Gabapentin

Gabapentin	Last updated: 10/09/2025
(Not known by any other names)

GENERAL INFORMATION

Description

Gabapentin is an anticonvulsant drug used for both human and animal patients

Examples of veterinary uses

Once used to treat epilepsy and neuropathic pain but was also used to treat anxietym and fear associated with vet visits

Examples of species treated

Cats; Dogs

Approval status

VMR 2013/2033 approval status (GB/UK)

Not approved

EU Regulatory approval status

Not approved

Chemical structure

Isomerism

Gabapentin exhibits conformational isomerism, rather than classical stereoisomerism. Its structure includes a cyclohexane ring, which can adopt different chair conformations, leading to axial and equatorial forms of the molecule. These conformers differ in the spatial orientation of functional groups, which can influence intramolecular hydrogen bonding and receptor interactions. Recent studies have identified five stable conformers of gabapentin in the gas phase, each with distinct intramolecular interactions between the OH, NH₂, and COOH groups. These conformers are interconvertible and do not represent distinct stereoisomers, but their relative abundance and stability can affect pharmacological behaviour. Additionally, gabapentin exists as a zwitterion at physiological pH, which adds another layer of complexity to its conformational landscape.

Chemical formula

C₉H₁₇NO₂

Canonical SMILES

C1CCC(CC1)(CC(=O)O)CN

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

UGJMXCAKCUNAIE-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C9H17NO2/c10-7-9(6-8(11)12)4-2-1-3-5-9/h1-7,10H2,(H,11,12)

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
gabapentin	-

General status

Veterinary substance type

Medicinal drug: Anticonvulsant & Pain Reliever

Substance groups

Gamma amino-acid

Minimum active substance purity

Known relevant impurities

Substance origin

Synthetic

Mode of action

Gabapentin interacts with cortical neurons at auxillary subunits of voltage-sensitive calcium channels

Molecular targets

[Voltage-dependent calcium channel subunit alpha-2/delta-1, Inhibitor], [Voltage-dependent calcium channel subunit alpha-2/delta-2, Inhibitor], [Voltage-dependent N-type calcium channel subunit alpha-1B , Inhibitor], [Adenosine receptor A1 , Agonist], [NMDA receptor, Unknown action]

CAS RN

60142-96-3

EC number

262-076-3

CIPAC number

US EPA chemical code

PubChem CID

Therapeutic Class

Antiepileptics: Other antiepileptics

ATCvet Code

QN03AX12

Controlled Drug?

UK: Class C, Schedule 3

Regulation 37/2010 MRL Classification

Molecular mass

171.24

PIN (Preferred Identification Name)

1-(aminomethyl)cyclohexaneacetic acid

IUPAC name

1-(aminomethyl)cyclohexaneacetic acid

CAS name

1-(aminomethyl)cyclohexaneacetic acid

Forever chemical

Other status information

Relevant Environmental Water Quality Standards

Physical state

White to off-white crystalline solid

Commercial

Property

Value

Availability status

Current

Introduction & key dates

1980s, developed; 1993, first medical approval USA

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

Pfizer Animal Health

Example products using this active

Neurontin

Formulation and application details

Supplied as liquid suspensions and compounded chewables, human drugs are often used off-label

Commercial production

Gabapentin is produced through a multi-step chemical synthesis that typically begins with 1,1-cyclohexane diacetic anhydride, a key intermediate. This compound undergoes amination reactions with ammonia or amine derivatives to form monoamide or diamide intermediates, which are then transformed into gabapentin’s core structure. One widely used industrial method involves a Hofmann rearrangement, where a cyclic amide is converted into an isocyanate, followed by hydrolysis to yield gabapentin hydrochloride. The final step involves ion exchange purification to isolate gabapentin in its free base form.

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)

4500

High

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

Melting point (°C)

162

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

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

7.94 X 10^-02

Calculated

Log P

-1.1

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

Dissociation constant pKa) at 25 °C

3.68

pKa(2)=10.70

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

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)

> 8053

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)

Danio rerio as mM

Low

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)

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)

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 8053

Rat

Low

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

Mammals - Inhalation LC₅₀ (mg l⁻¹)

Other Mammal toxicity endpoints

Intravenous LD₅₀ > 1000 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

Renal excretion as unchanged drug

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, drowsiness, loss of balance and/or diarrhoea
May cause calcium, vitamin D, vitamin B1 & folate deficiencies

Handling issues

Property

Value and interpretation

General

Will emit toxic gases when heated to decomposition

CLP classification 2013

Health: H315, H319, H360, H335

WHO Classification

Not listed (Not listed)

UN Number

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

gabapentin

French

gabapentine

German

Danish

Italian

gabapentino

Spanish

gabapentina

Greek

Polish

Swedish

Hungarian

Dutch

Norwegian

Record last updated:	10/09/2025
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