Deciding to use an injectable

Before deciding to use an injection enterally (orally or via a feeding tube) follow our guide to choosing formulations in people with swallowing difficulties.

The decision to use an injection enterally should be made on an individual patient basis after consideration of the clinical risks and benefits.

Once a decision is made to give an injection enterally, clearly document in the Patient’s Medicines Administration record (MAR) chart, notes and care plan.

Product suitability

Consider the following when deciding which injectable product to use.

Off-label use

Most injections are not licensed for enteral administration. Use in this way will be considered off-label.

Prescribers assume greater liability when using licensed injections off-label. The injection may not have the same safety and effectiveness assurances as when used according to its Summary of Product Characteristics (SmPC).

Bioavailability

The material used in feeding tubes can affect the bioavailability of some medicines. For example, the bioavailability of diazepam may be reduced by adsorption onto PVC tubing.

Injectable medicines that are sensitive to stomach acid may not be appropriate for enteral administration. Injectable formulations do not have gastroprotection from the low pH of stomach acid, whereas tablets and capsules may be formulated with coatings to protect the drug.

Taste

When administered orally, the taste of an injection can be unpleasant for the patient. For example, acetylcysteine injection has a bitter taste which can be overcome by diluting with fruit juices or cola.

Taste is not an issue when the injection is given through an enteral feeding tube.

Side effects

Medicines, such as mexiletine, can have an anaesthetic effect on the tongue. In these cases, patients should be advised to be careful when eating and drinking, particularly with hot food and drink.

Cost

The use of injections enterally is a relatively expensive method of administration compared to oral dosage formulations.

Preparation

Consider the following when preparing injectable medicines for enteral use.

Health and safety

When preparing injectable medicines for enteral administration there may be a risk of side effects from inhalation or topical exposure. This may be of particular concern for certain classes of medicines such as cytotoxics, antibiotics and hormones.

To overcome this, ensure appropriate Personal Protective Equipment (PPE) is used when preparing medicines.

Complex manipulations

Preparation of an injection for use enterally may require additional manipulations or processes in comparison to standard enteral formulations. These additional manipulations may include:

• Reconstituting vial contents.
• Drawing the contents of a vial or ampoule into an enteral syringe.
• Using the displacement value to calculate volume.
• Using a partial vial or ampoule, or using more than one to prepare the dose.
• Handling of sharps.

Unfamiliarity with these processes may introduce a risk of error. If patients or carers are unable to safely undertake the manipulations required, a more practical option should be offered.

Equipment

Consideration should be given to the supply and availability of necessary equipment. For example, appropriate syringes and needles cannot be prescribed on an FP10 prescription.

Equipment supplies may include:

• Oral or enteral syringes for the administration of all medicines via the enteral route.
• Filter straws to reduce the risk of ingestion of glass shards from broken ampoules.
• Blunt filter needles to reduce the risk of particles when reconstituting or withdrawing from a rubber bunged vial.

Waste handling

Provide patients with sharps bins and advise on appropriate arrangements for disposal. Arrange for additional provisions to manage waste and spillages when using cytotoxic medicines.

Monitoring

Since the usual assurances about safety and efficacy cannot be given when using a licensed injectable off-label, monitor the patient:

• For any signs of an increase in side effects.
• For any signs of failed therapy.
• Serum drug levels more closely for recommended medicines.

Use across care boundaries

Using an injection enterally may add complexities related to safe use across care boundaries. Consider implementing risk mitigation strategies to minimise potential harm.

Recommended resources

The following resources may be helpful:

• Some SmPCs may state that the injection can be given orally or via an enteral feeding tube. If so, the use of the injection in this manner is licensed.
• The NEWT guidelines (subscription required) provides information on medicines administration for people with swallowing difficulties or feeding tubes. It includes information on the administration of some injectables enterally.
• The Handbook of drug administration via enteral feeding tubes (subscription required) provides information on medicines administration via feeding tubes. It includes information on the administration of some injectables enterally.

Further information

If relevant information is not available on the SPS website or the information resources listed, or if your clinical scenario is complex, we suggest you seek further advice.

Primary care healthcare professionals can get in touch with the SPS Medicines Advice service.

Secondary care healthcare professionals can contact the local medicines information service or clinical pharmacist for further support.