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Surprising Trends in the Use of Antidiabetic Drugs

Researchers track data on antidiabetic prescriptions dispensed from retail pharmacies in the US and note some interesting prescribing patterns. What is the most antidiabetic drug dispensed?…

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Despite the ability of nonpharmacological methods such as lifestyle interventions and bariatric surgery to improve type 2 diabetes outcomes, most patients require pharmaceutical products to manage this disease state. Over the last ten years, many new drugs have been introduced to the market, including an amylin analog, GLP-1 agonists, DPP-4 inhibitors, a bile acid sequestrant, a dopamine agonist, and the SGLT-2 inhibitors. In recent years, new safety concerns regarding existing drugs have also emerged. Chief among these is rosiglitazone and its associated CV risk. A study by Hampp, C. et al. was conducted to observe how these changes to the market affect trends in prescription antidiabetic drug use.

The data for this study was obtained from the IMS Health Vector One National and Total Patient Tracker for the years 2003-2012. This database tracks drugs dispensed from outpatient retail pharmacies and is able to obtain prescription data from two-thirds of retail pharmacies in the US. Using this data, researchers were able to obtain the annual number of prescriptions dispensed for each class of antidiabetic drug. The Encuity Research Treatment Answers database was also used to observe concomitant use of antidiabetic drugs for the year 2012. This database obtains its data from a survey of more than 3,200 office-based physicians across the US who report all patient activity.

Results showed a 42.9% increase in the number of adults filling antidiabetic drug prescriptions from 2003 to 2012. 78.4% of the prescriptions filled for antidiabetic drugs in 2012 were for noninsulin products. About 1 in every 2 prescriptions were for metformin, and more than ¼ of the total prescriptions were for sulfonylureas (mostly glipizide, glimepiride, and glyburide). 44.9% of metformin use was for monotherapy, while 22.1% was with concomitant use of sulfonylureas, 22.0% was with concomitant use of DPP-4 inhibitors, and 9.7% was with concomitant use of long-acting insulin. Regarding incretin mimetic drugs, DPP-4 inhibitors dominated the market. GLP-1 agonists were also widely used, with liraglutide being the most popular in this class, possibly because it only needs to be injected once a day. Pramlintide and bromocriptine, two other new drugs to the market, were seen infrequently. Though several combination products have come to market in recent years, use of these products declined. In 2004, 15% of treatment visits were associated with oral combination products. In 2012, however, only 6.7% of noninsulin antidiabetic prescriptions were for combination products. Use of rosiglitazone has decreased substantially since studies showing its association with CV events and the FDA putting restrictions on its use in 2011. This study found that 12,597 rosiglitazone-containing products were dispensed in 2012, with <1,000 of these dispensed from a retail pharmacy. These results show that most of these were therefore dispensed from a mail-order pharmacy. Pioglitazone-containing products, however, were much more common, with 6.8 million prescriptions dispensed in 2012. This number, though, is only half of that dispensed in 2008, when pioglitazone reached its peak use. This is somewhat surprising as a generic form of this medication was released in 2012, showing the impact of safety concerns on prescribing habits.

This study shows a steady increase in the number of patients taking antidiabetic drugs, as well as the number of prescriptions dispensed from retail pharmacies. It also showed the important role that metformin plays in the management of diabetes, with 62.7% of patients taking antidiabetic drugs using single-ingredient metformin. The analysis of concomitant use of antidiabetic drugs, however, showed that only one-half to two-thirds of patients using sulfonylureas, DPP-4 inhibitors, thiazolidinediones, and GLP-1 analogs were also using metformin concomitantly. This goes against current guidelines which recommend continuing metformin use when adding other noninsulin antidiabetic medications, unless metformin is contraindicated or not well-tolerated. Future research as to why metformin is not used more often with second-line therapies would be beneficial. Also, now that the FDA has removed restrictions on the use of rosiglitazone, research may show different trends in the use of rosiglitazone and pioglitazone.

Practice Pearls:
  • 1/3-1/2 of noninsulin antidiabetic drug use was not accompanied with metformin, despite treatment guideline recommendations.
  • Rosiglitazone use was almost negligible in 2012 due to restrictions put on it by the FDA. Pioglitazone use also decreased to half of its peak level in 2008.
  • Use of oral combination products decreased substantially since 2004.

Hampp, C. et al. “Use of Antidiabetic Drugs in the U.S., 2003-2012” Diabetes Care. 2014; 38: 8p.