Lasalocid sodium

Lasalocid sodium	Last updated: 15/09/2025
(Also known as: lasalocid A)

GENERAL INFORMATION

Description

A divalent polyether ionophore antibiotic and antiparasitic veterinary drug used to control gram-positive bacteria

Examples of veterinary uses

Used as a feed supplement for fattening game birds and cattle; Also used for the prevention of coccidiosis caused by Eimeria spp. in game birds.

Examples of species treated

Turkeys; Chickens; Game birds; Sheep; Cattle

Approval status

VMR 2013/2033 approval status (GB/UK)

Not approved

EU Regulatory approval status

Not approved

Chemical structure

Isomerism

Lasalocid sodium exhibits stereoisomerism, specifically diastereomerism, due to its complex polyether structure with multiple chiral centres. The molecule contains several cyclic ether rings and hydroxyl groups arranged in a rigid three-dimensional framework, which allows for different spatial configurations of atoms without altering the molecular formula. One notable isomer, sometimes referred to as iso-lasalocid A, differs from the standard lasalocid A in the size and absolute configuration of its terminal cyclic ether, leading to distinct physical properties. These isomers arise naturally during biosynthesis by Streptomyces lasaliensis, and their formation is influenced by the cyclisation mechanisms of the polyether backbone.

Chemical formula

C₃₄H₅₃O₈Na

Canonical SMILES

CCC(C1C(CC(O1)(CC)C2CCC(C(O2)C)(CC)O)C)C(=O)C(C)C(C(C)CCC3=C(C(=C(C=C3)C)O)C(=O)[O-])O.[Na+]

Isomeric SMILES

CC[C@H]([C@@H]1[C@H](C[C@@](O1)(CC)[C@H]2CC[C@@]([C@@H](O2)C)(CC)O)C)C(=O)[C@@H](C)[C@H]([C@H](C)CCC3=C(C(=C(C=C3)C)O)C(=O)[O-])O.[Na+]

International Chemical Identifier key (InChIKey)

RDHDUYAKDYQPEW-HWLWSTNVSA-M

International Chemical Identifier (InChI)

InChI=1S/C34H54O8.Na/c1-9-25(31-21(6)18-34(11-3,42-31)26-16-17-33(40,10-2)23(8)41-26)30(37)22(7)28(35)19(4)12-14-24-15-13-20(5)29(36)27(24)32(38)39;/h13,15,19,21-23,25-26,28,31,35-36,40H,9-12,14,16-18H2,1-8H3,(H,38,39);/q;+1/p-1

2D structure diagram/image available?

Yes

General status

Veterinary substance type

Antibiotic, Medicinal drug, Feed additive, Coccidiostat, Antiparasitic

Substance groups

Ionophore

Minimum active substance purity

97%

Known relevant impurities

Substance origin

Synthetic

Mode of action

Dissociates the calcium fluxes in muscle fibres. Lasalocid sodium disturbs ionic homeostasis, leading to osmotic lysis of coccidia.

Molecular targets

[Ionic homeostasis, Antagonist]

CAS RN

25999-20-6

EC number

247-400-3

CIPAC number

US EPA chemical code

PubChem CID

Therapeutic Class

Antiparasitic products, insecticides & repellents: Antiprotozoals

ATCvet Code

QP51AH02

Controlled Drug?

Regulation 37/2010 MRL Classification

Allowed substance (Table 1: Poultry)

Molecular mass

612.77

PIN (Preferred Identification Name)

IUPAC name

(2R-(2α(2S*(3R*,4S*,5S*,7R*),3S*,5S*),5α,6β))-6-(7-(5-Ethyl-5-(5-ethyltetrahydro-5-hydroxy-6-methyl-2H-pyran-2-yl)tetrahydro-3-methyl-2-furanyl)-4-hydroxy-3,5-dimethyl-6-oxononyl)-2-hydroxy-3-methylbenzoic acid monosodium salt

CAS name

Benzoic acid, 6-(3R,4S,5S,7R)-7-(2S,3S,5S)-5-ethyl-5-(2R,5R,6S)-5-ethyltetrahydro-5-hydroxy-6-methyl-2H-pyran-2-yltetrahydro-3-methyl-2-furanyl-4-hydroxy-3,5-dimethyl-6-oxononyl-2-hydroxy-3-methyl-, monosodium salt

Forever chemical

Other status information

Relevant Environmental Water Quality Standards

Physical state

White to brown coloured powder

Commercial

Property

Value

Availability status

Introduction & key dates

1951, first reported

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

Alpharma Animal Health BVBA
Alpharma Animal Health Pty Ltd

Example products using this active

Avatec Premix Medicated Feed
Bovatec Premix

Formulation and application details

Usually formulated as a medicated feed or feed additive

Commercial production

Lasalocid sodium is produced through microbial fermentation using the actinomycete Streptomyces lasaliensis, which naturally synthesizes this polyether ionophore antibiotic. The process begins by cultivating the microorganism in a carefully optimised nutrient medium under controlled conditions of temperature, pH, and aeration. During fermentation, lasalocid is secreted into the broth as a secondary metabolite. After sufficient incubation, the culture is harvested and subjected to extraction and purification steps, typically involving solvent extraction, filtration, and chromatographic techniques, to isolate lasalocid in its sodium salt form.

Impact on climate of production and use

As microbial-based products tend to use fermentation-based production processes rather than chemical synthesis, they typically have a lower fossil fuel input in formulation and active ingredient creation, and also have reduced downstream emissions due to biodegradability and minimal soil disruption, their life-cycle GHG emissions are expected to be low. Whilst hard and precise data is not available, broad estimates suggest that typically emissions are likely to be below 5 kg CO₂e/kg.

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)

10000

Methanol

Melting point (°C)

180

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

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

1.00 X 10²²⁵5

Calculated

Log P

225

High

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.119

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

Substance may enter the environment via the faeces of treated animals or by leaching from spilt medicated feed.

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)

323

Notes and range

K_oc value is for the acid

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)

122

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)

> 59

Gallus domesticus

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)

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)

3.0

Oncorhynchus mykiss

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)

3.6

Daphnia magna

Moderate

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) (EC₅₀)

2.4

Desmodesmus subspicatus

Moderate

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)

122

Rat

Moderate

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

1400

Rabbit

Mammals - Inhalation LC₅₀ (mg l⁻¹)

Other Mammal toxicity endpoints

Intraperitoneal LD₅₀ = 64 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

Widespread distribution throughout the body once administered. Blood elimination DT50 is ~3hrs in rats. Almost totally excreted by the biliary duct.

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

No data found

Eye irritant

Phototoxicant

No data found

General human health issues

Toxic to humans, horses and other species - has low margin of safety
Poison by ingestion and intraperitoneal routes

Handling issues

Property

Value and interpretation

General

When heated to decomposition it emits acrid smoke and irritating fumes
IMDG Transport Hazard Class 6.1(b)

CLP classification 2013

WHO Classification

Not listed (Not listed)

UN Number

UN2811

Waste disposal & packaging

Packaging Group III (minor danger)

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

lasalocid sodium

French

lasalocide sodique

German

Danish

Italian

Spanish

lasalocido sodico

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