Antibiotics are consistently and widely used in almost all areas of clinical healthcare in Australia with 38% of hospital patients being treated with a microbial on any given day (2014) and 46% of the general population being dispensed at least one systemic antimicrobial prescription in the community (2014-2015).
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Increased medicine use in Australia combined with an ageing population has lead to rising cases of polypharmacy with approximately 66% of Australians aged 75 years and above taking five or more medicines and more than 20% using 10 or more (2009-2012). Increasing rates of antibiotic use and polypharmacy undoubtedly overlap and it is important to recognise the potential for antibiotic interactions (or any interaction for that matter) when deciding on any course of pharmacotherapy.
The range of different antibiotics with differing pharmacological characteristics lends to a complexity that can often be overlooked. For example, many interactions take place at the absorption stage, meaning medications such as antacids and antimotility preparations can delay and reduce the absorptions of antibiotics such as tetracyclines and clindamycin by combining with them in the GI tract to form chelates or complexes.
Another result of antibiotic interactions is the potentiation of toxic side effects. Most antibiotics implicated in this type of interaction are those that possess some form of toxicity such as aminoglycosides, cephalosporins, and tetracyclines.
While there are several clinically useful drug-drug interaction checkers (e.g. Stockley’s Drug Interactions, MIMS Drugchecker, AusDI, Lexi-Interact, Micromedex and the AMH), many of these are subscription only tools. Furthermore, while a checker tool may produce an interaction result, it is ALWAYS essential to consider its contextual clinical significance.
If you have any questions regarding pharmacology and medications, including interactions, contact the Hunter Drug Information Service (HDIS) on (02) 4014 3695.
- Australian Commission on Safety and Quality in Health Care. AURA 2016 – First Australian report on antimicrobial use and resistance in human health. (June 16, 2016).
- Australian Medicines Handbook. Adelaide: Australian Medicines Handbook Pty Ltd; 2016.
- MIMS annual 2016. St Leonards, Australia: UBM Medica Australia.