Don’t rush to crush
When patients have enteral feeding tubes in place it is often considered convenient to use the tube to give medications. However, co-administration of drugs in this way to patients receiving enteral nutrition can be problematic for several reasons. Manipulating the physical structure of medications (crushing, dissolving, diluting etc) to pass them down a tube can lead to physicochemical changes that can
a) alter the bioavailability, therapeutic effect and required dosage
b) lead to drug-nutrient and/or drug-drug incompatibility interactions
c) cause gastrointestinal symptoms and intolerance, and enteral feed wastage
d) cause tube blockage or binding of drugs to tube material
Additionally, crushing of pills can lead to dosage loss in pill crushing devices and during aerosolisation of medication powders.
The dietitian should be aware of the potential pitfalls of medication use and how these can be mitigated to enable rational practice in terms of medications delivered down feeding tubes. The input and collaboration of the hospital pharmacist can also be very valuable. Every effort should be made to make parenteral/IV (or alternatively sub-lingual/transdermal etc) drug formulations available where possible. Where oral formulations are the only option, liquid formulations, such as commercial syrups and suspensions, may be practically useful, but the general concerns about medications being delivered down feeding tubes may still apply.
As a general rule, medications should never be added in to the feed formula itself. The complex mixture of nutrients in enteral feeds increases the likelihood of drug-nutrient interactions, and changes in pH caused by medications can result in unabsorbable precipitants in the feed. It is therefore impossible to achieve accurate drug dosing and the potential for feed wastage and nutritional compromise is high. Therefore, as a fundamental rule, medications should be regarded as generally incompatible with enteral feed formulations.
If it is absolutely essential to give medications down the feeding tube, the tube must be flushed both before and after the drug delivery. Because each flush is 30-60ml, it should be noted that flush fluids can accumulate to substantial additional volumes over the course of a day.