Pyridostigmine is a reversible cholinesterase inhibitor used in the treatment of myasthenia gravis (MG), paralytic ileus, and post-operative urinary retention. Pyridostigmine is also included in Nerve Agent Pre-treatment Sets (NAPS) issued to military personnel.
Available data on pyridostigmine exposure in human pregnancy are limited to case reports/series describing the treatment of MG. Transient neonatal myasthenia gravis (TNMG) and arthrogryposis multiplex congenita (AMC) are recognised neonatal complications of maternal MG and are attributed to the transplacental transfer of maternal antibodies to acetylcholine (ACh) receptors. The published data therefore focus primarily on the link between maternal MG and these two fetal conditions, and not on the teratogenic potential of pyridostigmine.
The very limited published data do not suggest that pyridostigmine is a major teratogen, although one case report has suggested a potential effect of high dose (supratherapeutic) pyridostigmine (>40mg/kg/day, standard dose <10mg/kg/day) on fetal brain development. Data relating to other adverse pregnancy outcomes are too limited to facilitate a robust evidence-based assessment of risk, and although increased risks are not suggested by the available data, pregnant women being prescribed pyridostigmine should be made aware of the data limitations.
Inadvertent exposure to pyridostigmine at any stage of pregnancy would not usually be regarded as medical grounds for termination of pregnancy. Enhanced antenatal surveillance may be warranted and should be decided on a case-by-case basis. Other risk factors may also be present in individual cases which may independently increase the risk of adverse pregnancy outcome. Clinicians are reminded of the importance of consideration of such factors when performing case-specific risk assessments. Discussion with UKTIS is recommended in all cases of exposure to pyridostigmine at any stage of pregnancy.
Where treatment with pyridostigmine is clinically indicated it should not be withheld because of pregnancy. International consensus guidelines state that oral pyridostigmine is recommended as the first line treatment for MG. MG in pregnancy may be associated with a greater risk of maternal respiratory failure and transient neonatal MG, therefore management by a multidisciplinary team is recommended.
This is a summary of the full UKTIS monograph for health care professionals and should not be used in isolation. The full UKTIS monograph and access to any hyperlinked related documents is available to NHS health care professionals who are logged in.
If you have a patient with exposure to a drug or chemical and require assistance in making a patient-specific risk assessment, please telephone UKTIS on 0344 892 0909 to discuss the case with a teratology specialist.
If you would like to report a pregnancy to UKTIS please click here to download our pregnancy reporting form. Please encourage all women to complete an online reporting form.