CITANEST PLAIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for CITANEST PLAIN (CITANEST PLAIN).
Blocks sodium channels, inhibiting nerve impulse conduction.
| Metabolism | Hepatic via CYP1A2 and amidases to inactive metabolites. |
| Excretion | Prilocaine is metabolized primarily in the liver via amidases, with major metabolites including o-toluidine and N-propylalanine. Approximately 50-70% of the dose is excreted renally as metabolites, with less than 2% excreted unchanged in urine. Biliary/fecal excretion is minimal (<5%). |
| Half-life | The terminal elimination half-life of prilocaine is approximately 1.5 hours in adults with normal hepatic and renal function. In neonates, the half-life may be prolonged to 3-4 hours due to immature hepatic metabolism. This short half-life supports its use for procedures requiring moderate duration of anesthesia. |
| Protein binding | Prilocaine is approximately 55% bound to plasma proteins, primarily albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | The volume of distribution at steady state is about 1.0-1.5 L/kg, indicating extensive distribution into tissues, including the central nervous system and placenta. |
| Bioavailability | Bioavailability for infiltration and nerve blocks is approximately 100% as the drug is administered directly at the site of action. For epidural administration, systemic absorption yields high bioavailability but is not applicable as a primary measure for local anesthetics. Oral bioavailability is negligible due to extensive first-pass metabolism (<5%). |
| Onset of Action | For infiltration and peripheral nerve blocks, onset occurs within 2-5 minutes. For epidural administration, onset is 5-15 minutes. The rapid onset is attributed to the drug's pKa (7.9) and high lipid solubility. |
| Duration of Action | Duration of anesthesia for infiltration and peripheral nerve blocks is 1-2 hours, depending on dose and vascularity of the site. For epidural use, duration is 30-60 minutes. Addition of epinephrine (not present in Citanest Plain) may prolong duration. |
Prilocaine 1-2% solution: local infiltration, 1-20 mL of 1-2% (10-400 mg); nerve block, 10-40 mL of 1-2% (100-800 mg); epidural, 15-30 mL of 2% (300-600 mg). Maximum dose: 8 mg/kg (600 mg) as single dose, not to exceed 600 mg without epinephrine.
| Dosage form | INJECTABLE |
| Renal impairment | No specific dose adjustment required for mild to moderate renal impairment; use with caution in severe renal impairment (GFR <30 mL/min) due to potential accumulation of metabolites; monitor for methemoglobinemia. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 25-50%; Child-Pugh C: contraindicated due to risk of systemic toxicity and methemoglobinemia. |
| Pediatric use | Max dose: 8 mg/kg (5 mg/kg for infants <6 months); typical infiltration: 0.5-2 mg/kg; nerve block: 1-4 mg/kg; monitor for methemoglobinemia especially in neonates and infants. |
| Geriatric use | Reduce dose by 20-40% due to decreased clearance and increased risk of toxicity; use lowest effective dose; monitor for CNS and cardiovascular adverse effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for CITANEST PLAIN (CITANEST PLAIN).
| Breastfeeding | Lidocaine is excreted in breast milk in small amounts. M/P ratio is approximately 0.4. After a single dose, peak milk concentration is about 0.8-1.2 mcg/mL. No adverse effects reported in nursing infants. Use with caution; monitor infant for signs of local anesthetic toxicity. |
| Teratogenic Risk | FDA Pregnancy Category C. No adequate studies in pregnant women. In animal studies, lidocaine (active component) caused fetal toxicity at doses 6-7 times the maximum human dose. Risk cannot be ruled out. First trimester: Use only if clearly needed. Second and third trimesters: May cause fetal bradycardia and acidosis if large doses are administered paracervically. |
■ FDA Black Box Warning
Not available (no FDA boxed warning).
| Serious Effects |
["Hypersensitivity to amide anesthetics","Severe hypovolemia","Myasthenia gravis (for epidural use)"]
| Precautions | ["Risk of cardiac arrest and arrhythmias with high doses","Allergic reactions to amide-type anesthetics","Methemoglobinemia, especially in neonates"] |
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| Fetal Monitoring | Monitor maternal vital signs (blood pressure, heart rate, respiratory rate) and ECG. Fetal heart rate monitoring during paracervical block. Monitor for signs of systemic toxicity (CNS excitation, seizures, arrhythmias). |
| Fertility Effects | No evidence of impaired fertility in animal studies. In humans, no known adverse effects on fertility. Local anesthetics are not expected to affect reproductive function. |