8.1 Pregnancy
Risk Summary
Local anesthetics including mepivacaine rapidly cross the placenta, and when used for epidural, paracervical, caudal, or pudendal block anesthesia, can cause varying degrees of maternal, fetal, and neonatal toxicity [see Clinical Considerations, see Clinical Pharmacology (12.3)]. The incidence and degree of toxicity depend upon the procedure performed, the type, frequency, and amount of drug used, and the technique of drug administration. Available data for mepivacaine use in pregnant women in early pregnancy are insufficient to establish a drug associated risk of major birth defects or miscarriage.
Animal reproduction studies have not been conducted with mepivacaine. Mepivacaine hydrochloride should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus [see Clinical Considerations].
The background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defects, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively.
Clinical Considerations
Labor or Delivery
Adverse reactions in the parturient, fetus, and neonate involve alterations of the CNS, peripheral vascular tone, and cardiac function. Epidural, paracervical, caudal, or pudendal anesthesia may alter the forces of parturition through changes in uterine contractility or maternal expulsive efforts. Epidural anesthesia has been reported to prolong the second stage of labor by removing the parturient’s reflex urge to bear down or by interfering with motor function. The use of obstetrical anesthesia may increase the need for forceps assistance.
Maternal Adverse Reactions
Maternal hypotension has resulted from regional anesthesia. The supine position is dangerous in pregnant women at term because of aortocaval compression by the gravid uterus. Therefore, during treatment of systemic toxicity, maternal hypotension or fetal bradycardia following regional block, the parturient should be maintained in the left lateral decubitus position if possible, or manual displacement of the uterus off the great vessels be accomplished. Elevating the patient’s legs will also help prevent decreases in blood pressure. The recommended maximum dose of the local anesthetic should not be exceeded. Injection should be made slowly and with frequent aspiration. Allow a five-minute interval between sides.
Fetal/Neonatal Adverse Reactions
There have been reports of fetal and neonatal deaths associated with administration of mepivacaine for paracervical and/or pudendal nerve blocks in pregnant women during delivery. Adhere to recommended dosages and proper administration techniques for these blocks. There have also been reports of fetal bradycardia, neonatal respiratory depression, and neonatal seizures after maternal administration of mepivacaine during delivery. Inadvertent direct injection into the fetus at delivery with serious outcomes, including death, have been described. The fetal heart rate should be monitored continuously, and electronic fetal monitoring is highly advisable.
Failure to achieve adequate analgesia with recommended doses should arouse suspicion of intravascular or fetal intracranial injection.
The use of some local anesthetic drug products during labor and delivery may be followed by diminished muscle strength and tone for the first day or two of life. The long-term significance of these observations is unknown.
8.6 Hepatic Impairment
Amide-type local anesthetics, such as mepivacaine, are metabolized by the liver. Patients with severe hepatic impairment, because of their inability to metabolize local anesthetics normally, are at a greater risk of developing toxic plasma concentrations, and potentially local anesthetic systemic toxicity. Therefore, consider reduced dosing and increased monitoring for local anesthetic systemic toxicity in patients with moderate to severe hepatic impairment treated with CARBOCAINE, especially with repeat doses [see Warnings and Precautions (5.6), Use in Specific Populations (8.5), Clinical Pharmacology (12.3)].