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A flow chart to reduce insulin repeat prescription errors

Val Brown, Shelpa Parmar

Repeat insulin prescriptions issued both in hospital and in the ­community are often inadvertently inaccurate, and may result in the wrong type of insulin being ­dispensed. This article describes the development of a flow chart designed to assist staff who prepare prescriptions in reducing such errors. The chart, originally produced two years ago, has now been updated and is reproduced here as a pull-out centre-page section.

There are now available numerous insulins, insulin mixtures, insulin pens with cartridges of different sizes, and disposable pens made by different manufacturers — all of which may lead to confusion when repeat prescriptions for insulin are issued. Common difficulties in prescribing include errors regarding the numerous insulin mixtures, incorrect source of insulin (i.e. insulin analogues, ‘human’ insulin, pork insulin or beef insulin) and incorrect cartridge size or type appropriate for the pen. 

To address this problem, the diabetes specialist nurse (DSN) at Community Health South London NHS Trust collaborated with the community trust pharmacist to prepare a flow chart that illustrates the full range of available insulins, together with the format in which they are dispensed. The aim of the chart is to improve the accuracy of repeat prescribing for insulin.

How the work was initiated
Three years ago, Community Health South London contracted with Lambeth, Southwark and Lewisham Health Authority to provide a package of support to a GP practice serving a population of 5000 patients. This was part of the Government-led personal medical services (PMS) pilots, which aim:

  • To offer a more flexible environment for the recruitment and retention of staff working in general practice.
  • To explore different organisational arrangements for the delivery of high quality primary care services.

The PMS pilots allow the health authority to contract with community trusts, GP practices, other trusts and other organisations, which then become accountable for the delivery of the contract. Under these arrangements, PMS pilots are able to test  the effectiveness of different organisational models in managing general practice. 

The community trust model includes  salaried GPs, nursing staff, administrative personnel and a pharmacist. The presence of a pharmacist in the GP practice has facilitated liaison with the local DSN to resolve the problem of repeat prescribing for insulin.

Identifying the problem
Normally clerical and nursing staff in a GP surgery prepare repeat prescriptions on the computer system for the medical staff to sign. Insulin manufacturers may have little contact with the members of the general practice team involved with the repeat prescribing process. These staff may rarely have the opportunity to familiarise themselves with the appearance of the different insulin presentations and pack sizes available.

The current pharmaceutical literature emphasises stock ordering requirements including wholesaler order numbers (Pharmaceutical Interface Product (PIP) codes) but these may not assist general practice staff. A comprehensive and easily understood guide to all insulin products is not currently available. A flow chart was therefore constructed in response to this deficiency to meet GP practice needs. 

The aims of the chart were:

  • To provide a list of all available insulins
  • To provide a list of all available insulin presentations, i.e. vials, cartridges and disposable pens
  • To identify different cartridge sizes
  • To identify items not available on prescription.

The chart was presented as an A3 poster (see PDF of this article).

Prescription examples
Figure 1 shows a hand-written prescription for Human Actrapid and Human Insulatard to illustrate the confusion that can occur as the result of the different presentations of pens, cartridges, quantity and pack size. 

The cost of the prescription as written is:

  • 15 packs Actrapid penfill cartridges (1.5ml) = £148.05 (total 75 cartridges)
  • 15 packs Insulatard penfill cartridges (1.5ml) = £148.05 (total 75 cartridges)
  • Total cost of 150 cartridges = £296.10.

This prescription is actually intended to provide 15 cartridges of each insulin type (30 cartridges) at a total cost of £59.22.

Figure 2 shows a computerised prescription, illustrating a typical error; the cost of this prescription would have been:

  • 100 x 3ml Human Mixtard 30 pens = £526.60.

It is more usual to give 2–4 packs. Once the insulin has been dispensed at the pharmacy and taken home it cannot be returned to the pharmacist for re-use.

This chart was designed jointly by a DSN and a pharmacist and was piloted within a GP practice participating in a PMS pilot. It has been widely welcomed both by the staff in this setting and by a wider audience. It appears to have met a long-awaited need. This initiative illustrates one of the benefits of having a GP practice-based pharmacist to help contain some of the costs of repeat prescribing in primary care (Wells, 1998).

The insulin flow chart needs to be kept constantly up to date and requires ongoing funding. Diabetes & Primary Care journal is pleased to help produce this updated version to meet the continued demand for the chart.

Use of the flow chart clarifies the repeat prescription procedure for insulin and prevents wastage of resources. Its production demonstrates the effectiveness of collaboration between health professionals within the PMS model to improve patient care.


Wells WD (1998) Having a practice pharmacist can reduce prescribing costs. British Medical Journal 317: 473

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