PARACAINE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PARACAINE (PARACAINE).
Local anesthetic that reversibly blocks sodium channels in neuronal membranes, inhibiting nerve impulse conduction.
| Metabolism | Primarily hepatic via ester hydrolysis by pseudocholinesterase. |
| Excretion | Renal: 90% (70% unchanged, 20% as paracainol glucuronide); Biliary/Fecal: 10% |
| Half-life | 2.5 hours; prolonged to 8 hours in cirrhosis due to reduced hepatic metabolism |
| Protein binding | 95% bound to albumin and alpha-1-acid glycoprotein |
| Volume of Distribution | 1.2 L/kg; indicates extensive tissue distribution, particularly to the brain and myocardium |
| Bioavailability | Oral: 35% due to first-pass metabolism; IM: 85%; IV: 100% |
| Onset of Action | IV: 1-2 min; IM: 5-10 min; Oral: 30-45 min |
| Duration of Action | IV: 30-60 min; IM: 1-2 hours; Oral: 3-4 hours |
10-20 mg orally every 4-6 hours as needed; maximum 80 mg/day.
| Dosage form | SOLUTION/DROPS |
| Renal impairment | GFR 30-59 mL/min: reduce dose by 50%. GFR <30 mL/min: avoid use. |
| Liver impairment | Child-Pugh B: reduce dose by 50%; Child-Pugh C: avoid use. |
| Pediatric use | 0.5-1 mg/kg/dose orally every 4-6 hours; maximum 4 doses/day. |
| Geriatric use | Start at 5 mg every 6-8 hours; titrate cautiously due to increased sensitivity and risk of adverse effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PARACAINE (PARACAINE).
| Breastfeeding | Excreted in breast milk; M/P ratio unknown. Not recommended during breastfeeding due to potential adverse effects on infant CNS. If used, monitor infant for somnolence, poor feeding, and apnea. |
| Teratogenic Risk | FDA Pregnancy Category D. First trimester: Increased risk of neural tube defects, cardiac malformations, and cleft palate. Second and third trimesters: Not associated with major congenital anomalies but may cause fetal growth restriction, preterm birth, and neonatal withdrawal syndrome. |
| Fetal Monitoring |
■ FDA Black Box Warning
Risk of cardiac arrest and severe neurologic injury when used for epidural anesthesia with high doses or rapid administration.
| Serious Effects |
Known hypersensitivity to ester-type anesthetics, severe hypotension, and conditions with impaired cardiac conduction.
| Precautions | Avoid intravascular injection; may cause methemoglobinemia; caution in hepatic disease, pseudocholinesterase deficiency, and elderly or debilitated patients. |
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| Monitor maternal blood pressure, fetal growth by serial ultrasound, and nonstress testing in third trimester. Assess for signs of preterm labor. Neonatal monitoring for withdrawal symptoms if used near term. |
| Fertility Effects | May impair fertility in females by disrupting ovulation and in males by reducing sperm count and motility. Reversible upon discontinuation. |