Malformations following methimazole exposure in utero: an open issue.
BACKGROUND
In hyperthyroidism-complicated pregnancies, medical therapy is necessary to reach an euthyroid condition, and propylthiouracil (PTU) or methimazole (MMI) are used. These drugs are equally effective, but may cause fetal and neonatal hypothyroidism because they freely cross the placenta. Although PTU has not been significantly associated with embryo-fetal anomalies, it has been suggested that MMI might be responsible for a specific embryopathy.


METHODS
Two cases of major congenital anomalies after MMI exposure during pregnancy are reported.


CONCLUSIONS
PTU should be the drug of choice, and the use of MMI should be restricted to cases with allergic reactions, intolerance, or poor response to PTU.
Ferraris
Silvio
S
Dipartimento di Scienze Pediatriche, Università di Torino, Turin, Italy.
Valenzise
Mariella
M
Lerone
Margherita
M
Divizia
Maria Teresa
MT
Rosaia
Lucia
L
Blaid
Dario
D
Nemelka
Odette
O
Ferrero
Giovanni Battista
GB
Silengo
Margherita
M
D000014:Abnormalities, Drug-Induced / Q000209:etiology*; D013956:Antithyroid Agents / Q000627:therapeutic use*; D004476:Ectodermal Dysplasia / Q000209:etiology*; D005260:Female; D006801:Humans; D006980:Hyperthyroidism / Q000188:drug therapy*; D007231:Infant, Newborn; D008297:Male; D008423:Maternal Age; D008713:Methimazole / Q000627:therapeutic use*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000188:drug therapy*; D018566:Pregnancy, High-Risk; D012535:Scalp / Q000002:abnormalities; D014427:Twins
D013956:Antithyroid Agents; D008713:Methimazole