Pregnancy outcome after in utero exposure to valproate : evidence of dose relationship in teratogenic effect

Lithium in pregnancy: the need to treat, the duty to ensure safety

INTRODUCTION

Untreated bipolar disorder during pregnancy leads to detrimental repercussions on the mother-infant pair's health. Despite different drugs having been proposed as mood stabilizers, lithium remains the first-choice agent for preventing mood changes.

AREAS COVERED

Analyzing up-to-date information on the reproductive safety of lithium and providing practice guidelines to optimize its use during pregnancy.

EXPERT OPINION

Findings from prospective and case-control studies confirm an increased, specific risk of Ebstein's anomaly (4.45-7.6/1000 live births), although lower than that previously reported. A potential increase in the risk of neural tube defects should also be taken into consideration. Moreover, several perinatal complications may occur, and even in the presence of relatively low infant serum levels, in the case of drug exposure during late pregnancy. Despite such concerns, lithium should still be considered the first-choice agent for treating bipolar disorder in pregnancy. Indeed, the U.S. FDA recently issued a new warning regarding the reproductive safety of antipsychotics. Moreover, the risk of fetal valproate/carbamazepine syndrome (and the confirmed neurodevelopmental teratogenicity of valproate) contraindicates the use of both medications, whereas the use of lamotrigine is limited by efficacy concerns. However, women who need lithium treatment during pregnancy should be carefully monitored: a strict gynecologic and psychiatric surveillance and, probably, preconception folate supplementation is highly advisable. Moreover, delivery should be programmed in Neonatal Intensive Care Units to ensure optimal management of potential iatrogenic perinatal complications.

Synaptic and intrinsic balancing during postnatal development in rat pups exposed to valproic acid in utero

Valproic acid (VPA) is among the most teratogenic of commonly prescribed anticonvulsants, increasing the risk in humans of major malformations and impaired cognitive development. Likewise, rats exposed prenatally to VPA exhibit a variety of neuroanatomical and behavioral abnormalities. Previous work has shown that pyramidal neuron physiology in young VPA-exposed animals is marked by two strong abnormalities: an impairment in intrinsic neuronal excitability and an increase in NMDA synaptic currents. In this study, we investigated these abnormalities across postnatal development using whole-cell patch recordings from layer 2/3 neurons of medial prefrontal cortex. We found that both abnormalities were at a peak soon after birth but were gradually corrected as animals matured, to the extent that normal excitability and NMDA currents had been restored by early adolescence. The manner in which this correction happened suggested coordination between the two processes. Using computational models fitted to the physiological data, we argue that the two abnormalities trade off against each other, with the effects on network activity of the one balancing the effects of the other. This may constitute part of the nervous system's homeostatic response to teratogenic insult: an attempt to maintain stability despite a strong challenge.

Drug treatment for mood disorders in pregnancy

PURPOSE OF REVIEW

During the last few years, several researches, often showing contradictory findings, have investigated the safety of psychotropic medications used for treating mood disorders in pregnancy. Hence, the necessity exists to update this information constantly in order to ensure the safest option for the mother-infant pair.

RECENT FINDINGS

The risk of fetal anomalies associated with early in-utero exposure to antidepressants seems to be increased after paroxetine and clorimipramine exposure, whereas prenatal exposure to nearly all antidepressants is linked to the potential onset of the Prenatal Antidepressant Exposure Syndrome. As regards classic mood stabilizers, the teratogenic risk historically reported with lithium should probably be softened, whereas valproate is the medication which shows the strongest association with fetal anomalies. An increased risk of autism-spectrum disorders and infant neurodevelopmental delay is also associated with valproate exposure through the placenta. No significant reproductive safety data are available on atypical antipsychotics, although such medications may indirectly increase the rate of fetal malformation by inducing gestational diabetes.

