Dirlotapide

Dirlotapide	Last updated: 16/09/2025
(Not known by any other names)

GENERAL INFORMATION

Description

A veterinary antiobesity drug

Examples of veterinary uses

Used to manage obesity in dogs by reducing appetite

Examples of species treated

Dogs

Approval status

VMR 2013/2033 approval status (GB/UK)

Not approved

EU Regulatory approval status

Not approved

Chemical structure

Isomerism

Dirlotapide exhibits stereoisomerism, specifically chirality, due to the presence of a chiral centre in its molecular structure. The molecule contains a stereogenic carbon atom at the phenylethyl moiety. It is usually formulated for veterinary use as the (1S)-enantiomer.

Chemical formula

C₄₀H₃₃F₃N₄O₃

Canonical SMILES

CN1C2=C(C=C(C=C2)NC(=O)C3=CC=CC=C3C4=CC=C(C=C4)C(F)(F)F)C=C1C(=O)NC(C5=CC=CC=C5)C(=O)N(C)CC6=CC=CC=C6

Isomeric SMILES

CN1C2=C(C=C(C=C2)NC(=O)C3=CC=CC=C3C4=CC=C(C=C4)C(F)(F)F)C=C1C(=O)N[C@H](C5=CC=CC=C5)C(=O)N(C)CC6=CC=CC=C6

International Chemical Identifier key (InChIKey)

TUOSYWCFRFNJBS-PSXMRANNSA-N

International Chemical Identifier (InChI)

InChI=1S/C40H33F3N4O3/c1-46(25-26-11-5-3-6-12-26)39(50)36(28-13-7-4-8-14-28)45-38(49)35-24-29-23-31(21-22-34(29)47(35)2)44-37(48)33-16-10-9-15-32(33)27-17-19-30(20-18-27)40(41,42)43/h3-24,36H,25H2,1-2H3,(H,44,48)(H,45,49)/t36-/m1/s1

2D structure diagram/image available?

Yes

General status

Veterinary substance type

Antiobesity drug, Medicinal drug

Substance groups

Unclassified substance

Minimum active substance purity

Known relevant impurities

Substance origin

Synthetic

Mode of action

Acts by blocking the assembly and release of lipoproteins into the bloodstream, thereby reducing fat absorption

Molecular targets

[Microsomal triglyceride transfer protein, Inhibitor]

CAS RN

481658-94-0

EC number

CIPAC number

US EPA chemical code

PubChem CID

Therapeutic Class

Alimentary tract & metabolism: Antiobesity preparations, excluding diet products

ATCvet Code

QA08AB91

Controlled Drug?

Regulation 37/2010 MRL Classification

Molecular mass

674.71

PIN (Preferred Identification Name)

IUPAC name

1-methyl-N-[(1S)-2-(methyl-(phenylmethyl)amino)-2-oxo-1-phenylethyl]-5-[ [oxo-[2-[4-(trifluoromethyl)phenyl]phenyl]methyl]amino]-2-indolecarboxamide

CAS name

Forever chemical

Other status information

Relevant Environmental Water Quality Standards

Physical state

White to beige coloured crystalline solid

Commercial

Property

Value

Availability status

Introduction & key dates

Early 2000s, development; 2006, approval USA; Post-2007, approvals EU; 2010s, withdrawal EU

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

Pfizer Animal Health

Example products using this active

Slentrol Oral Solution

Formulation and application details

Usually administered orally

Commercial production

Dirlotapide is produced through a multi-step organic synthesis that constructs its complex indole-based structure and incorporates key functional groups for its activity as a microsomal triglyceride transfer protein inhibitor. The process begins with the preparation of substituted aromatic intermediates, including fluorinated phenyl and trifluoromethylbenzyl derivatives, which are coupled via amide and urea linkages to form the core scaffold. A crucial step involves the stereoselective introduction of the (1S)-chiral centre, ensuring the correct enantiomer for biological efficacy. The synthesis proceeds through controlled condensation, cyclisation, and purification steps, using conventional equipment and standard pharmaceutical techniques.

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)

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

Melting point (°C)

123

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

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

Log P

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

Dissociation constant pKa) at 25 °C

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)

> 2000

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)

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)

> 2000

Rat

Low

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

2000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

Other Mammal toxicity endpoints

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

Rapid absorption, highly protein bound, elminated predominately in the faeces.

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 gastrointestinal problems

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

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Name

English

dirlotapide

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Swedish

Hungarian

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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