PROCAINE HYDROCHLORIDE W/ EPINEPHRINE
Clinical safety rating: safe
Beta-blockers may antagonize cardiac effects and cause severe hypertension Can cause angina and arrhythmias in patients with heart disease.
Procaine is a local anesthetic that blocks voltage-gated sodium channels, preventing nerve impulse conduction. Epinephrine causes vasoconstriction via alpha-1 adrenergic receptor agonism, reducing absorption of procaine and prolonging its effect.
| Metabolism | Procaine is hydrolyzed by plasma pseudocholinesterase (butyrylcholinesterase) to para-aminobenzoic acid (PABA) and diethylaminoethanol. Epinephrine is metabolized by catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO). |
| Excretion | Renal excretion of procaine is minimal as it is rapidly hydrolyzed by plasma pseudocholinesterase to para-aminobenzoic acid (PABA) and diethylaminoethanol (DEAE). Less than 2% of unchanged procaine is excreted in urine. Metabolites are further processed and eliminated renally. Epinephrine is metabolized by catechol-O-methyltransferase and monoamine oxidase; metabolites are excreted in urine. |
| Half-life | Procaine: 40–84 seconds (plasma), due to rapid hydrolysis. The terminal elimination half-life of procaine is approximately 7–8 minutes after hydrolysis, but the clinical effect is terminated by redistribution and metabolism. Epinephrine: 2–3 minutes. |
| Protein binding | Procaine: negligible (<5%). Epinephrine: 15–20% (primarily albumin and alpha-1-acid glycoprotein). |
| Volume of Distribution | Procaine: approximately 1.0 L/kg, indicating extensive distribution into tissues. Epinephrine: 0.28 L/kg (for endogenous levels). |
| Bioavailability | Procaine: Not administered orally due to extensive first-pass hydrolysis; intramuscular absorption is rapid. Intravenous: 100%. Epinephrine: Not orally bioavailable; intravenous and intramuscular provide 100% systemic exposure. |
| Onset of Action | Infiltration and nerve block: 2–5 minutes. Epidural: 5–15 minutes. Intrathecal: immediate to 5 minutes. Topical application: not effective due to poor penetration. |
| Duration of Action | Infiltration: 30–60 minutes (with epinephrine, prolonged to 60–90 minutes). Nerve block: 30–90 minutes (with epinephrine, 60–180 minutes). Epidural: 30–60 minutes (with epinephrine, 45–90 minutes). Intrathecal: 30–60 minutes. Epinephrine prolongs duration by vasoconstriction. |
2% procaine hydrochloride with epinephrine 1:200,000: Local infiltration or nerve block: up to 25 mL (500 mg procaine) as a single dose; maximum total dose 1000 mg per procedure. For epidural or spinal anesthesia: 5-20 mL (100-400 mg) as needed.
| Dosage form | INJECTABLE |
| Renal impairment | No specific dose adjustment required for GFR >30 mL/min. For GFR 15-30 mL/min: reduce dose by 25% and monitor for toxicity. For GFR <15 mL/min: avoid or use with extreme caution; maximum single dose 200 mg. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B: reduce dose by 50% and monitor. Child-Pugh C: contraindicated. |
| Pediatric use | Infiltration anesthesia: 0.5-1 mL/kg of 0.5% solution (max 5 mg/kg per dose). Nerve block: 0.5-1 mL/kg of 1% solution (max 5 mg/kg). Maximum single dose: 5 mg/kg; maximum total dose 200 mg. |
| Geriatric use | Reduce doses by 20-40% due to decreased clearance and increased sensitivity. Use lower concentrations and volumes. Avoid in patients with severe cardiovascular disease. Maximum single dose 500 mg. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Beta-blockers may antagonize cardiac effects and cause severe hypertension Can cause angina and arrhythmias in patients with heart disease.
| FDA category | Animal |
| Breastfeeding | Procaine and epinephrine are excreted into breast milk in low amounts. M/P ratio not established. Consider use during breastfeeding only if clearly needed; observe infant for adverse effects. |
| Teratogenic Risk | FDA Pregnancy Category C. Procaine crosses the placenta. No well-controlled studies in pregnant women. Epinephrine may reduce uterine blood flow and cause fetal hypoxia; avoid in second stage of labor. Risk of methemoglobinemia in fetus and neonate with procaine. |
■ FDA Black Box Warning
Not for use in patients with known hypersensitivity to para-aminobenzoic acid (PABA) or other ester-type anesthetics. Solutions containing epinephrine should not be used in areas of end-arteries (e.g., digits, nose, ears) due to risk of ischemic necrosis.
| Common Effects | cardiac arrest |
| Serious Effects |
Hypersensitivity to procaine, epinephrine, or ester-type anesthetics. Infection at injection site. Severe hypertension, hyperthyroidism, or narrow-angle glaucoma (with epinephrine). Use in areas with compromised blood supply (digits, ears, penis).
| Precautions | Risk of systemic toxicity (CNS stimulation followed by depression, cardiovascular collapse). Use with caution in patients with hepatic impairment, pseudocholinesterase deficiency, or cardiovascular disease. Avoid intravascular injection. Epinephrine may cause hypertension and arrhythmias. |
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| Fetal Monitoring | Monitor maternal blood pressure, heart rate, and fetal heart rate during administration. Assess for signs of maternal or fetal distress (e.g., bradycardia, hypoxia). |
| Fertility Effects | No known adverse effects on fertility in animal studies. Limited human data; procaine and epinephrine are unlikely to impair fertility at clinical doses. |