Tetracaine
Pontocaine
Ester local anesthetic (long-acting)
Blocks voltage-gated Na⁺ channels. Long-acting ester, metabolized by plasma cholinesterase. High potency + toxicity.
Indications
- •Spinal anesthesia
- •Topical ophthalmic/airway anesthesia
Dosing
| Context | Adult | Pediatric |
|---|---|---|
| Spinal | 5–20 mg (often with dextrose for hyperbaric, or epi/phenylephrine to prolong) | — |
| Topical | Limit total dose — rapid mucosal absorption | — |
Maximum dose
1.5 mg/kg plain (absolute max 20 mg)
Max-dose calculator
single-injection infiltration / blockPlain
20 mg
Capped at absolute max 20 mg
| Concentration | Max volume (plain) |
|---|---|
| 0.5% (5 mg/mL) | 4 mL |
| 1% (10 mg/mL) | 2 mL |
Primarily spinal/topical; topical mucosal absorption is rapid — respect total-dose limits. Education only — confirm against the package insert. Max doses are not additive across agents; account for total LA when mixing.
Pharmacokinetics
Spinal onset 3–5 min, duration 2–3 h (longer with vasoconstrictor). Ester → plasma cholinesterase metabolism → PABA.
Side effects
- !LAST
- !PABA allergy (ester class)
- !Prolonged block
- !Methemoglobinemia (rare)
Contraindications
- ×Ester (PABA) allergy
- ×Plasma cholinesterase deficiency (prolonged effect)
Clinical pearls
- ★Classic hyperbaric spinal agent; vasoconstrictor markedly prolongs it.
- ★Ester → PABA metabolite → higher allergy potential than amides.
Other drugs in Local Anesthetics
- Lidocaine
Blocks voltage-gated Na⁺ channels in nerves (LA) and cardiac myocytes (antiarrhythmic).
- Bupivacaine
Voltage-gated Na⁺ channel blocker. Higher protein binding and lipid solubility than lidocaine → longer duration but greater cardiotoxicity.
- Ropivacaine
S-enantiomer of propivacaine. Less lipid-soluble than bupivacaine → less cardiotoxicity but slightly less potency.
- Chloroprocaine
Na⁺-channel blocker. Extremely rapid plasma-cholinesterase metabolism (half-life seconds) → lowest systemic toxicity of the LAs, ideal for OB epidural top-up.
- Procaine
Na⁺-channel blocker; prototype ester LA. Plasma-cholinesterase metabolized to PABA.
- Prilocaine
Na⁺-channel blocker. Metabolized to o-toluidine → oxidizes hemoglobin → methemoglobinemia at high doses.
- Levobupivacaine
The S(−)-enantiomer of bupivacaine → similar block with LESS cardiotoxicity + CNS toxicity than racemic bupivacaine.
- Articaine
Amide LA that uniquely also has a thiophene ester group → partial plasma-esterase metabolism → shorter systemic half-life. Excellent bone/tissue penetration in dentistry.
Browse all classes: /reference/drugs
Suggested reading
- •Stoelting & Hines, Pharmacology & Physiology in Anesthetic Practice, 6e
- •FDA package insert
- •ASRA LAST checklist, 2020
