CARBOCAINE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for CARBOCAINE (CARBOCAINE).
Mepivacaine, the active ingredient in Carbocaine, is an amide-type local anesthetic that blocks sodium ion channels in nerve cell membranes, thereby inhibiting the initiation and conduction of nerve impulses.
| Metabolism | Mepivacaine is primarily metabolized in the liver via N-demethylation, hydroxylation, and glucuronide conjugation, predominantly by cytochrome P450 enzymes, specifically CYP1A2 and CYP3A4. |
| Excretion | Renal excretion of unchanged drug and metabolites accounts for approximately 95% of elimination, with less than 5% excreted in feces via biliary elimination. |
| Half-life | 2.0–3.5 hours in adults; prolonged in patients with hepatic impairment (up to 8–10 hours) or renal dysfunction. |
| Protein binding | 85% bound primarily to alpha-1-acid glycoprotein. |
| Volume of Distribution | 1.1–1.8 L/kg; reflects extensive tissue distribution. |
| Bioavailability | N/A (not administered orally); intravenous: 100%; epidural: complete systemic absorption; infiltration: localized with systemic absorption approaching 100%. |
| Onset of Action | Infiltration: 1–2 minutes; Epidural: 5–15 minutes; Peripheral nerve block: 10–20 minutes. |
| Duration of Action | Infiltration: 1–2 hours; Epidural: 1–2 hours (with epinephrine: 2–3 hours); Peripheral nerve block: 1.5–3 hours (with epinephrine: 3–5 hours). |
| Molecular Weight | 282.88 Da (as hydrochloride) |
1% to 2% solution, 5-20 mL local infiltration or nerve block; maximum dose 400 mg (or 7 mg/kg) per 90-minute period.
| Dosage form | INJECTABLE |
| Renal impairment | No specific GFR-based dose adjustment recommended; use with caution in severe renal impairment (CrCl <30 mL/min) due to risk of systemic accumulation. |
| Liver impairment | Child-Pugh Class A: no adjustment; Child-Pugh Class B: reduce dose by 25% and avoid large volumes; Child-Pugh Class C: avoid use due to prolonged half-life and increased systemic toxicity. |
| Pediatric use | Weight-based: up to 7 mg/kg per injection; maximum single dose 400 mg; for continuous infusion, 0.1-0.4 mg/kg/min. |
| Geriatric use | Reduce dose by 20-30% due to decreased hepatic blood flow and lower clearance; avoid doses >300 mg as a single injection. |
| 1st trimester | Mepivacaine crosses the placenta. Avoid use in early pregnancy unless clearly needed. Limited data suggest no major teratogenic risk, but fetal bradycardia may occur. |
| 2nd trimester | Use only if benefit outweighs risk. Monitor for signs of fetal bradycardia and maternal toxicity. Doses should be minimized. |
| 3rd trimester | May cause fetal bradycardia and neonatal depression. Avoid paracervical block. Use lowest effective dose; consider alternative agents. |
Clinical note
Comprehensive clinical and safety monograph for CARBOCAINE (CARBOCAINE).
| Placental transfer | Mepivacaine readily crosses the placenta. Fetal/maternal ratio is approximately 0.5–0.7. It accumulates in the fetal myocardium more than lidocaine, potentially causing cardiovascular depression. |
| Breastfeeding | Mepivacaine is excreted into breast milk in small amounts (<2% of maternal dose). Oral bioavailability in infants is low, so risk of adverse effects is minimal. However, monitor for signs of local anesthetic toxicity (e.g., irritability, poor feeding) in the infant, especially with high maternal doses or repeated administration. |
■ FDA Black Box Warning
Not all local anesthetics have a specific black box warning from the FDA. However, Carbocaine is contraindicated in patients with known hypersensitivity to amide-type local anesthetics. It should be used with caution in patients with heart block, severe hypotension, or shock.
| Serious Effects |
Hypersensitivity to mepivacaine or other amide anestheticsSevere hypotension or shockComplete heart blockMyasthenia gravis (if using ester-type or large doses; mepivacaine is amide, but use with caution)Paracervical block in pregnancy (obstetric use contraindicated due to fetal bradycardia)
| Precautions | Risk of cardiac arrhythmias and cardiac arrest if used in excessive doses or inadvertently injected intravascularly., Severe adverse reactions including CNS toxicity (seizures, respiratory depression) and cardiovascular collapse., Use with caution in patients with hepatic impairment, as metabolism may be reduced., May cause methemoglobinemia, especially in infants and patients with glucose-6-phosphate dehydrogenase deficiency., Avoid use in patients with known hypersensitivity to amide-type local anesthetics or to any component of the formulation. |
| Food/Dietary |
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| Lactation Rating | L2 (Safer) |
| Teratogenic Risk | Carbocaine (mepivacaine) is a local anesthetic. In first trimester: no well-controlled studies; animal studies have not shown teratogenicity; risk cannot be excluded. In second and third trimesters: no known fetal harm; doses used for regional anesthesia are generally safe, but high doses may cause fetal bradycardia or acidosis due to uterine artery constriction. |
| Fetal Monitoring | Monitor maternal blood pressure, heart rate, and oxygen saturation. Fetal heart rate monitoring during obstetric use to detect signs of bradycardia or late decelerations. Monitor for signs of local anesthetic systemic toxicity (LAST) including CNS changes, cardiovascular instability. |
| Fertility Effects | No human data on fertility effects; animal studies have not shown impaired fertility at clinically relevant doses. No known effect on spermatogenesis or ovulation. |
| No known food interactions with mepivacaine (Carbocaine). No dietary restrictions required. Avoid alcohol consumption for 24 hours after administration to minimize potential additive CNS depression. |
| Clinical Pearls | Carbocaine (mepivacaine) is an amide local anesthetic with rapid onset (2-4 min) and intermediate duration (45-90 min). It lacks vasodilating properties, so epinephrine is not required for vasoconstriction. It is metabolized primarily by the liver; use with caution in hepatic impairment. Avoid in patients with known hypersensitivity to amide anesthetics. For infiltration, typical 0.5-1% solutions are used; for nerve blocks, 1-2% concentrations. Maximum dose: 400 mg (7 mg/kg) without epinephrine, 550 mg (9 mg/kg) with epinephrine. Onset in epidural use is slower than lidocaine. Can cause CNS excitation (tinnitus, metallic taste) followed by depression; manage with benzodiazepines. Reduce dose in elderly or debilitated patients. |
| Patient Advice | Inform your doctor if you have any allergies, especially to local anesthetics. · Tell your healthcare provider about all medications you take, including blood thinners, heart medications, and herbal supplements. · After anesthesia, avoid driving or operating machinery until full sensation and motor function have returned. · If you experience severe headache, stiff neck, or difficulty breathing after an epidural or spinal injection, seek emergency care immediately. · Numbness or tingling after injection is normal and temporary; avoid scratching or rubbing the numb area to prevent injury. · Notify your dentist or doctor if you have liver disease, heart block, or if you are pregnant or breastfeeding. · Apply ice to the injection site if mild swelling or discomfort occurs; do not use heat. |