Medication Administration Through Enteral Feeding Tubes

Nancy Toedter Williams, Pharm.D., BCPS, BCNSP


Am J Health Syst Pharm. 2008;65(24):2347-2357. 

In This Article

Mixing Medications With EN Formulations, Flushing Enteral Feeding Catheters, and Diluting Liquid Medications

The addition of medication directly to the enteral formula should be avoided. Although it may be convenient to mix drugs with enteral feedings, this practice can result in physical incompatibilities, decreased drug absorption, increased risk of tube occlusions, and potential microbial contamination.[6,9,13] Additionally, if feedings are stopped, the amount of medication that was actually administered to the patient will not be known. A possible exception for mixing medications with feeding formulas involves the addition of liquid electrolytes, such as sodium or potassium, to the enteral preparation.[6,27]

Various medications may cause drug–formula incompatibilities and result in tube occlusions. For example, mixing certain acidic syrups and elixirs with enteral formulas may produce clumping or thickening because the acidic liquid preparations cause protein denaturation in the enteral formula. Formulas that have intact proteins are more affected than those that contain free amino acids or hydrolyzed protein.[10,19] To avoid these potential interactions and incompatibilities, medications should be given as a bolus and separated from EN, and feeding tubes should be flushed with 15–30 mL of water before and after medication administration. Smaller water flush volumes are recommended in children. When multiple medications are scheduled for administration at the same time, each should be given separately, and the feeding tube should be irrigated with 5–10 mL of water between each medication. When delivering any medication through an enteral access device, the appropriate flushing technique is essential to reduce the risk of tube occlusion and to maintain patency.[6,24,27] Flushes also ensure total drug delivery by rinsing the tubing after medication administration.

In addition to flushing enteral feeding catheters with water before and after drug delivery, diluting liquid medications, particularly those that are highly concentrated or viscous, is also important. This helps reduce the medication osmolality, prevent tube occlusions, and increase drug delivery rates. Various volumes of water have been suggested for drug dilution, which include 10–30 mL and up to 60–90 mL.[24]


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