Halofuginone hydrobromide

Halofuginone hydrobromide	Last updated: 15/09/2025
(Also known as: halofuginone HBr)

GENERAL INFORMATION

Description

A quinazoline anti-coccidial drug with veterinary applications. The active substance was originally obtained by modification of a substance isolated from Dichroa febrifuqa

Examples of veterinary uses

Used for the prevention of diarrhoea due to diagnosed Cryptosporidium parvum

Examples of species treated

Poultry; Cattle (calves)

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

Halofuginone hydrobromide exhibits stereoisomerism due to the presence of two chiral centres located on its piperidine ring, specifically at the 2nd and 3rd carbon atoms. These centres give rise to distinct stereoisomers, but the biologically active form used in veterinary and pharmaceutical applications is the (2R,3S)-isomer.

Chemical formula

C₁₆H₁₈Br₂ClN₃O₃

Canonical SMILES

C1CC(C(NC1)CC(=O)CN2C=NC3=CC(=C(C=C3C2=O)Cl)Br)O.Br

Isomeric SMILES

C1C[C@@H]([C@H](NC1)CC(=O)CN2C=NC3=CC(=C(C=C3C2=O)Cl)Br)O.Br

International Chemical Identifier key (InChIKey)

SJUWEPZBTXEUMU-LIOBNPLQSA-N

International Chemical Identifier (InChI)

InChI=1S/C16H17BrClN3O3.BrH/c17-11-6-13-10(5-12(11)18)16(24)21(8-20-13)7-9(22)4-14-15(23)2-1-3-19-14;/h5-6,8,14-15,19,23H,1-4,7H2;1H/t14-,15+;/m1./s1

2D structure diagram/image available?

Yes

General status

Veterinary substance type

Coccidiostat, Antiprotozoal, Feed additive

Substance groups

Quinazolinone

Minimum active substance purity

Known relevant impurities

Substance origin

Semi-synthetic

Mode of action

Inhibits the development of T helper 17 cells that influence immune function

Molecular targets

[Growth factor - Beta (TGF-Beta), Inhibitor]

CAS RN

64924-67-0

Alternative/old CAS RN

57426-42-3

EC number

694-602-6

CIPAC number

US EPA chemical code

PubChem CID

11591339

Therapeutic Class

Antiparasitic products, insecticides & repellents: Antiprotozoals

ATCvet Code

QP51AX08

Controlled Drug?

Regulation 37/2010 MRL Classification

Allowed substance (Table 1: Bovine)

Molecular mass

495.6

PIN (Preferred Identification Name)

IUPAC name

7-bromo-6-chloro-3-[3-[(2R,3S)-3-hydroxypiperidin-2-yl]-2-oxopropyl]quinazolin-4-one; hydrobromide

CAS name

Forever chemical

Other status information

Relevant Environmental Water Quality Standards

Physical state

Yellow liquid

Related substances & organisms

halofuginone lactate

halofuginone

Commercial

Property

Value

Availability status

Current

Introduction & key dates

Early 1980s, introduced; 1986, registered USA

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

Livzon Group Fuzhou Fuxing Pharmaceutical Co. China
ATK Chemical Co. Ltd.

Example products using this active

Halocur

Formulation and application details

Usually supplied as an oral solution

Commercial production

The commercial production of halofuginone hydrobromide begins with the synthesis of a key intermediate, 7-bromo-6-chloroquinazolin-4(3H)-one, typically derived from m-chlorotoluene through conventional halogenation and cyclisation steps. This intermediate is then reacted with chloroacetone to introduce a side chain, forming 7-bromo-6-chloro-3-(3-chloroacetonyl)quinazolinone. The compound undergoes a multi-step transformation involving condensation, cyclisation, deprotection, and stereoselective isomerisation to yield the active (2R,3S)-halofuginone structure. Finally, the product is treated with hydrobromic acid to form the hydrobromide salt.

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)

3.0

Low

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

Melting point (°C)

294

Boiling point (°C)

Degradation point (°C)

294

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

Maxima at 243nm, 275nm, 300nm, 313nm & 326nm

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)

Moderately persistent

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)

34.7

Slightly mobile

K_oc (mL g⁻¹)

3855

Notes and range

USEPA data: K_d range 22-51.8 mL g⁻¹, K_oc range 1515-3855 mL g⁻¹, Soils=3

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

0.68

Calculated

Low leachability

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)

F4 Mouse, as halofuginone 4.4

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)

17.6

Gallus gallus domesticus as halofuginone

High

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)

> 21.0

Lumbricus terrestris NOEL lactate salt

Moderate

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)

0.12

Lepomis macrochirus as halofuginone

Moderate

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)

0.02

Daphnia magna as halofuginone

High

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)

F4 Mouse, as halofuginone 4.4

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

Mammalian dose elimination route and rate

Around 80% of dose is eliminated in faeces within a week. Some residues also identified in bile.

Health issues

Specific human health issues (hazard-based)

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

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 and kideny toxicant

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

halofuginone hydrobromide

French

German

Danish

Italian

Spanish

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