CHLOROPROCAINE HYDROCHLORIDE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for CHLOROPROCAINE HYDROCHLORIDE (CHLOROPROCAINE HYDROCHLORIDE).
Blocks voltage-gated sodium channels in nerve cell membranes, inhibiting conduction of nerve impulses. Exhibits rapid onset and short duration due to hydrolysis by plasma pseudocholinesterase.
| Metabolism | Rapidly hydrolyzed by plasma pseudocholinesterase (butyrylcholinesterase) to beta-diethylaminoethanol and 2-chloro-4-aminobenzoic acid. Metabolism is independent of hepatic function. |
| Excretion | Primarily renal excretion of metabolites; unchanged drug undergoes rapid hydrolysis by plasma pseudocholinesterase, producing 2-chloro-4-aminobenzoic acid and diethylaminoethanol. Less than 2% excreted unchanged in urine. Biliary/fecal elimination is negligible. |
| Half-life | Terminal elimination half-life of chloroprocaine is approximately 0.1-0.2 hours (6-12 minutes) in adults with normal pseudocholinesterase activity. This extremely short half-life accounts for its rapid clearance and short duration of action. |
| Protein binding | Approximately 50-60% bound to plasma proteins, primarily albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | Volume of distribution (Vd) is approximately 0.5-1.0 L/kg. This moderate Vd reflects distribution into total body water with some tissue binding. |
| Bioavailability | Not applicable for oral route (undergoes extensive first-pass hydrolysis). For epidural or infiltration routes, bioavailability is considered 100% as the drug is administered directly at the site of action. |
| Onset of Action | Epidural: 6-12 minutes; Caudal: 5-15 minutes; Peripheral nerve block: 10-15 minutes; Infiltration: 1-5 minutes; Intravenous regional (Bier block): 2-5 minutes. |
| Duration of Action | Epidural: 30-60 minutes (increases with epinephrine to 60-90 minutes); Peripheral nerve block: 30-60 minutes (up to 90 minutes with epinephrine); Infiltration: 20-40 minutes. Duration is dose- and concentration-dependent. |
| Molecular Weight | 307.22 Da (as hydrochloride salt) |
10-30 mL of 1% solution infiltrated locally; epidural: 15-25 mL of 2% or 3% solution, repeated as needed, not to exceed 800 mg total dose.
| Dosage form | INJECTABLE |
| Renal impairment | No specific dose adjustment recommended; use with caution in severe renal impairment due to potential for metabolite accumulation. |
| Liver impairment | No specific dose adjustment recommended; use with caution due to ester metabolism by plasma pseudocholinesterase. |
| Pediatric use | Infiltration: 0.5-1 mg/kg; epidural: 5-15 mg/kg as a 1-2% solution, dose based on age and weight, not to exceed 10 mg/kg. |
| Geriatric use | Reduce dose by 20-30% due to decreased clearance and increased sensitivity; monitor for prolonged effects. |
| 1st trimester | FDA Pregnancy Category C. Use only if benefit outweighs risk. Animal studies show fetal abnormalities at high doses. |
| 2nd trimester | FDA Pregnancy Category C. Use only if clearly needed. Consider risks of maternal hypotension and fetal acidosis. |
| 3rd trimester | FDA Pregnancy Category C. Use near term may cause neonatal CNS depression. Avoid for paracervical block due to fetal bradycardia. |
Clinical note
Comprehensive clinical and safety monograph for CHLOROPROCAINE HYDROCHLORIDE (CHLOROPROCAINE HYDROCHLORIDE).
| Placental transfer | Crosses placenta rapidly. Fetal/maternal ratio ~0.3-0.5. High protein binding limits transfer but fetal acidosis can trap drug. |
| Breastfeeding | Excreted into breast milk in small amounts. Consider risk of infant methemoglobinemia, especially in G6PD deficiency. Monitor for drowsiness, poor feeding. Generally compatible with short-term use. |
■ FDA Black Box Warning
Not available/intended for use in procedures involving large volumes or high doses near major blood vessels due to risk of systemic toxicity, including cardiac arrest and death. Resuscitative equipment and trained personnel must be immediately available.
| Serious Effects |
Known hypersensitivity to ester-type anesthetics or PABASevere hypertension (e.g., pheochromocytoma)Myasthenia gravis (relative, but caution)Concurrent use of MAOIs or tricyclic antidepressants (increased risk of hypertension)Severe bradycardia or heart blockUncontrolled seizure disorderPseudocholinesterase deficiency (risk of prolonged toxicity)Untreated hypovolemia or shock
| Precautions | Risk of systemic toxicity (CNS and cardiovascular) if injected intravascularly. Use caution in patients with pseudocholinesterase deficiency, severe hepatic disease, or cardiovascular compromise. Avoid ophthalmic use due to corneal epithelial damage. Monitor for signs of unintended intravascular injection. |
| Food/Dietary | No known food interactions. No dietary restrictions required. |
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| Lactation Rating | L3 - Moderately Safe |
| Teratogenic Risk | Chloroprocaine hydrochloride is a pregnancy category C drug. Animal reproduction studies are lacking; however, based on its pharmacologic profile as an ester-type local anesthetic with rapid hydrolysis by plasma cholinesterase, systemic fetal exposure is minimal after maternal administration. There is no evidence of teratogenicity in humans. However, use during the first trimester should be reserved for clear medical necessity. In late pregnancy or labor, local anesthetics may cross the placenta and potentially cause fetal bradycardia or central nervous system depression if high doses or inadvertent intravascular injection occur. Overall risk is low with appropriate dosing and technique. |
| Fetal Monitoring | Maternal monitoring includes continuous assessment of blood pressure, heart rate, oxygen saturation, and level of consciousness. Fetal monitoring includes fetal heart rate and uterine activity during labor. Watch for signs of systemic toxicity: perioral numbness, metallic taste, tinnitus, seizures, or cardiac arrhythmias. In obstetrical use, monitor for prolonged motor blockade or fetal bradycardia. After injection, observe for allergic reactions (rare) due to para-aminobenzoic acid metabolite. |
| Fertility Effects | There are no known adverse effects of chloroprocaine on human fertility. Animal studies have not been conducted to evaluate reproductive toxicity. Based on its pharmacologic properties, it is unlikely to impair fertility. However, use in reproductive-age women should follow standard indications for local anesthesia. |
| Clinical Pearls | Chloroprocaine is an ester-type local anesthetic with rapid onset and short duration of action. It is often used for spinal and epidural anesthesia due to low systemic toxicity. Avoid use in patients with pseudocholinesterase deficiency as it is rapidly hydrolyzed by plasma cholinesterase. Allergic reactions are rare but may occur due to cross-sensitivity with other ester anesthetics (e.g., procaine, tetracaine). |
| Patient Advice | Inform your healthcare provider if you have a history of allergic reactions to local anesthetics. · Report any signs of allergic reaction such as rash, itching, or difficulty breathing immediately. · Avoid driving or operating machinery for 24 hours after receiving this medication if it was used for a procedure that affects motor function. · Notify your doctor if you are pregnant or breastfeeding before receiving chloroprocaine. · If you experience persistent numbness, weakness, or pain after the anesthetic wears off, seek medical attention. |