Phenytoin malabsorption after jejunostomy tube delivery.

The literature supports interactions between phenytoin and both enteral feeding products and nasogastric feeding tubes; however, no published reports exist regarding the interaction of phenytoin with jejunostomy feedings. A 29-year-old woman with cerebral palsy, mental retardation, and a history of seizures was treated with intravenous phenytoin, which yielded detectable therapeutic serum concentrations. After switching to a comparable phenytoin suspension administered by jejunostomy tube, her serum phenytoin concentrations fell to below assay sensitivity concentrations. This drop, nearly 100%, was the greatest that we found reported in the literature. Distal placement of the jejunostomy tube within the small bowel may augment potential phenytoin-tube-enteral product interactions. In addition, the possible decrease in gastrointestinal transit time because of anatomic placement may not allow for adequate drug absorption. Decreased phenytoin bioavailability may become more common with increased use of supplemental feeding tubes.