Medication dosing patterns associated with duloxetine and pregabalin among patients with fibromyalgia

To examine medication dosing patterns of duloxetine and pregabalin among patients with fibromyalgia.

From a large US administrative claims database, commercially insured fibromyalgia patients aged 18-64 who initiated duloxetine or pregabalin in 2006 were selected. Initiation was defined as a 90-day medication gap, with the dispense date of the first initiation as the index date. All patients selected had continuous enrollment over the 12-month pre- and post-index periods, and were classified into the duloxetine or pregabalin cohorts based on their index agent. Initial daily dose, average daily dose over the 12-month post-index period, mean and median daily doses and daily costs of each of the first 12 prescriptions were examined for both the duloxetine and pregabalin cohorts.

Both the duloxetine (n = 3773) and pregabalin (n = 4189) cohorts had a mean age of 50 years (median age: 52 vs. 53). The average initial daily dose was 55.7 mg for duloxetine and 161.5 mg for pregabalin. Over the 12-month post-index period, the average daily dose per patient was 55.6 mg for duloxetine and 195.7 mg for pregabalin. The average daily doses for the first 12 duloxetine prescriptions ranged 55.7-60.3 mg, with the mean daily costs between $3.77 and $4.59. For the first 12 pregabalin prescriptions, the average daily dose increased from 161.5 mg to 282.4 mg, while the average daily costs ranged between $4.30-4.61.

Among patients with fibromyalgia, duloxetine and pregabalin initiators had different dosing patterns. The average daily dose for duloxetine was relatively stable over time, while pregabalin patients had significant dose increase over the 12-month post-index period.