Norfloxacin

Norfloxacin	Last updated: 06/09/2025
(Not known by any other names)

GENERAL INFORMATION

Description

Broad spectrum antiobiotic drug active against both gram-positive and gram-negative bacteria

Examples of veterinary uses

Mainly used to treat urinary tract, respiratory and other infectious diseases

Examples of species treated

Sheep; Pigs; Dogs; Cats

Approval status

VMR 2013/2033 approval status (GB/UK)

Not approved

EU Regulatory approval status

Not approved

Chemical structure

Isomerism

Norfloxacin primarily exhibits polymorphism, a type of isomerism where the same chemical compound can crystallise into different solid forms. These polymorphs, known as Form A, Form B, and Form C, have distinct molecular packing arrangements and physical properties such as solubility, melting point, and stability. Notably, Form B is the most stable at room temperature, while Form A is metastable and can transform into Form B under certain conditions, demonstrating an enantiotropic relationship.

Chemical formula

C₁₆H₁₈FN₃O₃

Canonical SMILES

CCN1C=C(C(=O)C2=CC(=C(C=C21)N3CCNCC3)F)C(=O)O

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

OGJPXUAPXNRGGI-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C16H18FN3O3/c1-2-19-9-11(16(22)23)15(21)10-7-12(17)14(8-13(10)19)20-5-3-18-4-6-20/h7-9,18H,2-6H2,1H3,(H,22,23)

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
norfloxacin	-

General status

Veterinary substance type

Antibiotic, Antibacterial, Chemotherapy drug, Medicinal drug

Substance groups

Fluoroquinolone

Minimum active substance purity

Known relevant impurities

Substance origin

Synthetic

Mode of action

Inhibits bacterial DNA gyrase

Molecular targets

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

CAS RN

70458-96-7

EC number

274-614-4

CIPAC number

US EPA chemical code

PubChem CID

Therapeutic Class

Antiinfectants for systemic use: Antibacterials for systemic use

ATCvet Code

QJ01MA06

Controlled Drug?

Regulation 37/2010 MRL Classification

Molecular mass

319.33

PIN (Preferred Identification Name)

IUPAC name

1-ethyl-6-fluoro-4-oxo-7-piperazin-1-yl-1H-quinoline-3-carboxylic acid

CAS name

1,4-dihydro-1-ethyl-6-fluoro-4-oxo-7-(1-piperazinyl)-3-quinolinecarboxylic acid

Forever chemical

Other status information

Evidence of use in third world countries

Relevant Environmental Water Quality Standards

Physical state

White to pale yellow crystalline powder

Commercial

Property

Product

Manufacturer

Authorisation Route

Legal Class (GB/UK)

Availability status

Introduction & key dates

1979, first patent

Example products (past and present) using this active

Formulation and application details

Commercial production

The production of norfloxacin involves a multi-step synthetic process based around constructing its fluoroquinolone core. It begins with the preparation of key intermediates such as 3,4-difluoroaniline, which is reacted to form 6-fluoro-3,4-dihydro-4-oxoquinoline, a crucial building block. This intermediate undergoes cyclisation to establish the quinolone ring system, followed by the introduction of the piperazine moiety through nucleophilic substitution using piperazine under controlled temperature and pH conditions.

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)

178000

High

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

980

Methanol

1900

Ethanol

5100

Acetone

5500

Chloroform

Melting point (°C)

227

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

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

8.51 X 10⁰⁰

Calculated

Log P

0.93

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

Dissociation constant pKa) at 25 °C

6.26

pKa(2) = 8.75

Vapour pressure at 20 °C (mPa)

9.00 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

In NaOH: 274nm, 325nm, 336nm

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)

> 4000

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)

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)

> 2

Ceriodaphnia dubia LC₅₀

Moderate

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)

16.6

Raphidocelis subcapitata

Low

Algae - Chronic (growth rate, fresh; mg l⁻¹) (NOEC)

4.01

Raphidocelis subcapitata

Low

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)

> 4000

Rat

Low

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

Mammals - Inhalation LC₅₀ (mg l⁻¹)

Other Mammal toxicity endpoints

Subcutaneous LD₅₀ > 1500 mg kg⁻¹

Rat

Intravenous LD₅₀ = 245 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

Eliminated through metabolism, biliary excretion, and renal excretion.

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

Possible kidney, liver and renal toxicant

Handling issues

Property

Value and interpretation

General

Hygroscopic in air

CLP classification 2013

WHO Classification

Not listed (Not listed)

UN Number

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

norfloxacin

French

norfloxacine

German

Danish

Italian

Spanish

norfloxacino

Greek

Polish

Swedish

Hungarian

Dutch

Norwegian

Record last updated:	06/09/2025
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