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Mexiletine Pregnancy and Breastfeeding Warnings

Mexiletine is also known as: Mexitil

Medically reviewed by Last updated on Nov 1, 2021.

Mexiletine Pregnancy Warnings

Mexiletine has been assigned to pregnancy category C by the FDA. Animal studies have failed to reveal evidence of teratogenicity or impaired fertility, but increased fetal resorption has been observed following dosages up to four times the maximum recommended human dose (on a per kg basis). There are no controlled data in human pregnancy. Mexiletine should be given during pregnancy only when benefit outweighs risk.

There is a paucity of data on the use of mexiletine during human pregnancy. In the limited data available, there is no evidence of teratogenicity or fetotoxicity associated with mexiletine. Mexiletine crosses the human placenta. In the first case described below, the umbilical cord to maternal plasma mexiletine levels were each 0.3 mcg per mL.

Mexiletine 200 mg and propranolol 40 mg three times a day were given to a 34-year-old woman from gestation week 32 through delivery at week 39 for paroxysmal ventricular tachycardia. At delivery, the infant was structurally normal, but suffered bradycardia (90 beats per min), which was thought to be due to propranolol. The infant's heart rate spontaneously increased to normal.

No adverse effects on the fetus or newborn were noted after mexiletine 200 mg three times a day and propranolol or atenolol were administered to two pregnant women, one of whom was taking mexiletine throughout pregnancy, and one of whom received it from gestation week 14 on. The newborn whose mother had taken mexiletine throughout pregnancy developed a seizure disorder at eight months of age, but had not been breast-fed since age three months.

In general, due to the lack of experience with mexiletine during human pregnancy, complete safety information is unavailable.

See references

Mexiletine Breastfeeding Warnings

Limited data reveal that mexiletine typically concentrates in human milk. Paired milk and maternal serum mexiletine levels from a woman who was taking mexiletine 200 mg three times a day reveal a mean ratio of 1.5, with a peak milk concentration of 0.96 mcg per mL. In this report, as well as two others, no adverse effects on the nursing infant were observed.

Mexiletine is excreted into and concentrates in human milk. Limited data suggest that adverse effects in the nursing infant are unlikely. The manufacturer recommends an alternative method of infant feeding when mexiletine is considered necessary for the nursing woman. However, mexiletine is considered compatible with breast-feeding by the American Academy of Pediatrics.

See references

References for pregnancy information

  1. Lownes HE, Ives TJ "Mexiletine use in pregnancy and lactation." Am J Obstet Gynecol 157 (1987): 446-7
  2. Brodsky M, Doria R, Allen B, Sato D, Thomas G, Sada M "New-onset ventricular tachycardia during pregnancy." Am Heart J 123 (1992): 933-41
  3. Rotmensch HH, Rotmensch S, Elkayam U "Management of cardiac arrhythmias during pregnancy: current concepts." Drugs 33 (1987): 623-33
  4. Page RL "Treatment of arrhythmias during pregnancy." Am Heart J 130 (1995): 871-6
  5. "Product Information. Mexitil (mexiletine)." Boehringer-Ingelheim, Ridgefield, CT.
  6. Timmis AD, Jackson G, Holt DW "Mexiletine for control of ventricular dysrhythmias in pregnancy." Lancet 2 (1980): 647-8
  7. Tamari I, Eldar M, Rabinowitz B, Neufeld HN "Medical treatment of cardiovascular disorders during pregnancy." Am Heart J 104 (1982): 1357-63

References for breastfeeding information

  1. Lewis AM, Johnston A, Patel L, Turner P "Mexiletine in human blood and breast milk." Postgrad Med J 57 (1981): 546-7
  2. Committee on Drugs, 1992 to 1993 "The transfer of drugs and other chemicals into human milk." Pediatrics 93 (1994): 137-50
  3. "Product Information. Mexitil (mexiletine)." Boehringer-Ingelheim, Ridgefield, CT.
  4. Lownes HE, Ives TJ "Mexiletine use in pregnancy and lactation." Am J Obstet Gynecol 157 (1987): 446-7

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.