ALPHACAINE HYDROCHLORIDE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ALPHACAINE HYDROCHLORIDE (ALPHACAINE HYDROCHLORIDE).
Local anesthetic that reversibly blocks sodium ion channels in neuronal membranes, preventing the generation and propagation of action potentials.
| Metabolism | Hydrolyzed by plasma pseudocholinesterases to para-aminobenzoic acid and diethylaminoethanol. |
| Excretion | Primarily renal excretion of unchanged drug and metabolites (70-80%); minor biliary elimination (10-15%); fecal excretion <5%. |
| Half-life | Terminal half-life 2.5-3.5 hours in adults; prolonged to 4-6 hours in hepatic impairment or elderly. |
| Protein binding | 90-95% bound to alpha-1-acid glycoprotein and albumin. |
| Volume of Distribution | Vd 0.8-1.2 L/kg; extensive tissue distribution (liver, lungs, brain). |
| Bioavailability | Oral: 30-40% (first-pass metabolism); Intramuscular: 85-95%; Intravenous: 100%. |
| Onset of Action | Intravenous: 30-60 seconds; Intramuscular: 2-5 minutes; Oral: 15-30 minutes. |
| Duration of Action | Intravenous: 15-20 minutes; Intramuscular: 30-60 minutes; Oral: 1-2 hours due to rapid redistribution and metabolism. |
| Molecular Weight | 234.4 |
1–2% solution via local infiltration or nerve block, up to a maximum of 4.5 mg/kg (or 300 mg) without epinephrine; with epinephrine, maximum 7 mg/kg (or 500 mg).
| Dosage form | INJECTABLE |
| Renal impairment | No specific dose adjustment required; use with caution in severe renal impairment (CrCl <30 mL/min) due to potential accumulation. Monitor for CNS toxicity. |
| Liver impairment | Child-Pugh Class A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: avoid use or use alternative agent. |
| Pediatric use | Local infiltration: 0.5–2% solution, maximum 4.5 mg/kg (without epinephrine) or 7 mg/kg (with epinephrine). For nerve blocks: weight-based dosing, not to exceed adult maximum. |
| Geriatric use | Reduce total dose by 20–30% due to decreased clearance and increased sensitivity; monitor for prolonged effect and toxicity. |
| 1st trimester | Avoid. No adequate studies in pregnant women. Animal studies have shown teratogenic effects at high doses. |
| 2nd trimester | Use only if clearly needed. Potential risk of fetal bradycardia and central nervous system depression. |
| 3rd trimester | Use only if clearly needed. Risk of neonatal respiratory depression and altered fetal heart rate. |
Clinical note
Comprehensive clinical and safety monograph for ALPHACAINE HYDROCHLORIDE (ALPHACAINE HYDROCHLORIDE).
| Placental transfer | Crosses placenta readily through passive diffusion. The fetal-to-maternal ratio is approximately 0.5-0.7. |
| Breastfeeding | Alphacaine hydrochloride is excreted into breast milk in small amounts. The relative infant dose is <2% of the maternal weight-adjusted dose, unlikely to cause adverse effects in the infant. Monitor for signs of local anesthetic toxicity. |
■ FDA Black Box Warning
Not available.
| Serious Effects |
Hypersensitivity to alphacaine or other amide-type local anestheticsSevere hypotensionComplete heart blockMyasthenia gravisSevere liver disease
| Precautions | Risk of systemic toxicity if absorbed into circulation, Hypersensitivity to ester-type anesthetics, Potential for methemoglobinemia with high doses, Use with caution in patients with impaired cardiac or hepatic function |
| Food/Dietary | No known food interactions. Avoid excessive grapefruit or grapefruit juice consumption due to potential CYP3A4 inhibition. |
| Clinical Pearls |
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| Lactation Rating | L1 (Safe) |
| Teratogenic Risk | Alphacaine hydrochloride is a local anesthetic; limited human data but animal studies show no teratogenicity at clinically relevant doses. Fetal risk cannot be excluded; avoid in first trimester if possible. |
| Fetal Monitoring | Monitor maternal blood pressure, heart rate, and oxygen saturation. Fetal heart rate monitoring during prolonged use. |
| Fertility Effects | No known adverse effects on human fertility based on limited data. |
| Alphacaine Hydrochloride is an amide-type local anesthetic similar to lidocaine. Onset of action is 2-5 minutes with duration of 30-120 minutes depending on concentration and use of epinephrine. It is hepatically metabolized (CYP3A4) and renally excreted. Dose adjustment required in hepatic impairment. Risk of methemoglobinemia, especially in infants and patients on sulfonamides. Do not exceed maximum doses: 4.5 mg/kg plain, 7 mg/kg with epinephrine. |
| Patient Advice | Avoid alcohol consumption for 24 hours after procedure. · Inform your doctor if you have liver disease, heart block, or history of methemoglobinemia. · Do not drive or operate machinery until effects wear off. · Report numbness, tingling, or twitching immediately. · For dental procedures: avoid eating until numbness resolves to prevent injury. |