Characterization of neonatal and infant enterostomy fluids

The composition of gastrointestinal (GI) fluids is crucial for the dissolution, solubilization, and absorption of orally administered drugs. Disease- or age-related changes in GI fluid composition could significantly affect the pharmacokinetics of oral drugs. However, limited studies have been conducted on the characteristics of GI fluids in neonates and infants due to practical and ethical challenges. The current study collected enterostomy fluids from 21 neonate and infant patients over an extended period of time and from different regions of the small intestine and colon. The fluids were characterized for pH, buffer capacity, osmolality, total protein, bile salts, phospholipids, cholesterol, and lipid digestion products. The study found a large variability in the fluid characteristics among the different patients, in line with the highly heterogeneous study population. Compared to adult intestinal fluids, the enterostomy fluids from neonates and infants had low bile salt concentrations, with an increasing trend as a function of age; no secondary bile salts were detected. In contrast, total protein and lipid concentrations were relatively high, even in the distal small intestine. These findings suggest marked differences in intestinal fluid composition between neonates and infants versus adults, which may affect the absorption of certain drugs.