SENSORCAINE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SENSORCAINE (SENSORCAINE).
SENSORCAINE (bupivacaine) is an amide-type local anesthetic that blocks sodium ion channels in nerve cell membranes, thereby inhibiting depolarization and propagation of action potentials, resulting in reversible local anesthesia.
| Metabolism | Primarily metabolized by the liver via conjugation with glucuronic acid; also hydrolyzed by plasma pseudocholinesterase to form pipecolylxylidine (PPX), the major metabolite. |
| Excretion | SENSORCAINE (bupivacaine) is primarily metabolized in the liver via conjugation with glucuronic acid and undergoes hepatic dealkylation. Approximately 6% of the drug is excreted unchanged in the urine. The majority of the dose (about 95%) is excreted as metabolites in the urine (<10% unchanged) and the remainder in feces via biliary elimination. |
| Half-life | The terminal elimination half-life of bupivacaine is approximately 2.7 hours in adults (range 1.5–5.5 hours). In neonates, the half-life is significantly prolonged (~8–12 hours) due to immature hepatic function, leading to an increased risk of toxicity. |
| Protein binding | Bupivacaine is highly protein-bound (~95%) primarily to alpha-1-acid glycoprotein (AAG) and to a lesser extent albumin. Binding is concentration-dependent and saturable; increased free fraction in conditions with low AAG (e.g., pregnancy, neonates, critical illness). |
| Volume of Distribution | Volume of distribution (Vd) at steady state is approximately 0.6–1.0 L/kg in adults (range 50–100 L). The large Vd reflects extensive tissue distribution, with rapid uptake into well-perfused organs (brain, heart, liver, kidneys). |
| Bioavailability | Bioavailability after epidural administration is approximately 98% due to extensive vascular absorption from the epidural space. For intravenous administration, bioavailability is 100%. Oral bioavailability is low (~30–40%) due to extensive first-pass metabolism. |
| Onset of Action | Onset of action varies by route: Epidural (lumbar): 15–25 minutes for surgical anesthesia; Caudal: 6–10 minutes; Peripheral nerve block: 10–15 minutes; Local infiltration: 1–5 minutes; Intrathecal: rapid (<5 minutes). |
| Duration of Action | Duration is dose-dependent: Epidural: 2–4 hours for surgical anesthesia (up to 6 hours with epinephrine); Peripheral nerve block: 3–8 hours; Local infiltration: 1–3 hours. Prolonged duration due to high protein binding and slow release from tissue binding sites. |
| Molecular Weight | 370.51 |
Epidural or caudal block: 15-30 mL of 0.5% to 1% solution (75-150 mg) every 2-4 hours as needed. Maximum single dose: 225 mg.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for mild to moderate impairment (GFR ≥30 mL/min). Severe impairment (GFR <30 mL/min): reduce dose by 50% and monitor for CNS toxicity. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B: reduce dose by 50%. Child-Pugh C: contraindicated. |
| Pediatric use | Neonates and infants: 0.5-1 mg/kg by infiltration or nerve block, maximum 4 mg/kg/day. Children: 1-2 mg/kg per dose, maximum 5 mg/kg/day. |
| Geriatric use | Reduce initial dose by 30-50% due to reduced clearance and increased sensitivity; titrate carefully. |
| 1st trimester | No well-controlled studies; use only if clearly needed. Animal studies have shown adverse effects at high doses. |
| 2nd trimester | Available data do not indicate fetal risk; use with caution. |
| 3rd trimester | Use near term may cause neonatal CNS depression and apnea; avoid for obstetrical paracervical block. |
Clinical note
Comprehensive clinical and safety monograph for SENSORCAINE (SENSORCAINE).
| Placental transfer | Crosses placenta by passive diffusion; rate and extent depend on protein binding and ionization. Fetal/maternal ratio approximately 0.3–0.5. |
| Breastfeeding | Excreted in breast milk in small amounts; unlikely to cause adverse effects in the infant due to poor oral bioavailability. Consider risk of accumulation with repeated doses. |
■ FDA Black Box Warning
SENSORCAINE with epinephrine is not recommended for obstetrical use (paracervical block) as it can cause fetal bradycardia and death. All local anesthetics, including bupivacaine, may cause methemoglobinemia.
| Serious Effects |
History of hypersensitivity to bupivacaine or any amide anestheticSevere hypotensionComplete heart blockObstetrical paracervical block (contraindicated for this use)
| Precautions | Risk of cardiac arrest and death with high doses or rapid injection, especially in elderly or debilitated patients, Chondrolysis risk with intra-articular infusions, Neurologic injury with spinal/epidural use, Methemoglobinemia risk, especially in neonates, Hypotension and bradycardia with epidural use, Systemic toxicity from accidental intravascular injection |
| Food/Dietary | No significant food interactions. Avoid alcohol consumption as it may increase the risk of central nervous system depression. |
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| Lactation Rating |
| L2 |
| Teratogenic Risk | Sensorcaine (bupivacaine) is classified as FDA Pregnancy Category C. In the first trimester, there is a potential risk of developmental abnormalities based on animal studies showing increased fetal resorptions and delayed ossification at high doses. During the second and third trimesters, no significant teratogenic effects have been reported in humans, but the drug may cause fetal bradycardia and metabolic acidosis due to increased placental transfer near term. Use only if clearly needed. |
| Fetal Monitoring | Monitor maternal heart rate, blood pressure, and respiratory status during administration. Fetal heart rate monitoring is recommended during labor and delivery due to possible fetal bradycardia. Assess for signs of local anesthetic systemic toxicity (LAST) including dizziness, perioral numbness, and convulsions. |
| Fertility Effects | No adverse effects on fertility have been reported with bupivacaine. Animal studies show no impairment of fertility at clinically relevant doses. However, high doses may cause transient changes in sperm motility in animal models; clinical significance in humans is unknown. |
| Clinical Pearls | Sensorcaine (bupivacaine) is a long-acting amide local anesthetic. Due to high cardiac toxicity, use low concentrations (0.25-0.5%) for peripheral nerve blocks and avoid intravascular injection. Maximum dose: 2 mg/kg (with epinephrine 3 mg/kg). Not recommended for obstetrical paracervical block. Use with caution in hepatic impairment. Levobupivacaine is the S-enantiomer with lower cardiotoxicity. |
| Patient Advice | You may experience temporary numbness or loss of sensation in the injected area. · Avoid driving or operating machinery until sensation fully returns. · Report any signs of allergic reaction, such as rash, swelling, or difficulty breathing. · Do not rub or massage the injection site to prevent spread of the drug. · Contact your healthcare provider if numbness persists beyond the expected duration. |