TETRACAINE HYDROCHLORIDE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for TETRACAINE HYDROCHLORIDE (TETRACAINE HYDROCHLORIDE).
Tetracaine hydrochloride is a local anesthetic of the ester type that reversibly blocks nerve conduction by decreasing sodium ion permeability across the neuronal membrane, thereby stabilizing the membrane and preventing the initiation and transmission of nerve impulses.
| Metabolism | Metabolized primarily by plasma pseudocholinesterases via hydrolysis to para-aminobenzoic acid (PABA) and diethylaminoethanol. |
| Excretion | Primarily metabolized by plasma pseudocholinesterase; renal excretion of metabolites accounts for >95% of elimination, with <2% excreted unchanged in urine. Biliary/fecal elimination is negligible. |
| Half-life | Terminal elimination half-life is approximately 1.5–3 minutes in plasma due to rapid hydrolysis; clinical effect duration is dose-dependent (15–30 minutes for topical anesthesia). |
| Protein binding | Approximately 75–80% bound to plasma proteins, primarily albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | Vd ~1.0–1.5 L/kg, indicating extensive tissue distribution; typical total Vd ~70 L in a 70 kg adult. |
| Bioavailability | Systemic bioavailability after topical application is minimal due to rapid local metabolism; oral bioavailability is negligible due to first-pass hydrolysis. For epidural/intrathecal, bioavailability is essentially 100% at the site of action. |
| Onset of Action | Topical (ophthalmic): 30–60 seconds; topical (mucosal): 1–3 minutes; epidural: 5–10 minutes; intrathecal: immediate to 5 minutes. |
| Duration of Action | Topical (ophthalmic): 15–30 minutes; topical (mucosal): 30–60 minutes; epidural: 1.5–3 hours; intrathecal: 1–2 hours; prolonged with epinephrine. |
Topical: 0.5-2% solution or ointment applied to affected area up to 4 times daily as needed. Maximum single dose: 20 mL of 2% solution (400 mg). Spinal anesthesia: 0.5% solution, 2-3 mL (10-15 mg) injected intrathecally.
| Dosage form | SOLUTION |
| Renal impairment | No specific dose adjustment recommended; tetracaine is metabolized primarily by plasma esterases and hepatic microsomal enzymes, with minimal renal excretion. Use caution in severe renal impairment due to potential accumulation of metabolites. |
| Liver impairment | Child-Pugh Class A: No adjustment. Child-Pugh Class B: Reduce dose by 25-50% and monitor for toxicity. Child-Pugh Class C: Avoid use or use with extreme caution; consider alternative agents due to reduced metabolism. |
| Pediatric use | Topical: Apply sparingly to limited areas; not recommended for infants <1 year. For children >1 year, maximum application area: 10% body surface area. Dose per application: 0.1-0.2 mL/kg of 1% solution; maximum total dose: 4 mg/kg. Avoid repeated use. |
| Geriatric use | Reduce dose by 25-50% due to decreased hepatic esterase activity and reduced protein binding. Use lower concentrations (e.g., 0.5% instead of 1-2%) and limit application area. Monitor for prolonged effects and systemic toxicity. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for TETRACAINE HYDROCHLORIDE (TETRACAINE HYDROCHLORIDE).
| Breastfeeding | Tetracaine is poorly absorbed orally and has low systemic bioavailability. M/P ratio is not available; however, excretion into breast milk is expected to be negligible due to rapid plasma hydrolysis by pseudocholinesterase. American Academy of Pediatrics classifies as compatible with breastfeeding. No known adverse effects on nursing infants with standard topical or regional use. |
| Teratogenic Risk | Tetracaine hydrochloride is a local anesthetic of the ester class. Animal studies are insufficient, and there are no adequate human studies in pregnant women. Systemic absorption is minimal with topical or regional use, but high-dose systemic exposure could potentially cause fetal bradycardia or CNS depression. The drug is not known to be teratogenic; risk is likely low when used as indicated. First trimester: theoretical risk from systemic toxicity, but no documented teratogenicity. Second trimester: safe for regional anesthesia with proper dosing. Third trimester: avoid high doses near delivery due to potential neonatal CNS and cardiac effects. |
■ FDA Black Box Warning
Risk of cardiac arrest and death when used for spinal anesthesia in doses exceeding recommended maximum; avoid use in patients with preexisting cardiovascular conditions.
| Serious Effects |
["Hypersensitivity to tetracaine or other ester local anesthetics","Hypersensitivity to PABA or PABA-containing products","Severe hypotension or shock","Infection at the injection site (for spinal anesthesia)","History of methemoglobinemia (relative contraindication)"]
| Precautions | ["Risk of anaphylaxis in patients with hypersensitivity to ester-type anesthetics or PABA-containing products","Severe hypotension and bradycardia during spinal anesthesia","Neurologic toxicity, including cauda equina syndrome, with high doses or intrathecal administration","Use with caution in patients with hepatic impairment, renal impairment, or cardiac disease","Avoid in myasthenia gravis due to potential for prolonged neuromuscular blockade"] |
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| Fetal Monitoring | Monitor maternal vital signs (heart rate, blood pressure, respiratory rate) during administration. Observe for signs of systemic toxicity (metallic taste, tinnitus, perioral numbness, convulsions). Fetal heart rate monitoring is recommended if used during labor (e.g., epidural) to detect bradycardia. For topical use, no specific monitoring required beyond standard clinical observation. |
| Fertility Effects | No studies on human fertility. Animal studies do not indicate impaired fertility. Tetracaine is not expected to affect fertility in males or females at clinical doses. High systemic doses could theoretically cause transient ovarian or testicular dysfunction, but no evidence exists. |