property

Value

Availability status

Current

Introduction & key dates

1958, first synthesised; 1960s, first registerations

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

Norbrook Laboratories Ltd
MSD Animal Health Ltd

Example products using this active

Colvasone Solution for Injection
Dexafort Suspension for Injection
Marbodex Aurl Ear Drops
Trovex Solution for Injection

Formulation and application details

Available in a variety of formulations including solutions for injection, chewable tables and dropper suspension solutions as ear drops

Commercial production

Dexamethasone is synthesised through a complex, multi-step chemical process starting from steroidal precursors such as 3alpha-acetoxy-16-pregnen-11,20-dione. The initial steps involve Grignard reactions using methylmagnesium bromide to introduce a methyl group at the 16alpha-position, followed by acetylation and epoxidation to modify the steroid backbone. Strategic bromination, iodination, and hydroxylation steps are used to install functional groups at key positions, including the 21-hydroxyl and 9alpha-fluoro groups that define dexamethasone’s activity. The molecule undergoes oxidation and dehydrogenation to form the characteristic 1,4-diene structure in the A-ring. A final microbiological dehydrogenation step at the C1–C2 position, along with deacetylation, yields the active dexamethasone compound.

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)

Moderate

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

1000

Ethanol

Melting point (°C)

262

Boiling point (°C)

568

Degradation point (°C)

Flashpoint (°C)

279.5

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

6.76 X 10⁰¹

Calculated

Log P

1.83

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.32

Dissociation constant pKa) at 25 °C

Vapour pressure at 20 °C (mPa)

1.18 X 10^-08

Low volatility

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

Contains chromophores that absorb at wavelengths >290nm

Surface tension (mN m⁻¹)

Refractive Index

1.591

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)

Moderately mobile

K_oc (mL g⁻¹)

240

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 and groundwater metabolites

None

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

6-beta-hydroxydexamethasone

Human (Liver)

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 3000

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

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)

0.05

Danio rerio EC₅₀ Larva

High

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)

> 3000

Rat

Low

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

Mammals - Inhalation LC₅₀ (mg l⁻¹)

Other Mammal toxicity endpoints

Intraperitoneal LD₅₀ = 54 mg kg⁻¹

Rat

Subcutaneous LD₅₀ = 14 mg kg⁻¹

Rat

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

Metablised and around 30% excreted in the urine within 4 days. Also excreted in human breast milk.

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

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

May cause hypertension
May cause retinal toxicity, glaucoma & subcapsular cataract
May cause delayed wound healing, atrophy & skin fragility

Handling issues

Property

Value and interpretation

General

Emits toxic fumes of hydrogen fluoride when heated to decomposition

CLP classification 2013

WHO Classification

Not listed (Not listed)

UN Number

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

dexamethasone

French

German

Danish

Italian

Spanish

dexametasona

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