Enteral administration
1. Oral administration
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 administration might be a suitable option.
For patients with swallowing difficultites think about alternative routes or drugs. Sometimes a liquid formulation may be appropriate but not all patients can safely swallow thin liquids. You may need to consider crushing tablets or opening capsules and mixing them with soft food or thickened fluids.
For patients with swallowing difficultites think about alternative routes or drugs. Sometimes a liquid formulation may be appropriate but not all patients can safely swallow thin liquids. You may need to consider crushing tablets or opening capsules and mixing them with soft food or thickened fluids.
Note that certain tablets must not be crushed as they can pose risks. 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). Remember that crushing a tablet, dissolving it in water, or opening a capsule may be an unlicensed use.
Patients with part of their gut removed may still be able to take medicines orally. Establish which section of gut has been removed and check the site of drug absorption.
Often information on manipulating formulations such as crushing tablets and mixing with food is relatively lacking. This is also the case for trying to find out exactly where in the gut medicines are absorbed. Consider if you can monitor for effectiveness (e.g. measuring blood pressure with an antihypertensive).
Common clinical problems
- Advising on the care of NBM patients (e.g. patients undergoing surgery).
- Finding appropriate medicines and/or formulations for patients with swallowing difficulties (e.g. patients with stomatitis).
2. Administration through enteral feeding tubes
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 range 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.
- 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).
- Some tubes inserted into the stomach through the abdominal wall have an extension tube that ends in the jejunum. These are called PEG-J tubes.
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| An illustration of a nasogastric tube in place |
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.
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 hospital pharmacist 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.