Unit 5 – Prescribing in Practice

Storage, Handling and Disposal of Drugs, including Calculation


It is important to ensure that any medicinal products kept at the practice are stored under correct conditions. Certain products require refrigeration between 2°C and 8°C, and some products must be protected from contamination, atmospheric moisture, sunlight and adverse temperatures.

For example, flu vaccines should be stored in the fridge and removed half an hour before they are needed. If they are left too long at room temperature there is a strong possibility that they will fail to have the desired therapeutic effect. Therefore it is imperative to follow correct storage requirements.

Refer Back

Link to 'Policies regarding the use of microbials' in Unit 3. Prescribing and the Wider Healthcare Context.

Where possible, it is also wise to store medicinal products in their original packaging, as this enables easy identification of the batch numbers and expiry dates. This is particularly useful if there is a manufacturer's recall of a product, and also makes it easier to check for out-of-date stock.

Schedule 1,2 and 3 Controlled Drugs (CD) — with some exceptions — require safe custody. Consequently, if they are stored at practice premises, they must be kept in a locked safe, cabinet or room, which is designed to prevent unlawful access.

This means that if they are kept at the practice premises they must be kept in a locked safe, cabinet or room, which is designed so that no one may unlawfully access it.


Think about how you store your medicinal products. Are they stored at the correct temperature and under the right conditions? If not, rectify the situation!

In the UK, the International System of measurement (SI) is almost always used.


You should be aware of any precautions deemed necessary when handling the medication and medicinal products that are kept at your practice.


Have a look at the medicinal products you store. Do any of them require specific handling?


It is a good idea to encourage patients to return their unwanted medicines to the pharmacy, as these can then be stored in special containers and appropriate methods taken to dispose of them.

You need to make yourself aware of any local policies on the disposal of medication in your clinical area.

Measurements and calculations



Eggleton, A. G. (2004) Calculation skills in Courtenay, M. and Griffiths, M. Independent and Supplementary Prescribing: An Essential Guide. London: Greenwich Medical Media. Chapter 12.

There are some useful self-tests for practice calculations within this chapter.

Most nurses consider themselves to be practical, helpful people, maybe even doers rather than economists or mathematicians, yet in their day-to-day lives they practice forms of measurement all the time.

There are many sources of drug dosage information. These are developed to ensure drug uniformity and are recognised as reliable. You have been issued with a Nurse Prescribers' Formulary, which is jointly published by the British Medical Association and the Royal Pharmaceutical Society of Great Britain. The NPF is an excellent source of detailed information on the possible side-effects, cautions, contraindications and dosages of medicines.


Think of other sources of prescribing information. What type of information might they provide and how accessible is this?

In the UK, the International System of measurement (SI) is almost always used. The common language of this system allows standard measurement to be understood worldwide.



If you need revision on this topic:

Haigh, S. (2002) How to calculate drug dosage accurately: advice for nurses. Professional Nurse 18: 1, 54-57.

Calculation of dosages

Miscalculation of drug dosages can result in patient morbidity or mortality, ruin your career and damage the reputation of your employing body.

The normal prescribed dose must take into account factors such as the patient's age, weight and general health.

The aim is to give a dose that is sufficient to exert the desired effect while avoiding adverse effects, but that is not so low as to be ineffective.

The dose recommended for drugs is to allow a level to be established in the blood, which is within the therapeutic range.

Rules for doses

  • The prescription should include the quantity required, while considering the pack size
  • Never write milligrams if the medication is supplied in grams
  • Although the word milligrams is plural, the abbreviation is mg, not mgs. Similarly, other decimal abbreviations do not take an 's', so the word millilitres is abbreviated to ml
  • For safety, write nanograms in full: handwritten ng and mg can look similar, 1mg = 1,000,000 nanograms, making massive overdoses possible
  • At the end of any calculation, always ask yourself: 'Does that sound reasonable?'

The prescription should state the following quantities:

  • If less than 1 microgram, state in nanograms
  • If less than 1mg, state in micrograms
  • If less than 1g, state in milligrams
  • For liquids, state the strength per ml

Note: It is acceptable to use the abbreviations ml, mg and g, but nanograms and micrograms should never be abbreviated.

Further Reading

Further reading

Gatford, J., Anderson, R. (2002) Nursing Calculations (6th edition). Edinburgh: Churchill Livingstone.

Lapham, R., Agar, H. (1995) Drug Calculations for Nurses: A step-by-step approach (2nd edition). London: Arnold.

Volans, G., Wiseman, H. (2003) Drugs Handbook 2003. London: Palgrave Macmillan.

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