Manipulating solid dosage forms
Prescribers may advise patients that manipulating solid dosage forms is a suitable alternative to a liquid special, and advise them to seek the advice of the pharmacist. This form of administration will be outside of the product's marketing authorisation (licence) and as such pharmacists will share liability with the prescriber for any patient harm.
When advising on the crushing or dissolving of tablets or the opening of capsules there are a number of issues that can affect patient safety.
Consideration should be given to the following factors:
- Stability issues - does the medicine react with air/water? Note that confirmed stability does not imply clinical safety.
- Bioavailability issues - will blood levels be affected by crushing? Is there a risk of toxicity due to immediate release?
- Adherence issues – will crushing tablets affect adherence? Crushed tablets are sometimes unpalatable which will result in the patient being less likely to take their medication.
- Practical issues regarding the full dose being taken, for example:
- Will the full crushed tablet be mixed, i.e. any residue?
- Will tablet particles be lost through crushing?
- Will it dissolve fully? Will sediment/particles remain at the bottom of the vessel?
- Will all the liquid be taken?
- When will the tablet be crushed? Immediately prior to dosing?
- Who will crush all the medication? Patient or carer? Are they aware of the issues?
- Will there be cross contamination when crushing multiple tablets?
Many tablets now have a film coating which may make the tablet difficult to crush and particles of film coating may remain. Film coating is used for a variety of reasons, including:
- Making medicines easier to swallow.
- Masking unpleasant tastes such as for ibuprofen or quinine.
- Preventing contact sensitisation when handling medicines such as chlorpromazine.
- Protecting the medicine from moisture.
While in many cases crushing tablets is unlikely to cause any harm to patients there are certain formulations that should never be manipulated including modified release preparations, enteric coated tablets, hormonal or cytotoxic medicines and medicines with a narrow therapeutic index.