Cocaine
(topical, ENT)
Ester local anesthetic + sympathomimetic (topical)
Na⁺-channel block (LA) PLUS blockade of norepinephrine reuptake → vasoconstriction. The only LA that is intrinsically vasoconstrictive.
Indications
- •Topical anesthesia + vasoconstriction for nasal/ENT procedures
Dosing
| Context | Adult | Pediatric |
|---|---|---|
| Topical ENT | 4% solution; typical max ~1.5–3 mg/kg | — |
Pharmacokinetics
Onset ~1 min topical. Duration ~30–60 min. Plasma + hepatic cholinesterase metabolism.
Side effects
- !Hypertension, tachycardia, coronary vasospasm, arrhythmia
- !CNS toxicity/seizures
- !Wide-complex (Na-channel) toxicity
Contraindications
- ×Coronary disease / recent MI
- ×Uncontrolled HTN
- ×MAOI/sympathomimetic use
- ×Avoid unopposed β-blockade
Clinical pearls
- ★Unique among LAs: built-in vasoconstriction (NE reuptake block) — hence ENT topical use.
- ★Treat cocaine cardiac toxicity with benzodiazepines ± nitroglycerin/phentolamine; AVOID unopposed β-blockers.
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.
- Tetracaine
Blocks voltage-gated Na⁺ channels. Long-acting ester, metabolized by plasma cholinesterase. High potency + toxicity.
- 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.
Suggested reading
- •Stoelting & Hines, Pharmacology & Physiology in Anesthetic Practice, 6e
- •FDA package insert
- •ASRA LAST checklist, 2020
