Ampicillin

Ampicillin	Last updated: 07/09/2025
(Also known as: alpha-aminobenzylpenicillin)

GENERAL INFORMATION

Description

A common and extensively used antibiotic for a broad range of both gram-positive and gram-negative bacterial infections

Examples of veterinary uses

Used to treat upper respiratory infections like pneumonia, urinary tract infections, skin infections, soft tissue infections, gastroenteritis, tonsillitis, salmonella, canine parvovirosis, and leptospirosis

Examples of species treated

Dogs; Cats; Rabbits; Cattle; Sheep; 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

Ampicillin exhibits stereoisomerism, specifically optical isomerism, due to the presence of a chiral centre in its beta-lactam ring structure. The molecule contains an asymmetric carbon atom at the 6-position of the penicillin nucleus, which allows for the existence of enantiomers. However, only the (−)-6R-isomer of ampicillin is biologically active and used therapeutically, as it fits properly into bacterial penicillin-binding proteins to inhibit cell wall synthesis. The inactive enantiomer lacks this precise fit and is therefore not effective.

Chemical formula

C₁₆H₁₉N₃O₄S

Canonical SMILES

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

Isomeric SMILES

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

International Chemical Identifier key (InChIKey)

AVKUERGKIZMTKX-NJBDSQKTSA-N

International Chemical Identifier (InChI)

InChI=1S/C16H19N3O4S/c1-16(2)11(15(22)23)19-13(21)10(14(19)24-16)18-12(20)9(17)8-6-4-3-5-7-8/h3-7,9-11,14H,17H2,1-2H3,(H,18,20)(H,22,23)/t9-,10-,11+,14-/m1/s1

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
ampicillin	-

General status

Veterinary substance type

Antibacterial, Antibiotic

Substance groups

Aminopenicillin

Minimum active substance purity

Known relevant impurities

During degradation or synthesis, diastereomeric impurities can form

Substance origin

Semi-synthetic

Mode of action

Broad-spectrum, inhibts bacterial cell-wall synthesis

Molecular targets

[Penicillin-binding protein 2a, Antagonist], [Penicillin-binding protein 1b, Antagonist], [Penicillin-binding protein 3, Antagonist], [Penicillin-binding protein 1A, Antagonist], [Penicillin-binding protein 2B, Antagonist]

CAS RN

69-53-4

EC number

200-709-7

CIPAC number

US EPA chemical code

PubChem CID

6249

Therapeutic Class

Antiinfectants for systemic use: Antibacterials for intramammary

ATCvet Code

QJ51CA01

Controlled Drug?

Regulation 37/2010 MRL Classification

Allowed substance (Table 1: All food producing species)

Molecular mass

349.41

PIN (Preferred Identification Name)

IUPAC name

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

CAS name

6-(D(-)-α-aminophenylacetamido)penicillanic acid

Forever chemical

Other status information

Relevant Environmental Water Quality Standards

Physical state

White to off-white powder

Commercial

Property

Product

Manufacturer

Authorisation Route

Legal Class (GB/UK)

Availability status

Current

Introduction & key dates

1958, first synthesised; 1961, introduced commercially; 1971, pivampicillin, a prodrug of ampicillin launched

Example products (past and present) using this active

Amfipen LA, 100 mg/ml suspension for injection

MSD Animal Health UK Ltd

UK National authorisation (IC)

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

Bovaclox DC Xtra Intramammary Suspension

Norbrook Laboratories Ltd

UK National authorisation

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

Lactaclox Intramammary Infusion

Norbrook Laboratories Ltd

UK National authorisation

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

Kloxerate Gold Intrammary Infusion

Zoetis UK Ltd

UK National authorisation (IC)

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

Formulation and application details

Supplied in a variety of formulations including intramammary suspensions & infustions, capsules and solutions for injection

Commercial production

Ampicillin is produced through a semi-synthetic process that begins with the fermentation of Penicillium chrysogenum, a fungus that naturally produces penicillin G. This base compound is extracted and purified, then chemically modified to introduce an amino group, transforming it into ampicillin and broadening its antibacterial spectrum. The chemical synthesis involves acylation of 6-aminopenicillanic acid (6-APA), the core structure of penicillin, with D-phenylglycine to form the ampicillin molecule.

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. However, the semi-synthetic nature of the production process for this substance is likely to increase emissions.

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

10100

High

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

50000

Methanol

4000

Ethanol

77000

Dimethylacetamide

Melting point (°C)

208

Boiling point (°C)

Degradation point (°C)

200

Flashpoint (°C)

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

7.41 X 10^-02

Calculated

Log P

-1.13

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

Dissociation constant pKa) at 25 °C

2.61

Vapour pressure at 20 °C (mPa)

1.61 X 10^-14

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

5R,6R-penicilloic acid

Animal (Urine)

5S,6R-penicilloic acid

Animal (Urine)

piperazine-2,5-dione

Animal (Urine)

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 5000

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)

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)

> 1000

Raphidocelis subcapitata

Low

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

> 1000

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)

> 5000

Rat

Low

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

Mammals - Inhalation LC₅₀ (mg l⁻¹)

Other Mammal toxicity endpoints

Subcutaneous LD₅₀ > 5000 mg kg⁻¹

Rat

Intraperitoneal LD₅₀ = 4500 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, largely unchanged, in the urine and to a lesser extent in faeces and bile

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

May induce asthma, diarrhoea, nausea, vomiting, epigastric and abdominal pain
May cause skin rashes and sensitisation

Handling issues

Property

Value and interpretation

General

No information available

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

ampicillin

French

ampicilline

German

Danish

Italian

Spanish

ampicilina

Greek

Polish

Swedish

Hungarian

Dutch

Norwegian

Record last updated:	07/09/2025
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