Key messages

  • As we age, physiological changes can affect the way our body metabolises drugs, causing adverse reactions.
  • Older people are more likely to be taking multiple medications (‘polypharmacy’), which increases the risk of medications being implicated in hospital admissions.
  • Up to 30 per cent of hospital admissions of people aged 65 years and over are medication-related, and approximately half of these could be prevented1.
  • Medication-related admissions in older people can be caused by adverse drug reactions, failure to take a prescribed medication and errors with taking medications.

“Medicines…have the potential to provide great gains as well as significant harms to older people” [2]

Physiological changes can cause adverse reactions

Medicines can be problematic for older people because as we age physiological changes can affect the way our body absorbs, distributes, metabolises and eliminates drugs. These physiological changes include increased body fat, decreased body water, decreased muscle mass, and changes in renal and liver function and in the Central Nervous System. These changes can cause adverse drug reactions (ADRs) in older people.

Frail older people are more likely to have pronounced changes in response to medicines. Generally, medications in frail older people aim to control symptoms and help maintain function.

For older people there can also be a higher risk of unintended consequences of medical treatment (iatrogenesis) related to medication.

Polypharmacy increases risk of adverse events and errors

As people age they are more likely to be taking several medications, including prescribed medications, over the counter or complementary medicines.

Taking multiple medications – known as ‘polypharmacy’ – increases the risk of medications being implicated in hospital admissions, particularly when an older person presents with falls, confusion or incontinence3. Polypharmacy can cause problems due to prescribing errors, problems with taking the medicines, and interactions of medicines.

When people take multiple medications, they are at greater risk of:

  • falls and associated harms, such as fractures
  • dehydration
  • functional decline
  • cognitive impairment
  • delirium
  • declining nutritional status
  • adverse drug reactions
  • hospitalisation
  • mortality4.

Also, the more medications a person takes, the greater the risk of medication errors. These errors may be due to difficulty in getting an accurate medication history and review, in prescribing and in following complex medication regimes.

An average of five to seven medication changes are made during the hospitalisation of an older person5, which also increases the risk of prescribing errors and adverse drug events.

Hospital admissions can be related to medications

It is estimated that up to 30 per cent of all hospital admissions of people aged 65 years and over are medication-related, and approximately half of these could be prevented6.

Medication-related admissions in older people can be caused by:

  • ADRs
  • failure to receive or take a prescribed medication
  • errors with taking medications.

1. Roughead, E. E., Semple, S. J. Medication safety in acute care in Australia: Where are we now? Part 1: a review of the extent and causes of medication problems 2002–2008. Australia and New Zealand Health Policy 2009. 6: p. 18.

2. Hilmer, S. N., Gnjidic, D., Le Couteur, D. G. Thinking through the medication list: appropriate prescribing and deprescribing in robust and frail older patients. Australian Family Physician 2012. 41: pp. 924-28.

3. Elliott, R. A. Problems with medication use in the elderly: an Australian perspective. Journal of Pharamacy Practice and Research 2006. 36: pp. 58-66.

4. Hilmer, S. N., Gnjidic, D. The effects of polypharmacy in older adults. Clinical Pharmacology and Therapeutics 2009. 85: p. 86.

5. Elliott, R. A. Problems with medication use in the elderly: an Australian perspective. Journal of Pharamacy Practice and Research 2006. 36: pp. 58-66.

6. Roughead, E. E., Semple, S. J. Medication safety in acute care in Australia: Where are we now? Part 1: a review of the extent and causes of medication problems 2002–2008. Australia and New Zealand Health Policy 2009. 6: p. 18.