What is the duration of action of tetracaine?

Duration of Action of Tetracaine

Tetracaine has a duration of action of 30-60 minutes, with effects lasting up to 180-600 minutes in certain applications. 1

Pharmacological Properties of Tetracaine

Tetracaine is a potent ester-type local anesthetic agent with the following characteristics:

• Onset of action:

  • For ophthalmic use: Maximum effect achieved within 10-20 seconds after instillation 2
  • For topical application: 1-5 minutes 1

• Duration of action:

  • Standard duration: 30-60 minutes 1
  • Extended duration: 180-600 minutes (3-10 hours) when used for nerve blocks or infiltration 1
  • Ophthalmic use: 10-20 minutes for single application 2

Factors Affecting Duration

The duration of tetracaine's anesthetic effect can vary based on several factors:

• Formulation: Different formulations can significantly affect duration
• Concentration: Higher concentrations generally provide longer duration
• Site of administration: Highly vascular areas may have shorter duration due to faster absorption
• Use of vasoconstrictors: Addition of epinephrine can extend duration
• Individual patient factors: Age, weight, and metabolism can affect duration

Comparative Duration with Other Local Anesthetics

When compared to other commonly used local anesthetics:

• Tetracaine: 180-600 minutes (longest duration among ester anesthetics) 1
• Lidocaine: 90-200 minutes 1
• Proparacaine: Shorter duration than tetracaine for ophthalmic use 3

Clinical Applications

Ophthalmic Use

For ophthalmic procedures, tetracaine provides:

• Maximum effect within 10-20 seconds
• Duration of 10-20 minutes with a single application
• Duration can be extended with repeated dosing 2
• Demonstrated longer duration of action compared to proparacaine in corneal sensitivity studies 3

Intranasal Application

When used for nasal procedures:

• Provides superior anesthesia compared to lidocaine
• Effects still present at 70 minutes post-application 4

Extended Release Formulations

Microencapsulated tetracaine formulations have been developed to:

• Increase duration of action up to 4-fold (approximately 40-60 minutes)
• Provide immediate onset with extended effect throughout surgical procedures 5

Safety Considerations

When using tetracaine, be aware of:

• Maximum safe dosage: 1-1.5 mg/kg without epinephrine 1
• Potential for corneal toxicity: Prolonged use of topical ocular anesthetic may produce permanent corneal opacification and ulceration 2
• Effect on intraocular pressure: May cause significant reduction in IOP after 15 minutes of application 6

Clinical Pearl

For procedures requiring longer anesthesia, consider:

1. Using tetracaine for its longer duration compared to other ester anesthetics
2. Repeated application to extend the duration (with caution regarding total dose)
3. Alternative anesthetics like bupivacaine (180-600 minutes) if very long duration is needed 1

Tetracaine's duration of action makes it particularly suitable for short to medium-length procedures, with its extended duration in certain applications making it versatile across various clinical settings.