XYLOCAINE 1.5% W/ DEXTROSE 7.5%
Clinical safety rating: caution
Comprehensive clinical and safety monograph for XYLOCAINE 1.5% W/ DEXTROSE 7.5% (XYLOCAINE 1.5% W/ DEXTROSE 7.5%).
Lidocaine is an amide-type local anesthetic that blocks sodium channels, thereby inhibiting the propagation of action potentials in peripheral nerves, leading to local anesthesia.
| Metabolism | Hepatic metabolism via CYP1A2 and CYP3A4, primarily to monoethylglycinexylidide (MEGX) and glycinexylidide (GX), which are less active. |
| Excretion | Renal excretion of metabolites (predominantly 4-hydroxy-2,6-xylidine and conjugates) accounts for >80% of elimination; less than 10% eliminated unchanged in urine. Biliary/fecal excretion of metabolites contributes <10%. |
| Half-life | Terminal elimination half-life: 1.5–2 hours in adults with normal hepatic function; may be prolonged to 3–5 hours in patients with hepatic impairment or congestive heart failure. |
| Protein binding | Approximately 65–75% bound primarily to alpha-1-acid glycoprotein (AAG) and to a lesser extent albumin. Binding is concentration-dependent and decreases at high concentrations. |
| Volume of Distribution | Vd: 0.8–1.3 L/kg. Represents extensive tissue distribution and rapid equilibration from plasma into well-perfused organs (brain, heart, liver, kidneys). Increased Vd in neonates and elderly. |
| Bioavailability | Epidural: near 100% (due to vascular absorption from epidural space); Absorption from injection site depends on vascularity and dose. Oral: negligible (<5%) due to extensive first-pass metabolism. |
| Onset of Action | Epidural: 5–15 minutes; Spinal: within 1–2 minutes; Peripheral nerve block: 5–15 minutes; Infiltration: 1–2 minutes. |
| Duration of Action | Epidural: 60–90 minutes of surgical anesthesia (time to regression of sensory level by 2 dermatomes); Spinal: 45–60 minutes of surgical anesthesia; Peripheral nerve block: 1–3 hours depending on dose and technique. Addition of epinephrine may prolong duration by 30–50%. |
Spinal anesthesia: 1.5-2 mL (22.5-30 mg lidocaine) for lower extremity or perineal procedures; 2-3 mL (30-45 mg) for lower abdominal or urological procedures. Administered via lumbar puncture.
| Dosage form | INJECTABLE |
| Renal impairment | No specific dose adjustment required for spinal administration; however, monitor for systemic toxicity in severe renal impairment (CrCl <30 mL/min). |
| Liver impairment | Child-Pugh Class A: no adjustment. Child-Pugh Class B/C: reduce dose by 50% and monitor for prolonged anesthesia and toxicity. |
| Pediatric use | Not FDA-approved for pediatric spinal anesthesia. Weight-based dosing for other routes of lidocaine: 1.5-2 mg/kg as a single spinal dose, administered by anesthesiologist. |
| Geriatric use | Reduce dose by 30-50% due to decreased CSF volume and prolonged neural blockade. Use low end of adult range (1.5-2 mL) and monitor for hypotension and bradycardia. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for XYLOCAINE 1.5% W/ DEXTROSE 7.5% (XYLOCAINE 1.5% W/ DEXTROSE 7.5%).
| Breastfeeding | Lidocaine is excreted into breast milk in small amounts. The milk-to-plasma (M/P) ratio is approximately 0.4. At therapeutic doses, the estimated relative infant dose is less than 4% of the maternal weight-adjusted dose, which is considered compatible with breastfeeding. However, caution should be used with high doses or prolonged use due to potential accumulation in the infant. |
| Teratogenic Risk | Lidocaine is classified as FDA pregnancy category B. Animal studies have not demonstrated fetal risk, but no adequate human studies exist. There is no evidence of teratogenicity in humans when used at recommended doses. However, use in the first trimester should be based on necessity. In the second and third trimesters, lidocaine is generally considered safe, but caution is advised due to potential fetal bradycardia or central nervous system depression if high systemic levels occur. The dextrose component at 7.5% is not considered teratogenic. |
■ FDA Black Box Warning
Not all local anesthetics for infiltration or nerve block are approved for spinal anesthesia; this formulation is not approved for spinal anesthesia. Use only as directed.
| Common Effects | Allergic reaction Application site reactions burning irritation itching and redness |
| Serious Effects |
Hypersensitivity to lidocaine or amide-type anesthetics, severe hypotension, complete heart block (for IV use).
| Precautions | Risk of systemic toxicity including CNS excitation/depression and cardiac depression; use with caution in patients with hepatic impairment, cardiac disease, or elderly. Avoid intravascular injection; monitor for signs of toxicity. Resuscitative equipment should be available. |
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| Fetal Monitoring | Monitor maternal vital signs (heart rate, blood pressure, respiratory rate) and signs of systemic toxicity (dizziness, tinnitus, perioral numbness, seizures). Fetal heart rate monitoring is recommended during labor and delivery to detect bradycardia. Assess for signs of local anesthetic systemic toxicity (LAST) including central nervous system and cardiovascular effects. |
| Fertility Effects | Lidocaine has no known direct effects on human fertility. In animal studies, no impairment of fertility was observed at clinically relevant doses. However, the dextrose component at 7.5% may cause transient hyperglycemia but does not affect fertility. |