Intended for healthcare professionals

Student Education

Prescribing for older people

BMJ 2007; 335 doi: (Published 01 October 2007) Cite this as: BMJ 2007;335:0710372
  1. Louise E Cotter, medical student1,
  2. Una Martin, senior lecturer in clinical pharmacology1
  1. 1University of Birmingham

What do you need to be aware of when prescribing for elderly people? Louise E Cotter and Una Martin discuss


Prescribing is an essential skill in clinical practice, which requires a sound knowledge of the principles of therapeutics. Many factors influence the way the body handles drugs and the effects seen. Age is particularly important.

If you have ever been attached to a medical firm when it is on call for acute admissions you will know how important it is to prescribe drugs safely to elderly people. About 15% of the population in the United Kingdom is older than 65, and the number of elderly people will continue to rise in the 21st century. The prevalences of many diseases are related to age, and several diseases may coexist in the same patient—for example hypertension, osteoarthritis, and prostatic hypertrophy. Prescribing for these and other conditions means that elderly patients consume half of all prescribed items, and their drug regimens are often complex. The use of cardiovascular drugs, diuretics, analgesics, and hypnotics are particularly common in this age group. In addition, elderly people tend to be high consumers of over the counter preparations, including vitamins, analgesics, and herbal remedies, which may interact with prescription drugs. Finally, both long duration and polypharmacy characterise drug treatment in elderly people. For all these reasons elderly patients may be particularly vulnerable to adverse drug reactions.

Adverse drug reactions

Adverse drug reactions are often a consequence of multiple drug prescribing, which leads to drug-drug interactions. There are many mechanisms involved, including inhibition or induction of drug metabolism by the cytochrome P-450 system in the liver. For example, inhibition of cytochrome P-450 isoenzymes by ciprofloxacin may reduce the metabolism of warfarin, leading to a dangerous increase in the prothrombin time.

Another important drug-drug interaction occurs when a pharmacological interaction between …

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