A thorough knowledge of the newborn (age, birth to 1 month postpartum) infant's gastrointestinal tract (GIT) is critical to the evaluation of the absorption, distribution, metabolism, and excretion (ADME) of orally administered drugs in this population. Developmental changes in the GIT during the newborn period are important for nutrient uptake as well as the disposition of orally administered medications. Some aspects of gastrointestinal function do not mature until driven by increased dietary complexity and nutritional demands later in the postnatal period. The functionalities present at birth, and subsequent maturation, can also impact the ADME parameters of orally administered compounds. This review will examine some specific contributors to the ADME processes in human neonates, as well as what is currently understood about the drivers for their maturation. Key species differences will be highlighted, with a focus on laboratory animals used in juvenile toxicity studies. Because of the gaps and inconsistencies in our knowledge, we will also highlight areas where additional study is warranted to better inform the appropriate use of medicines specifically intended for neonates.
The US Food and Drug Administration (FDA) Division of Food Contact Notifications (DFCN) performs infant lifestagespecific exposure and safety assessments during the premarket review of FCNs proposed for use with infant formula or human milk. DFCN previously identified two protocols that may be best suited to support infant safety: the multigenerational developmental and reproductive toxicology (Gen-DART) protocol and the juvenile animal study (JAS) protocol. The Gen-DART protocol tests chemical exposure from prior to mating through one or two generations in rodents, while JAS protocols test a chemical during a specific developmental window. At FDA, Gen-DART studies are currently recommended to support the safety of food additives (FAs), including food contact substances, across lifestages (from conception through adulthood). JAS protocols are recommended in the nonclinical safety assessment of drugs seeking pediatric indications. To improve our recommendations regarding the use of either Gen-DART or JAS protocols for the infant safety assessment of food contact materials, we created a database of FDA-reviewed Gen-DART or JAS. Our database contains information from 41 Gen-DART studies (38 FAs) and 51 JAS (29 drugs). Both protocols can detect toxicity relevant to infant safety assessment, such as developmental toxicity in neurological, endocrine, reproductive, immunological, or skeletal systems. Selection of either protocol will depend on the amount of information available for the chemical under study. The Gen-DART protocol may be preferred when limited data on the mode of action or target organ of the chemical are available. However, if these data are available, a JAS may provide the best assessment of potential juvenile toxicity.
The Food Contact Notification (FCN) programme was authorised by the US Food and Drug Administration (USFDA) Modernization Act of 1997. Manufacturers may file FCNs for food contact substances (FCSs) not already authorised or pre-sanctioned by the USFDA by demonstrating a reasonable certainty of no harm for their intended uses. The Division of Food Contact Notifications (DFCN) 10-year Retrospective Assessment Group was formed to collect and develop metrics associated with the first decade of the FCN Programme and determine the extent selected aspects of the review process contributed to the effective FCN. Comparative analysis of 924 FCNs revealed that 76% become effective, 23% were withdrawn and 1% received a not accepted status. The focus of the Group was to identify factors impacting the likelihood of an FCN becoming effective.
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