Alternative formulations
Traditionally liquids or dispersible tablets would be the first choice for patients who retain a limited ability to swallow. Where these products are used it is important to ensure that the product is a consistency that the patient is able to swallow safely.
When advising on the suitability of liquid products pharmacists and prescribers should remember that sorbitol containing products can cause diarrhoea when given in large volumes whilst hyperosmolar liquids, such as lactulose, can cause nausea, bloating and diarrhoea. Dilution of hyperosmolar liquids will reduce their osmolarity and consequently reduce the incidence of adverse effects.
Liquid products have key advantages over other formulations including:
- Potency is designed to provide a standard dose in a 5ml dosage.
- Taste of the drug is masked by added flavours or other ingredients.
- Suspending agents ensure an even distribution of the drug in each dose.
- Solvents are chosen to maximise drug stability.
Dispersible or effervescent tablets - Patients with moderate swallowing difficulties can normally manage to take dispersible or effervescent tablets. These tablets should not be mixed with liquids other than water, unless indicated in the product information, as this would result in the administration being outside of the product licence. Dispersible tablets do not disperse evenly within the liquid which may impact on dose accuracy where only a partial dose is prescribed or administered.
Unlicensed liquid specials - Where a licensed liquid or dispersible tablet is not available prescribers may consider an unlicensed liquid special.
Liquid specials are often expensive which has resulted in prescribers being reluctant to use them. These products are unlicensed and the quality of the product, patient acceptability, shelf life and cost can vary. Where patients are prescribed a liquid special it is recommended to source the product from the same supplier each time to ensure product consistency, and wherever possible order batch specials with a certificate of analysis rather than individually produced bespoke specials with a certificate of conformity. The extent of quality assurance testing will be greater for batch specials than bespoke products.
Pharmacists accept a higher level of product liability when dispensing unlicensed specials than when supplying licensed medicines. This is because where a patient is harmed by a licensed medicine the liability rests with the manufacturer, while for an unlicensed special this liability rests with the pharmacist and prescriber.
For a full discussion on the use and supply of specials and unlicensed medicines refer to Pharmacy Excellence, Unlicensed Medicines and Specials.