Dosing Pattern Comparison Between Duloxetine and Pregabalin among Patients with Diabetic Peripheral Neuropathic Pain

Objective:  To compare medication dosing patterns of duloxetine and pregabalin among patients with diabetic peripheral neuropathic pain (DPNP). Methods:  Applying a retrospective cohort study design on a large U.S. healthcare claims database, we examined the dosing patterns of duloxetine and pregabalin among commercially insured patients with DPNP aged 18 to 64 who initiated (a 90-day medication gap) duloxetine or pregabalin therapy in 2006. Selected patients had continuous enrollment during the 12-month pre- and post-index periods. The index mediation was used to classified individuals into the duloxetine or pregabalin cohorts. Initial daily dose, average daily dose over the first post-index year, and average daily dose of the first several prescriptions were estimated and compared across the cohorts. Results:  The study sample included 828 duloxetine and 1934 pregabalin-treated patients with a mean age of 50 years. Cardiovascular diseases, neuropathic pain other than DPNP, osteoarthritis, and diabetic retinopathy were the most common comorbid conditions. The average initial daily doses were 54.3 and 171.8 mg for duloxetine and pregabalin, respectively. The average daily dose over the first post-index year was 55.2 mg for duloxetine and 173.8 mg for pregabalin. The average daily dose for the first 10 duloxetine prescriptions ranged between 54.3 and 61.9 mg, but increased from 171.8 to 264.3 mg for pregabalin. Conclusions:  The commercially insured patients with DPNP who initiated duloxetine or pregabalin therapy had different dosing patterns. The average daily dose for duloxetine was relatively stable over time, while pregabalin-treated patients had significant dose increase over the 12-month post-index period.