SUMMARY

Avoiding the use of clorimipramine, paroxetine, valproate, and atypical antipsychotics during pregnancy is advisable. However, when starting or continuing pharmacological treatment during pregnancy, clinicians should consider not only the intrinsic iatrogenic risk of birth defects or perinatal complications, but also the general safety profile for the expectant mother. Indeed, specific adverse reactions (such as nausea, vomiting, constipation, and excessive weight gain) may aggravate the classic clinical findings of pregnancy, thus indirectly facilitating the occurrence of pregnancy complications and fetal and neonatal problems.

Pregnancy outcome, thyroid dysfunction and fetal goitre after in utero exposure to propylthiouracil: a controlled cohort study

AIMS

Propylthiouracil (PTU) is presently considered to be the treatment of choice for hyperthyroidism in pregnancy. It is known to cross the human placenta, and therefore may affect the fetus. The major aims of this study were to evaluate the rate of major anomalies and to report the rate of fetal goitre, accompanied by hypothyroidism, in fetuses/ newborns of mothers after in utero exposure to PTU.

METHODS

Prospective observational controlled cohort study of PTU-exposed pregnancies of women counselled by the Israeli Teratology Information Service between the years 1994 and 2004 compared with women exposed to nonteratogens.

RESULTS

We followed up 115 PTU-exposed pregnancies and 1141 controls. The rate of major anomalies was comparable between the groups [PTU 1/80 (1.3%), control 34/1066 (3.2%), P= 0.507]. Hypothyroidism was found in 9.5% of fetuses/neonates (56.8% of whom with goitre). Hyperthyroidism, possibly resulting from maternal disease, was found in 10.3%. Goitres prenatally diagnosed by ultrasound were successfully treated in utero by maternal dose adjustment. In most cases neonatal thyroid functions normalized during the first month of life without any treatment. Median neonatal birth weight was lower [PTU 3145 g (2655-3537) vs. control 3300 g (2968-3600), P= 0.018].

CONCLUSIONS

PTU does not seem to be a major human teratogen. However, it could cause fetal/neonatal hypothyroidism with or without goitre. Fetal thyroid size monitoring and neonatal thyroid function tests are important for appropriate prevention and treatment.

Long-term efficacy of valproate versus lamotrigine in treatment of idiopathic generalized epilepsies in children and adolescents

PURPOSE

In order to estimate and compare the long-term effectiveness of lamotrigine (LTG) versus valproate (VPA) monotherapy in treatment of newly diagnosed idiopathic generalized epilepsies (IGE) the following study was performed.

METHODS

Medical records of 214 children and adolescents suffering from IGE were analyzed. 132 of them were on VPA monotherapy, 82 on LTG. The majority of patients had juvenile myoclonic epilepsy - 98, the rest: juvenile absence epilepsy - 32, childhood absence epilepsy - 53 and epilepsy with a tonic-clonic seizures on awakening - 12, others - 19. Mean age of the patients was 8.9 years (range 4-16 years). The mean time of treatment was 28 months, time of observation 40 months. In order to estimate retention rates and factors predicting successful treatment with LTG and VPA we used Kapplan-Meyer analysis and Gehan tests.

RESULTS

Data analysis showed significantly longer retention rates with VPA versus LTG treatment in overall rates as well in all syndromes subgroups. After 12 months of therapy 69% stayed on LTG therapy versus 89% on VPA, after 24 months 57% versus 83% respectively. VPA showed comparable efficacy in all IGE syndromes where LTG showed better efficacy in childhood and juvenile absence epilepsy than in juvenile myoclonic epilepsy. The shorter duration of treatment with LTG was due to lack of efficacy.

CONCLUSIONS

Our results show the superiority of VPA versus LTG treatment in idiopathic generalized epilepsy syndromes.

Topiramate in pregnancy and breastfeeding

Recent information suggests that use of the antiepileptic drug topiramate in pregnancy may raise some concerns, especially if used in polytherapy. Moreover, data on the safety of this antiepileptic drug for the breastfed infant are very limited. However, use of topiramate may be unavoidable in women who wish to become pregnant but who have already experienced severe adverse reactions to antiepileptic medications considered relatively safe in this female condition. Hence, we describe the healthy outcome of a male infant exposed to topiramate through the placenta and maternal milk and who was conceived while the mother was undergoing folic acid supplementation.