Fetal Exposure to 3,4-Diaminopyridine in a Pregnant Woman with Congenital Myasthenia Syndrome

Objective: To report a case of fetal exposure to pyridostigmine and 3,4-diaminopyridine (3,4-DAP) in a pregnant woman with congenital myasthenia syndrome (CMS). Case Summary: A 31-year-old woman with postsynaptic CMS, not genetically characterized, was being treated with pyridostigmine and 3,4-DAP. She decided to become pregnant, despite having been informed about the paucity of available information on the possible risks of these drugs for the fetus. The dose of pyridostigmine remained stable throughout the pregnancy (60 mg every 8 h), and the 3,4-DAP dose was adjusted according to the patient's level of fatigue (20 mg/day, with occasional additional doses of 5 mg). At 25 weeks' gestation, ultrasonography confirmed the presence of only one umbilical artery. The results of other tests were normal. At 38 weeks' gestation, a healthy male neonate was born. His APGAR scores were 9 and 10 at 1 and 5 minutes, respectively. Five months later, the infant was healthy and his pediatric progress had been uneventful. Discussion: It was difficult to find information about the possible congenital defects related to the use of 3,4-DAP because it is a rarely used drug. This case attracted our interest because it is an uncommon disease, and we found no reports on the use of 3,4-DAP during pregnancy. To our knowledge, as of this writing, this is the first published report of the use of 3,4-DAP during pregnancy. Conclusions: A successful pregnancy with a healthy infant was achieved after fetal exposure to 3,4-DAP and pyridostigmine.