Dose recovery after repeated drug administration via nasogastric feeding tubes under clinically relevant conditions: a novel in vitro model.

Administration of solid oral drug products via enteral feeding tubes (EFTs) is common due to the lack of suitable alternatives but is associated with substantial risk of drug loss. A novel in vitro setup was developed to simulate clinical administration, considering patient supine positioning, tube temperature control, tube diameter and material, and nutritional formula supply. Drug recovery of furosemide and levothyroxine was evaluated under best- and worst-case administration conditions over several days. Under best case conditions, including multiple syringe and tube flushing steps, recovery exceeded 90 percent for both drugs. Under worst-case conditions, where flushing was omitted, furosemide recovery on day one reached approximately 90 percent in 14 French tubes and 70 percent in 10 French tubes, while levothyroxine recovery was around 80 percent across all tubes. Drug recovery in 14 French tubes declined over time, reflecting sedimentation, incomplete syringe emptying, and interactions with nutritional formula. During nutritional supply, agglutination of nutrient formula and increased back pressure occurred, and residual deposits and bacterial colonization were observed at the tube interior. These findings underscore the critical role of flushing syringes and EFTs to maximize dose recovery and prevent tube obstruction. The study demonstrates that clinically relevant administration factors including tube diameter, duration of nutrition, and procedural adherence substantially influence delivered drug doses. The presented in vitro model provides a standardized, practice-oriented platform for evaluating drug recovery through EFTs, supporting optimization of clinical administration protocols and guiding future recommendations.