Indications for fixed-dose combination medicines
Choose fixed-dose combination medicines (FDCs) according to clinical need
Therapy should not be chosen based solely on the possibility of improved adherence, convenience or cost advantages of the FDC preparation. Prescribing data indicate an increasing use of fixed-dose combination medicines even when guidelines and PBS-listing restrictions require a single agent as first line.
Reserve fixed-dose combination antihypertensives for use when initial management with a single antihypertensive is ineffective.1 However, a study in an Australian military veteran population assessed the use of four fixed-dose combination antihypertensive medicines and found only a small number of patients had been dispensed the corresponding individual medicines 12 months before starting the fixed-dose combination.2 Fewer than 1% of those in the study were taking each individual medicine before starting the fixed-dose combination, 29% were taking one of the individual medicines, 58% were taking antihypertensive medicines other than the individual ones in the fixed-dose combination, and 12% were receiving no antihypertensive therapy.2
Type 2 diabetes
Add-on therapy with either a sulfonylurea, basal insulin, a DPP-4 inhibitor or a GLP-1 agonist should be used when glycaemic targets have not been met using metformin monotherapy adjunct to healthy eating and exercise.3
A study of prescribing of glucose-lowering agents in an Australian military veteran population demonstrated a higher-than-expected prescribing of metformin–glitazone fixed-dose combination products despite guidelines at this time recommending metformin as first-line therapy followed by addition of a sulfonylurea if patients were not adequately controlled.4 This study found that:
- around 22% of veterans with diabetes were prescribed this fixed-dose combination medicine without any prior use of constituent agents or a sulfonylurea
- 57% of fixed-dose combination initiations occurred after a step-up from metformin alone; however, the PBS listing at the time only permitted use when metformin therapy alone failed and a sulfonylurea was contraindicated
- only 30% of initiations occurred after patients had been treated with metformin and rosiglitazone as separate medicines
- 10% of patients started on the fixed-dose combination medicine also received concurrent prescriptions for metformin, suggesting that either:
- dose escalations were required to achieve adequate control that could not be achieved using the fixed-dose combination, in which case the fixed-dose combination failed to fulfil it's primary purpose to reduce pill burden, or
- inadvertent duplication of fixed-dose combination and single-agent prescriptions was occurring.
Children with asthma
In 2011 a Drug Utilisation Sub-Committee (DUSC) review indicated a very high rate of children being started with a fixed-dose combination of inhaled corticosteroids (ICS) and inhaled long-acting beta-agonists (LABAs) without prior use of a single-ingredient ICS inhaler, as recommended by guidelines.5
This followed an earlier finding that 40% of children were supplied with a fixed-dose combination medicine without being prescribed an earlier single-ingredient ICS.5
Combination ICS–LABA inhalers should not be used as first-line preventers for persistent asthma in children because of the ongoing concerns about the side-effects.6
A postmarket review of starting asthma medicines in children is being undertaken.5 DUSC recognised this is a complex area of treatment and further clarification of the issues surrounding asthma management in children is needed.5
For more information
- Key messages on fixed-dose combination medicines
- Definition of fixed-dose combination medicines
- Place in therapy of fixed-dose combination medicines
- Prescribing tips for fixed-dose combination medicines
- Adverse effects of fixed-dose combination medicines
- Resources on fixed-dose combination medicines for your patients
- Therapeutic Guidelines. Cardiovascular. Version 6. Revised 2012. Melbourne: Therapeutic Guidelines Ltd. [Online] (accessed 28 February 2013).
- Gadzhanova S, Ilomaki J, Roughead EE. Antihypertensive use before and after initiation of fixed-dose combination products in Australia: a retrospective study. Int J Clin Pharm 2013;35:613–20. [PubMed]
- Gadzhanova S, Gillies M, Roughead E, et al. Fixed dose combination diabetes medicines – usage in the Australian veteran population. Aust Fam Physician 2011;40:811–5. [PubMed]
- Therapeutic Guidelines. Endocrinology. Version 5 (1), 2013 Melbourne: Therapeutic Guidelines Ltd [Online] (accessed 12 December 2013).
- Australian Government Department of Health. Post-Market Review of Pharmaceutical Benefits Scheme medicines used to treat asthma in children. 2013. [Online] (accessed 9 October 2013).
- Robinson PD, Van Asperen P. Update in paediatric asthma management: where is evidence challenging current practice? J Paediatr Child Health 2013;49:346–52. [PubMed]