Tetracaine
Amethocaine hydrochloride
Also known as: Minims Amethocaine · Tetracaine hydrochloride
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Local anaesthesia of the ocular surface | 1 drop per eye | topical | single application | single dose | 🌍 EU |
- Local anaesthesia of the ocular surface: Uncommonly used; proxymetacaine is advised as an alternative.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Local anaesthesia of the ocular surface | 1 drop per eye | topical | single application | single dose | 🌍 EU |
- Local anaesthesia of the ocular surface: Uncommonly used; proxymetacaine is advised as an alternative.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Tetracaine (also known as amethocaine) is a topical local anaesthetic used primarily for the desensitization of the ocular surface (cornea and conjunctival sac).
Clinical Pearl: Although effective, it is uncommonly used in small animal practice because it tends to cause more marked conjunctival irritation and pain on application compared to alternatives like proxymetacaine. It must never be dispensed for ongoing therapeutic use due to severe corneal toxicity.
Mechanism of action
Local anaesthetic action is dependent on the reversible blockade of the voltage-gated sodium channels → prevents the influx of sodium → inhibits the propagation of an action potential along the nerve fibre. Sensory nerve fibres are blocked before motor nerve fibres, allowing a selective sensory blockade at low doses.
Safety & warnings
Contraindications
- Therapeutic use (repeated administration for pain relief)
- Application prior to a Schirmer tear test
Adverse effects
- Marked conjunctival irritation
- Chemosis
- Pain on application
- Corneal epithelial toxicity
- Delayed healing of corneal ulcers
Precautions
Diagnostic Interference: Topical anaesthetics block reflex tear production and should not be applied before a Schirmer tear test.
Corneal Toxicity: All topical anaesthetics are toxic to the corneal epithelium. Repeated administration can severely delay the healing of ulcers and lead to corneal melting.
Monitoring
- Corneal integrity (fluorescein staining if corneal damage is suspected)
Pharmacokinetics
Absorption
Rapidly absorbed through the conjunctiva and cornea.
Distribution
Local distribution to ocular tissues.
Metabolism
Hydrolyzed by plasma esterases.
Elimination
Metabolites excreted primarily via the kidneys.
Overdose
Overdosage in a clinical setting typically presents as local toxicity rather than systemic effects. Repeated administration leads to severe corneal epithelial toxicity, delayed healing of corneal ulcers, and potential corneal melting.
Do not use for therapeutic purposes.
Available products
Formulations
- Ophthalmic solution: 0.5% (single-use vials)
- Ophthalmic solution: 1% (single-use vials)
Human-labeled
- Minims Amethocaine Hydrochloride 0.5% eye drops
- Minims Amethocaine Hydrochloride 1% eye drops
Regulatory status
Human approved products used off-label in veterinary medicine.
POM (Prescription Only Medicine)
POM (Prescription Only Medicine)
No regulatory data for: 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store according to manufacturer instructions. Unlike proxymetacaine, refrigeration is not required for tetracaine.
Client information
Tetracaine is a fast-acting numbing drop used by your veterinarian to examine your pet's eyes or perform minor procedures.
- Not for home use: This medication is never prescribed for pain relief at home. Repeated use can cause severe, irreversible damage to the surface of the eye (cornea) and prevent normal healing.
- Your pet may experience brief stinging, squinting, or redness immediately after the drops are applied.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.