Optimizing Therapeutic Drug Monitoring in Pregnant Women: A Critical Literature Review

BACKGROUND

More than 90% of pregnant women take at least one drug during pregnancy. Drug dose adjustments during pregnancy are sometimes necessary due to various pregnancy-induced physiological alterations frequently associated with lower plasma concentrations. However, the clinical relevance or benefits of therapeutic drug monitoring (TDM) in pregnant women have not been specifically studied. Clinical pharmacokinetic studies in pregnant women are incredibly challenging for many reasons. Despite this, regulatory agencies have made efforts to encourage the inclusion of this population in clinical trials to achieve more information on the pharmacotherapy of pregnant women. This review aims to provide support for TDM recommendations and dose adjustments in pregnant women.

METHODS

The search was conducted after a predetermined strategy on PubMed and Scopus databases using the MeSH term "pregnancy" alongside other terms such as "Pregnancy and dose adjustment," "Pregnancy and therapeutic drug monitoring," "Pregnancy and PBPK," "Pregnancy and pharmacokinetics," and "Pregnancy and physiological changes."

RESULTS

The main information on TDM in pregnant women is available for antiepileptics, antipsychotics, antidepressants, antibiotics, antimalarials, and oncologic and immunosuppressive drugs.

CONCLUSIONS

More data are needed to support informed benefit-risk decision making for the administration of drugs to pregnant women. TDM and/or pharmacokinetic studies could ensure that pregnant women receive an adequate dosage of an active drug. Mechanistic modeling approaches potentially could increase our knowledge about the pharmacotherapy of this special population, and they could be used to better design dosage regimens.

Metastatic colorectal cancer during pregnancy: A tertiary center experience and review of the literature

Background

Colorectal cancer during pregnancy is rare. Diagnosis may be delayed and clinicians are faced with unique challenges when formulating management plans, having to consider the well-being of both fetus and mother.

Cases

Our series outlines five cases of metastatic colorectal cancer during pregnancy. There was one patient who presented in each of the first, second and third trimesters, whilst the remaining were post-partum. Diagnosis was difficult as the patients were either asymptomatic or their symptoms were misconstrued as features of pregnancy. Two patients received chemotherapy while pregnant but only one had a successful delivery. Survival of patients in this series ranged between 1 and 35 months from diagnosis.

Conclusion

Women with gestational colorectal cancer are often diagnosed at an advanced stage and have a poor prognosis.

Cancer in pregnancy: safety and efficacy of systemic therapies

PURPOSE OF REVIEW

Cancer in pregnancy has become increasingly frequent. It has become clear that for specific cancers under well defined circumstances, oncological treatment in pregnancy can be well tolerated and feasible for both mother and fetus. Continued critical assessment of the available literature and registration of cancer in pregnancy cases and outcomes for mother and child are necessary to work toward implementing optimal cancer treatment during pregnancy.

RECENT FINDINGS

Physiologic changes in pregnancy may alter distribution and efficacy of systemic therapy. Data on systemic therapy including, chemotherapy, hormonal therapy, and targeted therapy during pregnancy are available but incomplete. Outcomes of fetuses exposed to chemotherapy in utero are generally reassuring, but new targeted therapies are mostly discouraged in pregnancy.

SUMMARY

Cancer treatment during pregnancy is possible, depending on type and timing of systemic therapy and treatment modality. Available data are reassuring with a modest increase in complications such as growth restriction and preterm birth. The effect of new targeted therapies is often still unclear and therefore discouraged.

[Tyrosine kinase inhibitors and pregnancy: A risk to the fetus?]

The association of cancer and pregnancy is increasingly frequent. This is related, partially, to the increasingly belated age of pregnancy. The management of cancer in pregnancy is a complicated issue. The use of tyrosine kinase inhibitors (TKIs) during pregnancy remains rare and only few data are available concerning their transplacental passage. The aim of this work is to review the data described in the literature, in order to highlight the risks incurred by the fetus, associated with these TKIs' treatment. Up to 189 pregnancies of women treated with TKIs during part or throughout their pregnancy have been described. Clinical data are reassuring and would be in favor of taking the treatment in terms of the balance maternal profit versus fetal risk. These data must, nevertheless, be interpreted with caution.

Variation in transplacental transfer of tyrosine kinase inhibitors in the human perfused cotyledon model

BACKGROUND

The use of tyrosine kinase inhibitors (TKis) during pregnancy in humans remains rare, and little data are available on their transplacental passage. Erlotinib and gefitinib are the first-line targeted therapy in case of stage IV nonsmall-cell lung cancer with an EGFR-activating mutation. There are no data available regarding the comparative use of these TKis in pregnant patients. We aimed to compare the transplacental transfer of gefitinib, imatinib and erlotinib, using the ex vivo method of human perfused cotyledon, and to determine the placental accumulation of TKis.

MATERIALS AND METHODS

Term placentas were perfused after delivery with gefitinib, imatinib and erlotinib at targeted maternal concentrations around the steady-state plasma trough concentration (i.e. 500, 1000 and 1500 ng/ml, respectively). Samples from fetal and maternal circulations were collected in order to monitor TKis concentrations. Main transfer parameters such as fetal transfer rate (FTR), clearance index (CI) and placental uptake were assessed.

RESULTS

Mean FTR of gefitinib, imatinib and erlotinib were 16.8%, 10.6% and 31.4%, respectively. Mean CI of gefitinib, imatinib and erlotinib were 0.59, 0.48 and 0.93, respectively. Placental uptake in cotyledon was 0.030% %, 0.010% and 0.003% for gefitinib, imatinib and erlotinib, respectively, corresponding to a mean mass of 27.7 µg for gefitinib, 15.7 µg for imatinib and 6.8 µg for erlotinib.

CONCLUSION

The results suggest that TKis cross the placenta at therapeutic level. Particularly, erlotinib crosses the placenta at a higher rate than gefitinib or imatinib. All of them have a very low placental uptake. These data may suggest that gefitinib should be preferred to erlotinib for the treatment of pregnant woman with lung cancer harboring an EGFR-activating mutation, during the second and third trimesters of pregnancy.