Compatibility of medications with enteral feedings

Administration of medications to patients with nasogastric tubes has traditionally been done in a bolus fashion. An alternative to this would be to mix the medications in the continuous drip enteral feeding with subsequent continuous administration. The purpose of this study was to determine the compatibility of select medications with Ensure, Ensure Plus, and Osmolite. We observed neither visible abnormalities in the mixtures nor change in pH of the enteral products after the addition of digoxin, theophylline, phenytoin, methyldopa, or furosemide. The addition of theophylline to all three enteral products caused a substantial increase in the osmolality. We also examined the concentrations of the mixtures to detect any changes occurring over the 12-hr infusion time. A wide variation in concentrations after the addition of phenytoin suspension was corrected by adding the injectable form to the enteral products. Digoxin and furosemide concentrations were essentially unchanged; however, the methyldopa concentration decreased up to 23% over the 12-hr study period. We, therefore, cannot recommend the addition of theophylline, phenytoin suspension, or methyldopa to the three enteral products tested.