Physical incompatibility of sodium bicarbonate, amiodarone, dextromethorphan, and memantine tablets coadministered via a nasogastric tube: A case report

Abstract

Introduction: Coadministration of multiple oral medications through a nasogastric (NG) tube can lead to unexpected physical incompatibilities that compromise drug delivery and patient safety. This case report describes recurrent NG tube obstruction following the simultaneous administration of sodium bicarbonate, amiodarone, dextromethorphan, and memantine tablets, highlighting a preventable yet clinically significant interaction. Discussion: The combination produced a viscous, resin-like precipitate that repeatedly clogged the NG tube and necessitated tube replacement. A bedside, semi-qualitative simulation experiment reproduced the same phenomenon, with precipitate formation occurring shortly after mixing, suggesting a pH-dependent conversion of amiodarone hydrochloride to its poorly soluble free-base form in the presence of sodium bicarbonate. This finding emphasizes the potential for physical incompatibilities between alkaline agents and weakly basic drugs during enteral medication preparation and administration. Simple pre-administration compatibility testing may help clinicians and caregivers identify such risks and prevent complications. Conclusion: This case underscores the importance of evaluating the physical compatibility of crushed or dispersed medications prior to enteral administration, particularly in patients with polypharmacy. Increased awareness and individualized preparation strategies can reduce the risk of tube obstruction and ensure safe and effective drug delivery via NG tubes.