BackgroundWomen are commonly prescribed a variety of medications during pregnancy. As most organ systems are affected by the substantial anatomical and physiological changes that occur during pregnancy, it is expected that pharmacokinetics (PK) (absorption, distribution, metabolism, and excretion of drugs) would also be affected in ways that may necessitate changes in dosing schedules. The objective of this study was to systematically identify existing clinically relevant evidence on PK changes during pregnancy.Methods and FindingsSystematic searches were conducted in MEDLINE (Ovid), Embase (Ovid), Cochrane Central Register of Controlled Trials (Ovid), and Web of Science (Thomson Reuters), from database inception to August 31, 2015. An update of the search from September 1, 2015, to May 20, 2016, was performed, and relevant data were added to the present review. No language or date restrictions were applied. All publications of clinical PK studies involving a group of pregnant women with a comparison to nonpregnant participants or nonpregnant population data were eligible to be included in this review. A total of 198 studies involving 121 different medications fulfilled the inclusion criteria. In these studies, commonly investigated drug classes included antiretrovirals (54 studies), antiepileptic drugs (27 studies), antibiotics (23 studies), antimalarial drugs (22 studies), and cardiovascular drugs (17 studies). Overall, pregnancy-associated changes in PK parameters were often observed as consistent findings among many studies, particularly enhanced drug elimination and decreased exposure to total drugs (bound and unbound to plasma proteins) at a given dose. However, associated alterations in clinical responses and outcomes, or lack thereof, remain largely unknown.ConclusionThis systematic review of pregnancy-associated PK changes identifies a significant gap between the accumulating knowledge of PK changes in pregnant women and our understanding of their clinical impact for both mother and fetus. It is essential for clinicians to be aware of these unique pregnancy-related changes in PK, and to critically examine their clinical implications.

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Pediatric drug research is gradually becoming more and more accepted as the norm for assessing whether a drug is safe and efficacious for infants and children. The process of informed consent and assent for these trials presents a major challenge. The aim of this review is to map historical, ethical and legal aspects relevant to the challenges of informed consent in the setting of pediatric drug research. The impact of age, level of maturity and life circumstances on the process of obtaining informed consent as well as the relations between consent and assent are discussed. There appears to be a lack of regulatory clarity in the area of pediatric clinical trials; while numerous statements have been made regarding children's rights to autonomy and their ability to care for themselves and for younger ones, the ever changing status of adolescence is still difficult to translate to informed consent. This may delay scientific and clinical advancement for children who are at the very junction of being independent and not needing parental permission. Obtaining consent and assent for pediatric clinical trials is a delicate matter, as both parent and child need to agree to participate. The appropriate transfer of information to guardians and the children, especially concerning potential risks and benefits, is at the heart of informed consent, as it serves to protect both patient and physician. As many adults lack health literacy, one must ensure that guardians receive relevant information at a level and in forms they can understand regarding the trials their children are asked to participate in. Key PointsThe appropriate transfer of information to guardians and the children, especially concerning potential risks and benefits, is at the heart of informed consent, as it serves to protect both patient and physician.There is compelling evidence that most children younger than 9 years of age lack the capacity to consent for participation in clinical trials.In some jurisdictions, institutional review boards approve the participation in drug research of healthy volunteering children during early adolescence.