How to prescribe for administration via enteral feed tube

The administration of drugs via an enteral feeding tube requires extensive consideration and there a numerous factors both legal and professional which need to be addressed.

The main concern is tube blockage. If this occurs, the patient may have to be re-admitted to hospital to have their tube re-sited. This is not only unpleasant and inconvenient to the patient, it is also a significant cost to the primary care trust.

• Before deciding to administer a drug via an enteral feeding tube, a practitioner must first consider whether continuation of the medicine is imperative, or whether stopping the medicine either temporarily or in the long term would be more appropriate
• If deemed imperative to continue the medicine, alternative formulations such as patches or suppositories should be considered. Using the enteral feeding tube to administer medicines should be a last resort
• If the oral route is the only viable route, and this is only available via a feeding tube, a liquid formulation, including soluble or dispersible tablets should be used.
• The consistency of the liquid medicine should be carefully considered as they can block tubes
• If a drug is not available as a liquid, consideration should be given to another drug within the same therapeutic class which may be available as a liquid
• Dose calculations may be required as the bioavailability may vary between solid and liquid preparations. This is important for drugs with a small therapeutic index or modified release preparations. Occasionally, the salt of the drug is different in the liquid when compared to the solid form and again this can cause differences in the amount of actual drug prescribed e.g. phenytoin.
• Caution is advised when prescribing large quantities of some liquid preparations containing the sweetener and sugar substitute, sorbitol due to its laxative effect when given in high doses.
• Crushing of tablets or opening of capsules should only be considered as a last resort and when a pharmacist has confirmed the medicine is safe to be crushed or opened. Medicines that should never be crushed or opened include:
  • Modified release preparations
  • Enteric coated preparations
  • Buccal or sublingual tablets
  • Cytotoxics and hormonal products
• Once daily dosing regimens are preferable for enteral administration as this reduces the number of feed manipulations needed
• Some drugs will not be suitable for administration via an enteral tube. Antacids are an example of such medications, which would be rendered ineffective if administered down a feeding tube with the distal end in the intestines because it would be unable to neutralise stomach acid as intended.

The prescription itself needs to clearly state the formulation to be supplied but adequate communication around the prescription is essential to ensure administering practitioners are aware of the intended route and method of administration. If a tablet is to be crushed or capsule opened, in order to administer it down a feeding tube, this practice will render the formulation unlicensed. As such, liability for any harm that ensues will lie with the administering practitioner. Practitioners should therefore document that they wish the tablet to be crushed or capsule opened, so that liability can be shared.

An appropriate tablet crushing or capsule opening technique is essential to ensure the patient receives the full dose, safely and without compromising the feeding tube. Guidelines as to how to administer medicines via a feeding tube are available, including those for best practice in crushing tablets and opening capsules. These should be followed and where possible, local procedures should be implemented, ensuring that all practitioners involved in the prescribing and administration of drugs via enteral feeding tubes are knowledgeable and fully aware of all the associated issues.

It is important to remind patients that the tube should always be flushed before and after administering medicines and with a small amount of water between different medicines. This is to reduce the chances of blockage.

Flushing should always be undertaken with a 50mL syringe.

A further consideration when prescribing for administration via enteral feeding tubes is the potential for interactions between the feed and the medicine. If in doubt, a pharmacist will be able to advise you.

For detailed evidence-based guidance on giving medicines via enteral feed tubes we recommend:

Handbook of Drug Administration via Enteral Feed Tubes. R.White & V.Bradman – published by The Pharmaceutical Press.