Extemporaneous preparation

A working definition of extemporaneous dispensing or compounding is the mixing together of the ingredients of a prescription or drug formula and generally refers to a manual process performed for individual orders by a dispenser or pharmacist86.

Extemporaneous preparation remains one of the highest risk preparative activities carried out in the pharmacy. This is largely due to the previously discussed dangers of using unlicensed medicines being amplified by the inherent risks associated with the pharmaceutical compounding process87 88. This is evidenced by several reported errors connected to the use of extemporaneously prepared medicines, resulting in serious harm to patients. The most notable incident in recent UK history was the ‘peppermint water case’ in which the use of the wrong strength of chloroform water led to the death of a child89.

It has also been argued that this risk may be exacerbated by a declining expertise in pharmaceutics and formulation within the pharmacy profession90 91 92. Compounding of oral medicines is often delegated to junior or trainee staff, and there is commonly no quality assurance system in place to support practice91. Until the publication of the Guide to the Preparation of Non-Sterile Extemporaneous Products in National Health Service (NHS) Hospitals93 in 2003, there were no agreed, detailed standards for this area of extemporaneous preparation in the UK.

In addition, there appears to be a relationship between the environment in which medicines are prepared, the level of quality assurance applied to the processes involved and ultimately, the level of residual risk to patients. As one might expect, preparation in clinical areas and extemporaneous preparation in the pharmacy is considered to represent the lowest levels of quality assurance and the highest risk, whereas manufacture of licensed medicines provides the most robust assurance of quality, safety and efficacy. Manufacture of unlicensed medicines under a manufacturer’s ‘Specials’ Licence (MS) represents a level of intermediate overall quality and risk.

A key objective for clinical governance of unlicensed medicines is to ensure that use of products prepared in clinical areas or by extemporaneous preparation in the pharmacy is limited in favour of products manufactured under a manufacturer’s ‘Specials’ license (MS) or, ideally a full manufacturer’s license.

Progression of Risk 88


As unlicensed medicines, very few extemporaneous preparations are supported by any data to demonstrate a suitable absorption profile and/or bioequivalence with a licensed preparation. Even where a given formulation has been shown to achieve suitable physical, chemical and microbiological stability, the bioavailability and palatability of the preparation may be unproven. However, it is recognised that some patients may have special clinical needs that cannot be met by licensed medicinal products or by a viable alternative option. In these circumstances it would be inappropriate to curtail the patient’s treatment. Whenever carrying out an individual risk assessment, the risks of not treating the patient should also be considered and be at the forefront of the decision-making process.