Amoxicillin

Amoxicillin	Last updated: 05/09/2025
(Also known as: amoxycillin; amopen; amoxycillin trihydrate; p-hydroxyampicillin; AMC)

GENERAL INFORMATION

Description

A broad spectrum semisynthetic a beta-lactam antibiotic / antimicrobial with applications in veterinary medicine

Examples of veterinary uses

Mainly used to treat skin, respiratory, and urinary tract infections.

Examples of species treated

Birds; Domestic fowl; Cats; Dogs; Pigs

Approval status

VMR 2013/2033 approval status (GB/UK)

Approved - usually available as a prescription only medicine to be authorised by a veterinarian (POM-V)

EU Regulatory approval status

Approved

Chemical structure

Isomerism

Amoxicillin exhibits stereoisomerism, specifically diastereomerism and optical isomerism, due to the presence of multiple chiral centres in its molecular structure. The key chiral centres are located at the 2nd, 5th, and 6th carbon atoms of the penam ring system, which is a fused beta-lactam and thiazolidine ring. These centres give rise to different spatial arrangements of atoms, resulting in stereoisomers that can have distinct biological activities. The clinically active form of amoxicillin is the (2S,5R,6R) isomer, which ensures optimal interaction with bacterial enzymes like transpeptidases.

Chemical formula

C₁₆H₁₉N₃O₅S

Canonical SMILES

CC1(C(N2C(S1)C(C2=O)NC(=O)C(C3=CC=C(C=C3)O)N)C(=O)O)C

Isomeric SMILES

CC1([C@@H](N2[C@H](S1)[C@@H](C2=O)NC(=O)[C@@H](C3=CC=C(C=C3)O)N)C(=O)O)C

International Chemical Identifier key (InChIKey)

LSQZJLSUYDQPKJ-NJBDSQKTSA-N

International Chemical Identifier (InChI)

InChI=1S/C16H19N3O5S/c1-16(2)11(15(23)24)19-13(22)10(14(19)25-16)18-12(21)9(17)7-3-5-8(20)6-4-7/h3-6,9-11,14,20H,17H2,1-2H3,(H,18,21)(H,23,24)/t9-,10-,11+,14-/m1/s1

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
Sodium salt	Variant

General status

Veterinary substance type

Antibacterial, Antibiotic, Medicinal drug

Substance groups

Penicillin related substance

Minimum active substance purity

Known relevant impurities

Substance origin

Semi-synthetic

Mode of action

Inhibits the synthesis of bacterial cell walls

Molecular targets

[Penicillin-binding proteins 1A/1B, Antagonist]

CAS RN

26787-78-0

EC number

248-003-8

CIPAC number

US EPA chemical code

PubChem CID

33613

Therapeutic Class

Antiinfectants for systemic use: Antibacterials for systemic use; Genito urinary system & sex hormones: Antiinfectants & antiseptics for intrautarine use

ATCvet Code

QJ01CR02; QG51AX01

Controlled Drug?

Regulation 37/2010 MRL Classification

Allowed substance (Table 1: All food producing species)

Molecular mass

365.40

PIN (Preferred Identification Name)

IUPAC name

(2S,5R,6R)- 6-([(2R)-2-amino-2-(4-hydroxyphenyl)-acetyl]amino)-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid

CAS name

D-(-)-6-(2-amino-2-phenylacetamido)-3,3-dimethyl-7 -oxo-4-thia-1-azabicyclo [3.2.0] heptane-2-carboxylic acid

Forever chemical

Other status information

Relevant Environmental Water Quality Standards

Physical state

White crystalline solid

Commercial

Property

Product

Manufacturer

Authorisation Route

Legal Class (GB/UK)

Availability status

Current

Introduction & key dates

1958, discovered; 1972, first medical use

Example products (past and present) using this active

Amoxicure 30% powder for oral solution

Oropharma N.V.

