Cloprostenol

Cloprostenol	Last updated: 16/09/2025
(Not known by any other names)

GENERAL INFORMATION

Description

Cloprostenol is an analogue of prostaglandin F2α (PGF2α) and used for its potemnt luteolytic properties

Examples of veterinary uses

Used to terminate pregnancy, induce parturition, and control the breeding pattern of a herd/flock or individual animals for effective stud management.

Examples of species treated

Cattle; Pigs; Sheep; Horses

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

Cloprostenol exhibits double bond isomerism, specifically geometric (cis-trans or E/Z) isomerism, due to the presence of multiple carbon–carbon double bonds in its unsaturated side chains. These double bonds can adopt either cis (Z) or trans (E) configurations, which significantly affect the molecule’s three-dimensional shape and biological activity. For example, isomers such as cis-delta4, trans-delta5, and cis-delta13 analogues have been synthesised and studied, with the cis-delta4 isomer showing comparable luteolytic potency to cloprostenol, while others are markedly less active. Cloprostenol is typically marketed as a racemic mixture.

Chemical formula

C₂₂H₂₉ClO₆

Canonical SMILES

C1C(C(C(C1O)C=CC(COC2=CC(=CC=C2)Cl)O)CC=CCCCC(=O)O)O

Isomeric SMILES

C1[C@@H]([C@@H]([C@H]([C@@H]1O)/C=C/[C@H](COC2=CC(=CC=C2)Cl)O)C/C=C\CCCC(=O)O)O

International Chemical Identifier key (InChIKey)

VJGGHXVGBSZVMZ-QIZQQNKQSA-N

International Chemical Identifier (InChI)

InChI=1S/C22H29ClO6/c23-15-6-5-7-17(12-15)29-14-16(24)10-11-19-18(20(25)13-21(19)26)8-3-1-2-4-9-22(27)28/h1,3,5-7,10-12,16,18-21,24-26H,2,4,8-9,13-14H2,(H,27,28)/b3-1-,11-10+/t16-,18-,19-,20+,21-/m1/s1

2D structure diagram/image available?

Yes

General status

Veterinary substance type

Fertility drug, Medicinal drug

Substance groups

Prostaglandin

Minimum active substance purity

~98%

Known relevant impurities

Substance origin

Synthetic

Mode of action

Induces in a sharp fall in progesterone levels

Molecular targets

[Prostaglandin F2-alpha receptor, Agonist]

CAS RN

54276-21-0

Alternative/old CAS RN

40665-92-7

EC number

255-028-8

CIPAC number

US EPA chemical code

PubChem CID

5311053

Therapeutic Class

Genito urinary system & sex hormones: Prostaglandins

ATCvet Code

QG02AD90

Controlled Drug?

Regulation 37/2010 MRL Classification

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

Molecular mass

424.9

PIN (Preferred Identification Name)

IUPAC name

(Z)-7-[(1R,2R,3R,5S)-2-[(E,3R)-4-(3-chlorophenoxy)-3-hydroxybut-1-enyl]-3,5-dihydroxycyclopentyl]hept-5-enoic acid

CAS name

Forever chemical

Other status information

Relevant Environmental Water Quality Standards

Physical state

White amorphous, hygroscopic powder

Related substances & organisms

cloprostenol sodium

d-cloprostenol

Commercial

Property

Value

Availability status

Current

Introduction & key dates

1970s, first synthesised; 1980s, initial vet use; 2008, approvals UK

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

Vetoquinol UK Ltd
FATRO S.p.A.
Zoetis UK Ltd
MSD Animal Health UK Ltd

Example products using this active

Bioestrovet Solution for Injection
Dalmazin Solution for Injection
Juramate Solution for Injection
Planate Solution for injection

Formulation and application details

Usually supplied as solution for injection

Commercial production

Cloprostenol is produced through a complex chemical synthesis that builds on the structural framework of prostaglandin F2alpha, its natural analogue. The process typically follows a modified Corey synthesis route, which involves constructing the cyclopentane ring and attaching the appropriate unsaturated side chains with precise stereochemistry. Key steps include alkylation of cyclopentadiene, oxidation, and stereoselective functional group additions to ensure the correct configuration at multiple chiral centres. One of the challenges in production is controlling double bond isomerism, as the molecule contains several conjugated double bonds that can easily isomerise under reaction conditions. The final compound is often converted to its sodium salt form for improved stability and solubility.

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)

50000

Ethanol

60000

DMSO

130000

Dimethylformamide

Melting point (°C)

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

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

Log P

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

Max: 220nm, 275nm, 282nm

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)

Rat

High

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)

High (class III)

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

Rat

High

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

May be absorbed through the skin

Mammalian dose elimination route and rate

Eliminated in approximately equal amounts via the kidney and in bile. Excretion in urine is partly as unchanged parent and partly as metabolites.

Health issues

Specific human health issues (hazard-based)

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

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 sensitiser
May cause vomiting and nausea

Handling issues

Property

Value and interpretation

General

No information available

CLP classification 2013

WHO Classification

Not listed (Not listed)

UN Number

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

cloprostenol

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Polish

Swedish

Hungarian

Dutch

Norwegian

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