| Summary: | Background: Anti-epileptic drugs are known to be the risk of teratogenicity. Topiramate (TPM) is a new kind of
such drug, for which no research has confirmed the incidence of producing congenital abnormalities.
Objective: This study was conducted to study the teratogenic effects of TPM by using chick embryos as an animal
model and the results can be compared to the human embryo of the same stage.
Methods: Fertilized Leghorn hen eggs were injected in ovo with two concentrations of TPM, which were 10mg,
and 20mg, in NSS at a volume of 0.1 ml into the yolk sac at 21 hrs of incubation and repeated injections at 72 hrs
at a volume of 0.05 ml. The chick embryos on day 3, 6 and 11 of incubation were sacrificed and all living embryos
were processed for total mount and serial section.
Results: The mortality rate increased corresponding to the concentrations of TPM, and the embryonic stage. The
total mount of day 3 showed major abnormalities of the eye and heart, such as microphthalmia and looser of
heart looping. The serial section of day 3 showed opening of the anterior neuropore, ectopia viscerae and multiple
malformations of the eye and heart. Day 6 chick embryos showed ectopia cordis and ectopia viscerae. Moreover,
there were retardation and abnormalities of several organs such as eye, heart, liver, mesonephros and gonads. Day
11 chick embryos showed ectopia viscerae and several growth retardations, retardation of ossification of both limb
bones and skull bones.
Conclusion: This study showed that TPM might cause embryonic death, growth retardation and abnormalities
of the eye, heart, an opening of the anterior neuropore and ectopia viscerae. This might indicate abnormalities to
the baby born from mother with gestational epilepsy who was taking this drug continuously, and it might lead to
spontaneous abortion or congenital anomalies of the fetus.
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