Lomefloxacin hydrochloride

Lomefloxacin hydrochloride	Last updated: 16/09/2025
(Also known as: lomefloxacin HCl)

GENERAL INFORMATION

Description

An antibiotic drug active against both gram-positive and gram-negative bacteria

Examples of veterinary uses

Used to treat bacterial infections particularly those of the respiratory and urinary tracts in poultry

Examples of species treated

Poultry; Horses; Dogs

Approval status

VMR 2013/2033 approval status (GB/UK)

Not approved

EU Regulatory approval status

Not approved

Chemical structure

Isomerism

None

Chemical formula

C₁₇H₂₀F₂N₃O₃Cl

Canonical SMILES

CCN1C=C(C(=O)C2=CC(=C(C(=C21)F)N3CCNC(C3)C)F)C(=O)O.Cl

Isomeric SMILES

International Chemical Identifier key (InChIKey)

KXEBLAPZMOQCKO-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C17H19F2N3O3/c1-3-21-8-11(17(24)25)16(23)10-6-12(18)15(13(19)14(10)21)22-5-4-20-9(2)7-22/h6,8-9,20H,3-5,7H2,1-2H3,(H,24,25)

2D structure diagram/image available?

Yes

General status

Veterinary substance type

Antibiotic, Antibacterial, Medicinal drug

Substance groups

Fluoroquinolone

Minimum active substance purity

Known relevant impurities

Substance origin

Synthetic

Mode of action

Bactericidal action results from interference with the activity of the bacterial enzymes DNA gyrase and topoisomerase IV, which are needed for the transcription and replication of bacterial DNA

Molecular targets

[DNA topoisomerase 4 subunit A, Antagonist], [DNA gyrase subunit A, Antagonist], [DNA topoisomerase 2-alpha, Antagonist]

CAS RN

98079-52-8

EC number

CIPAC number

US EPA chemical code

PubChem CID

Therapeutic Class

Antiinfectants for systemic use: Antibacterials for systemic use; Sensory organs: Ophthalmologicals

ATCvet Code

QJ01MA07; QS01AX17

Controlled Drug?

Regulation 37/2010 MRL Classification

Molecular mass

387.8

PIN (Preferred Identification Name)

IUPAC name

(RS)-1-ethyl-6,8-difluoro-7-(3-methylpiperazin-1-yl)-4-oxo-quinoline-3-carboxylic acid hydrochloride

CAS name

1,4-dihydro-6,8-difluoro-1-ethyl-7-(3-methyl-1-piperazinyl)-4-oxo-3-quinolinecarboxylic acid hydrochloride

Forever chemical

Other status information

Relevant Environmental Water Quality Standards

Physical state

White to pale yellow coloured powder

Related substances & organisms

ciprofloxacin

Commercial

Property

Value

Availability status

Introduction & key dates

1983, patent filed; 1988, first approvals; 2008, FDA health impact warning

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

Henrikang Pharma
Vortex Products UK

Example products using this active

Okacyn
Maxaquin
Lomequin

Formulation and application details

Available as a variety of products including solutions for various ophthalmic and otic applications

Commercial production

The production of lomefloxacin hydrochloride involves a multi-step synthetic process beginning with the coupling of 2,3,4-trifluoroaniline and 2-chloromethylene diethyl malonate. This reaction, conducted at around 50–60 DegC, forms a key intermediate. The next step is a cyclisation reaction at a higher temperature, yielding 6,7,8-trifluoro-1,4-dihydro-4-oxo-3-quinoline carboxylic acid ethyl ester, a core structure of the fluoroquinolone class. This intermediate is then further modified, typically through substitution with piperazine derivatives, to introduce the side chain that enhances antibacterial activity. The final step involves conversion to the hydrochloride salt, which improves solubility and stability for pharmaceutical use.

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)

27200

High

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

Melting point (°C)

240

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

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

9.77 X 10⁰⁰

Calculated

Log P

0.99

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

Dissociation constant pKa) at 25 °C

5.9

Vapour pressure at 20 °C (mPa)

6.28 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

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 soil and groundwater metabolites

None

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

lomefloxacin glucuronide

~9% of administered dose

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 3800

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)

170

Oncorhynchus mykiss as acid

Low

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)

130

Daphnia magna as acid

Low

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)

58.0

Scenedesmus vacuolatus as acid

Low

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)

> 3800

Rat

Low

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

Mammals - Inhalation LC₅₀ (mg l⁻¹)

Other Mammal toxicity endpoints

Subcutaneous LD₅₀ = 995 mg kg⁻¹

Mouse

Intravenous LD₅₀ = 328 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

Excreted mainly via the urine within 72 hours of administration, around 65% of the dose is as the unchanged parent

Health issues

Specific human health issues

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

No data found

Eye irritant

Phototoxicant

General human health issues

Liver toxicant
May cause nausea, vomiting or diarrhoea
May cause sun sensitivity
May cause tendon deterioration

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

lomefloxacin hydrochloride

French

chlorhydrate de lomefloxacine

German

Danish

Italian

Spanish

hidrocloruro de lomefloxacino

Greek

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