Fixed dose combination diabetes medicines - usage in the Australian veteran population

To examine initiation and prescribing patterns of metformin-glibenclamide and metformin-rosiglitazone fixed dose combination products within the Australian veteran population.

A retrospective observational study using Department of Veterans' Affairs pharmacy claims data. We examined overall trends in the utilisation and proportion of patients who had been previously dispensed both, one, or none of the individual ingredient products before initiating combination products.

Of metformin-glibenclamide initiations, 9% involved a switch from metformin and glibenclamide as separate products, while 22% had used neither metformin nor a sulfonylurea. Thirty percent of metformin-rosiglitazone initiations involved a switch from both individual products, while in 10% neither metformin nor thiazolidinedione had been dispensed.

A minority of veterans started taking the combination products after being stabilised on the individual products; many had no prior history of oral hypoglycaemic use. This prescribing may lead to wastage if combination medications are poorly tolerated or, more importantly, may cause adverse events.