Lithium is used as a first-line treatment for bipolar disorder during perinatal period. Dosing of lithium can be challenging as a result of pharmacokinetic changes in renal physiology. Frequent monitoring of lithium blood levels during pregnancy is recommended in order remain within the therapeutic window (0.5 to 1.2 mEq/L). Lower neonatal lithium blood level (<0.64 mEq/L) at time of delivery reduces the risk of lithium side effects in the neonate.

The aim of the present study was to quantify the rate of lithium placental passage in real word.

We included a total of 68 mother-infant pairs for which a lithium measurement was performed intrapartum. Lithium serum concentrations were determined by means of an AVL 9180 electrolyte analyzer. The limit of quantification (LoQ) was 0.20 mEq/L and detection limit was 0.10 mEq/L. Pearson analyse was performer to assess the correlation between mother and umbilical cord lithium serum concentrations.

The mean of umbilical cord serum concentration at delivery was 0.57 mEq/L (SD=0.26, range 0,20-1,42). The mean infant-mother lithium ratio at delivery for the 68 pairs was 1.12 (SD=0.24) across a wide range of maternal concentrations (range 0.14-1,40 mEq/L). There was a strong positive correlation between maternal and umbilical cord lithium blood levels (Peearson correlation coefficient 0.948, p<0.001).

Lithium demostrates complete placental passage. This finding is consistent with the results of others studies (Newport 2005; Molenaar 2021).

No significant relationships.

Clozapine is an effective second-generation antipsychotic that is approved for treatment-resistant schizophrenia and risk reduction of recurrent suicidal behavior in schizophrenia or schizoaffective disorder. Its available pregnancy pharmacikinetics data remain limited, which presents a challenge for clinicians managing women taking clozapine during perinatal period .

The aim of this study was to provide new data of clozapine and norclozapine placental passage and neonatal outcomes.

We retrospectively studied a consecutive case series of six pregnancies where there was clozapine exposure (5 in politherapy and 1 in monotherapy). Clozapine and norclozapine serum concentrations were determined in the mother-infant pairs on the day of delivery (intrapartum maternal blood and umbilical cord blood respectively) and measured using a validated high-performance liquid chromatography method. The within- and between-day precision expressed as the coefficient of variation (CV)% were both <10%. The limit of quantification (LoQ) was 5 ng/mL. Neonatal outcomes were reviewed from pediatric records.

The mean infant-mother clozapine and norclozapine ratio at delivery were 0.44 (SD=0.13) and 0.28 (SD=0.05) respectively. There was a weak positive correlation between maternal and umbilical cord clozapine and norclozapine serum concentratios (Pearson correlation coefficient 0.183, p=0.769 and 0.827, p=0.084 respectively). The rate of neonatal complications was 16%. One neonate (16%) , whose mother had drug abuse history during pregnancy, presented with a generalized neurodevelopment delay and the consequent need for continuous intensive care.

In our study, placental passage of clozapine and norclozapine was partial during delivery. Statistical power was limited for examining te association between neonatal clozapine levels and neonatal outcomes.

No significant relationships.