Diffusion into Use of Exenatide for Glucose Control in Diabetes Mellitus: A Retrospective Cohort Study of a New Therapy

Background: Exenatide was approved by the US Food and Drug Administration (FDA) in April 2005 as adjunctive therapy to metformin or a sulfonylurea for the treatment of type 2 diabetes mellitus (DM). Objective: We evaluated whether use of exenatide soon after its approval was consistent with the FDA- approved indications. Methods: We assembled a retrospective cohort of patients with DM using data from a population of employed persons and their dependents, including pharmacy claims and claims for inpatient and outpatient services, provided by i3 Innovus. The data set included patients aged between 18 and 64 years with a diagnosis of DM or a claim for a DM drug from June 1, 2004, to December 31, 2005. Laboratory data were available for a subgroup of patients tested at specific commercial laboratories from June 1, 2003, to December 31, 2005. In addition, we requested data for patients with a diagnosis of obesity, regardless of a diagnosis of DM, to assess early off-label use of this medication. Patients were categorized by DM medication use and by their first fill date for exenatide, and their clinical characteristics were described. Early use was defined as filling a prescription for exenatide in the first 3 months after its approval. For descriptive purposes, we reported the means and percentages for the variables described. Results: The study included data for 206,345 individuals (mean age, 51.3 years), of whom 54.0% were male. Starting in June 2005, prescriptions for exenatide were filled by 3225 (1.6%) individuals. Fifty-three percent of early users were women. Among those who filled a prescription for exenatide, 21.9% were obese, compared with 10.9% to 15.1% of those filling prescriptions for other DM medications. The proportion of patients filling a prescription for exenatide who had not received a prescription for any other DM medication in the preceding year was 14%, suggesting that exenatide was their initial therapy. A prescription for a thiazolidinedione was filled by 29.9% of patients within 60 days of filling a prescription for exenatide. Conclusions: Soon after its approval, exenatide was frequently used as monotherapy or in combination with a thiazolidinedione, neither of which is an FDA- approved indication. The observation that those filling a prescription for exenatide had a higher prevalence of obesity than those receiving prescriptions for other therapies may reflect awareness of the weight-lowering effects of exenatide. (Clin Ther. 2007;29:1784-1794)