UK National authorisation

Prescription only medicine to be authorised by a veterinarian (POM-V)

Amoxypen Suspension for injection

MSD Animal Health UK Ltd

UK National authorisation

Prescription only medicine to be authorised by a veterinarian (POM-V)

Cladaxxa Chewable tablets

Zoetis UK Ltd

UK National authorisation

Prescription only medicine to be authorised by a veterinarian (POM-V)

Betamox suspension for injection

Norbook Labs Ltd

UK National authorisation

Prescription only medicine to be authorised by a veterinarian (POM-V)

Formulation and application details

Usually formulated as tablets or soluble powders to add to drinking water or feed

Commercial production

The production of amoxicillin typically begins with the fermentation of Penicillium chrysogenum to produce penicillin G, which serves as the precursor. This compound is then enzymatically converted into 6-aminopenicillanic acid (6-APA), a key intermediate, using penicillin acylase, a process that marked one of the earliest industrial applications of isolated enzymes. Next, 6-APA undergoes a chemical acylation reaction with p-hydroxyphenylglycine to form amoxicillin. The resulting crude product is purified through crystallisation and filtration to remove impurities and achieve pharmaceutical-grade quality. Modern production often incorporates biocatalysis and synthetic biology to improve yield, selectivity, and environmental sustainability.

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, some broad estimates suggest that typically emissions are likely to be below 5 kg CO₂e/kg of substance.

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

4000

High

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

7500

Methanol

3400

Ethanol

Melting point (°C)

202.7

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

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

7.41 X 10⁰⁰

Calculated

Log P

0.87

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.401

Dissociation constant pKa) at 25 °C

Vapour pressure at 20 °C (mPa)

1.58 X 10^-13

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 ethanol: 230nm = 10850, 274nm = 1400
In acid: 229nm = 9500, 272nm = 1080

Surface tension (mN m⁻¹)

Refractive Index

Environmental release

Substance may enter the environment via the urine of treated animals or by spilt product

Degradation

Property

Value

Source; quality score; and other information

Interpretation

Soil degradation (days) (aerobic)

DT₅₀ (typical)

1.74

Non-persistent

DT₅₀ (lab at 20 °C)

DT₅₀ (field)

DT₉₀ (lab at 20 °C)

DT₉₀ (field)

Note

General literature gives DT₅₀ 0.16-0.29 days, very rapid; ECHA data 1.74 days

Manure DT₅₀ (days)

Manure

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)

Slightly mobile

K_oc (mL g⁻¹)

866

Notes and range

Other data: EPI Suite 108.4 L/kg

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

0.26

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)

> 15000

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)

> 300

Oncorhynchus mykiss

Low

Temperate Freshwater Fish - Chronic 21 day NOEC (mg l⁻¹)

Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

132.4

Danio rerio Embryo 2 day

Low

Temperate Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)

101.6

Daphnia magna

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) (LOEC)

> 1000

Lemna gibba

Low

Aquatic plants (rooted, growth rate, fresh) - 14 day (mg l⁻¹)

Algae - Acute (growth rate, fresh; mg l⁻¹) (EC₅₀)

0.037

Microcystis aeruginosa

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)

> 15000

Rat

Low

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

Mammals - Inhalation LC₅₀ (mg l⁻¹)

Other Mammal toxicity endpoints

Intraperitoneal LD₅₀ = 2870 mg kg⁻¹

rat

Subcutaneous LD₅₀ > 8000 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

Rapidly absorbed by the gastrointestinal tract after oral administration, whilst some is metabolised, it is rapidly mostly unchanged in the urine

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

May cause vomiting, rashes and antibiotic-associated colitis
May cause allergic or asthmatic symptoms or breathing difficulties if inhaled

Handling issues

Property

Value and interpretation

General

Not regulated under IMDG

CLP classification 2013

Health: H317, H334

WHO Classification

Not listed (Not listed)

UN Number

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

amoxicillin

French

amoxicilline

German

Danish

Italian

Spanish

amoxicilina

Greek

Polish

Swedish

Hungarian

Dutch

Norwegian

Record last updated:	05/09/2025
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