Importance of TDM During Pregnancy and Breastfeeding

Abstract

Therapeutic drug monitoring (TDM) is specific method of clinical pharmacology for monitoring of the therapy using measurement of drugs serum concentrations followed by interpretation and good cooperation with clinicians. Almost every pregnant woman is exposed to some type of medication during pregnancy. It was found a significant correlation between teratogenic effects and maternal or umbilical cord concentrations of some drugs, but not dose. For this reason, TDM in mother during pregnancy is more valuable than the given dose for estimating and possibly obviating the teratogenic risk of these drugs on the fetus. However, the data relating to the transplacental passage for most of drugs remain sparse. It was reported that analytical models should also take into account not only type and dose, but also levels of drugs in the mother and the neonate at birth as a closer surrogate marker for fetal exposure. Measuring the umbilical cord/maternal serum drug level ratio at birth is the method recommended to assess transplacental transfer. The decline in plasma concentrations during pregnancy was also observed with a considerable interindividual variability in the effect of pregnancy on kinetics of some drugs. Therefore, frequent TDM during pregnancy and after delivery is necessary to optimize treatment in women taking these drugs in the period of instable kinetics. The data on the transfer of drugs to the milk and the risk of exposure to the breastfed infants remain also sparse and only a limited number of studies have actually measured the infant blood levels. It was reported that the monitoring of breastfed infant’s concentrations appears to be the most relevant method for analysis of drugs exposure in breastfed infants (especially in those with some clinical problems such as sedation, poor suckling, and life-threatening rashes), overriding any other calculation.