Enteral administration

Last updated: Tuesday, July 12, 2022

1. Oral administration

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You will often be asked for help in managing oral administration problems. Think laterally and be inventive. For example, if a patient is going to be nil-by-mouth (NBM) prior to surgery but normally takes levothyroxine, it may not matter if they miss one or two doses, as the half-life is about 7 days. Similarly, if the patient takes simvastatin for hypercholesterolaemia missing several doses won’t matter, since atherosclerosis is a chronic process.

However, if the same patient takes carbamazepine for epilepsy, they cannot miss any doses and you need to think about alternative routes, in this case rectal might be a suitable option.

For patients with dysphagia where no licensed liquid formulation exists think about alternative routes or drugs, using injections orally, specials manufacturers, crushing tablets or opening capsules. Some conventional tablets are soluble in water (e.g. ciprofloxacin), but note that certain tablets must not be crushed as they can pose dangers. These include: enteric-coated tablets (crushing destroys the protective coating), slow-release tablets (crushing stops the prolonged action), and chemotherapy drugs (crushing could release cytotoxic dust).

Patients with part of their gut removed may still be able to take medicines orally. Establish exactly which section of gut has been removed and check the site of drug absorption.
Common clinical problems
  • Advising on the care of NBM patients (e.g. patients undergoing surgery).
  • Finding appropriate medicines and/or formulations for patients with dysphagia (e.g. patients with stomatitis or after a stroke).

2. Administration through enteral feeding tubes

A nasogastric tube in an adult shown here in black
Courtesy of Nanoxyde, Wikimedia Commons

Enteral feeding is indicated in patients who cannot ingest food normally but whose gastrointestinal tract is able to digest and absorb sufficient nutrients (e.g. patients with head and neck cancer or following a stroke). A variety of methods are used to deliver enteral feeds:

  • Nasogastric (NG) tubes are inserted through the nose into the stomach. They are used for short-term feeding only.
  • Percutaneous endoscopic gastrostomy (PEG) tubes are inserted through the abdominal wall into the stomach via a stoma. They may be used for long-term feeding.
  • Jejunostomy tubes may be inserted through the nose (NJ) or through the abdominal wall (PEJ).

Enteral feeding tubes can be used to administer drugs but care must be taken to check that the tube does not bypass the site of absorption (e.g. iron is mainly absorbed in the duodenum and jejunal administration will therefore reduce bioavailability). In addition, drugs can interact with the feed (e.g. phenytoin) or cause the tube to block (e.g. insufficiently crushed tablets). NG tubes are long, fine bore tubes which block easily. PEG and PEJ tubes are shorter with a wider bore.

Enteral feed may be administered as a bolus, intermittent or continuous infusion. Try to administer drugs in the gaps when the tube is not being used for feed, remembering to flush with sterile water before and after each drug. If a liquid formulation of a medicine is unavailable or unsuitable then consider using injections orally, changing the drug or route of administration, opening capsules or crushing tablets. However, enteric-coated tablets, modified-release tablets, or cytotoxic drugs must not be crushed, as above. 

Administration of most medicines through enteral feeding tubes is unlicensed practice.
 Common clinical problems
  • Advising how to administer drugs through enteral feeding tubes (e.g. crushing tablets, availability of liquids, giving injections orally).
  • Managing interactions between drugs and enteral feeds (e.g. sucralfate).
  • How to unblock enteral feeding tubes.

AUDIO: Medicines and PEG tubes
It's valuable to learn from other healthcare professionals how they manage their patients, and to hear their views on how the pharmacist can help. Listen to Helen Jones interviewing Sue Green, a Community Nutrition Nurse in Hampshire. Sue talks about the practical problems faced by patients with a PEG tube and those who care for them, and the part a pharmacist can play in optimising their medicines. Click on the 'play' arrow below.

If the audio does not work then this help page may assist you.

3. Buccal/ sublingual administration

These routes of administration will not generate many clinical problems but they may occasionally be useful to consider in some situations where you’ve exhausted other potential routes or where alternatives are less convenient (e.g. sublingual buprenorphine for heroin withdrawal).