Information Services frequently receive queries regarding the safety of crushing or otherwise manipulating medicines. These queries often originate with a prescriber who is reluctant to prescribe a liquid formulation either due to cost or the lack of a licensed liquid preparation.
Crushing tablets or opening capsules poses specific considerations for the pharmacist including:
- Bioavailability issues
- Practical issues, including patient adherence
- Legal or ethical implications
In many situations crushing tablets is unlikely to have any effect on the action of the medicine, however certain formulations should never be manipulated including modified release, enteric coated, hormonal, steroidal or cytotoxic medicines and medicines with a narrow therapeutic index.
- Modified release preparations- these products generally contain a larger dose of the drug than the immediate release product in a formulation that releases the drug slowly over a longer period of time. Crushing these tablets will destroy the slow release mechanism allowing the full dose to be released as a single dose, termed “dose dumping”. This increased dose could potentially lead to adverse reactions. An additional consequence of the release of a larger dose is quicker drug absorption and metabolism and a longer interval between doses where the drug level can fall to sub-therapeutic levels. Patients stabilised on modified release products that have difficulty swallowing should be converted to an immediate release form that can be crushed. This generally involves administration of a lower dose at more frequent intervals.
- Enteric coated products- Enteric coating prevents the release of the drug in the stomach. This either protects the drug from the acidic conditions within the stomach or protects the stomach from the effects of the drug. Crushing an enteric coated tablet would destroy the coating and potentially result in stomach irritation and/or reduced efficacy.
- Hormonal, steroidal or cytotoxic products- An important consideration with crushing these products is not only the safety of the patient but also the safety of the person crushing and administering the medicine. Hormonal medicines such as finasteride or tamoxifen, cytotoxic medicines such as methotrexate or steroidal products such as hydrocortisone or dexamethasone should not be crushed as this could result in powdered drug either coming into direct contact with the person’s skin causing sensitisation or being aerolised and inhaled. Allergies can also occur when medicines are crushed, this is particularly important with antibiotics where the powder comes into direct skin contact or is inhaled. Where crushing of these medicines is considered essential suitable measures must be put in place to protect the person crushing and administering the medicine.
- Medicines with a narrow therapeutic index- manipulating medicines can affect the drugs bioavailability. A small change in the bioavailability of a medicine with a narrow therapeutic index can result in safe and effective use becoming problematic and dangerous. Consequently it would be considered good practice never to recommend the manipulation of medicines with a narrow therapeutic index such as lithium, phenytoin, carbamazepine, digoxin, theophylline, warfarin or sodium valproate.
- Film coated tablets- film coating can may the tablet difficult to crush. Crushing can also result in particles of the coating remaining adversely affecting patient acceptability and adherence. Film coating is used for several reasons, most commonly making tablets easier to swallow, disguising unpleasant taste, preventing contact with medicines that can cause sensitisation or protecting the medicine from moisture. Crushing would obviously prevent the film coating from fulfilling these aims.
When advising on the suitability of medicines for crushing there are a number of issues that may affect patient safety. Key considerations would include:
- Stability issues- will the medicine react with air or moisture?
- Bioavailability- will the drug level be affected by crushing? Could this result in a risk of toxicity?
- Adherence- will crushing the tablet affect adherence? Crushed tablets can be unpalatable which can adversely affect patient adherence.
- Practical issues that could affect the full dose being taken, for example:
- Will the full crushed tablet be mixed or will there be any residue?
- Will tablet particles be lost during crushing?
- Will the crushed tablet dissolve fully or will sediment remain?
- Will all the liquid be taken?
- When will the tablet be crushed? Immediately before dosing?
- Who will crush the medication, the patient or carer? Are they aware of the issues?
- Will multiple tablets be crushed, potentially resulting in cross contamination?
Legal and ethical implications
Modification of a medicine, such as crushing a tablet or opening a capsule, will nearly always render use of the medicine outside of the terms of the product licence.
Pharmacists who advise patients to crush tablets or open capsules are effectively sanctioning the unlicensed use of a medicine and would be liable for any harm caused.
Where medicines are prescribed outside of their licence liability is shared between the prescriber, pharmacist and the person administering the medicine.
When pharmacists provide advice on the suitability or appropriateness of manipulating medicines they should always consider the patient’s clinical need, the option with the lowest patient risk and the urgency that the medicine is needed. It is strongly recommended that pharmacists maintain records of these decisions including the reason for altering the medicine, alternative options considered, discussions with the patient, carer or other healthcare professionals and also obtaining consent.