Cost and Consumption of Duloxetine

National Harbor, Maryland—According to a retrospective descriptive analysis of a database of commercially insured US residents, the cost and consumption of duloxetine was lower for patients taking the drug for pain compared with patients taking the medication for major depressive disorder (MDD).

The results were presented at the AAPM meeting during a poster session titled Daily Average Consumption and Pharmacy Costs of Duloxetine in Mood and Pain among US Commercially Insured Patients. Duloxetine, a serotonin and norepinephrine reuptake inhibitor, is approved by the US Food and Drug Administration to treat MDD, generalized anxiety disorder (GAD), diabetic peripheral neuropathic pain (DPNP), fibromyalgia (FM), and chronic musculoskeletal pain. To analyze dosing practices, health plans estimate the average daily patient and/or prescription costs (ADC) and the daily average consumption (DACON) of the medication.

In this study, the authors were interested in examining pharmacy data reports for duloxetine in treating MDD, GAD, DPNP, and FM. They also wanted to determine the ADC and DACON for each indication during a 2-year period. The authors analyzed a database from SDI Health, LLC, a healthcare analytics company based in Plymouth Meeting, Pennsylvania. Patients were included in the study if they received ≥1 prescription for duloxetine from June 2007 through May 2008 or from June 2008 through May 2009. They also had to have been diagnosed ≥1 time for MDD, DPNP, GAD, and/or FM during the 12 months before they were first prescribed duloxetine. In addition, they must have had continuous health plan eligibility for 12 months before their first duloxetine prescription.

The authors calculated DACON by dividing the total units dispensed by the total days of supply for each pill strength. They then averaged the DACONs across pill strengths. They also converted the pills per day to ADC per day using April 2009 wholesale prices. They used the June 2009 wholesale prices as the acquisition costs for the study period. During the June 2007 to May 2008 period, there were 971 indications for MDD, 1201 for GAD, 4439 for DPNP, 8692 for FM, and 8692 for multiple indications. During the June 2008 to May 2009 period, there were 5789 indications for MDD, 1218 for GAD, 1454 for DPNP, 6346 for FM, and 11,141 for multiple indications. In the earlier time period, the DACON was 1.63 for 20 mg duloxetine, 1.62 for 30 mg duloxetine, and 1.19 for 60 mg duloxetine. The ADC was $7.53 for 20 mg duloxetine, $8.41 for 30 mg duloxetine, and $6.18 for 60 mg duloxetine. By indication in that time period, DACON was 1.37 for MDD, 1.24 for GAD, 1.24 for DPNP, and 1.31 for FM. The ADC was $7.04 for MDD, $6.36 for GAD, $6.39 for DPNP, and $6.74 for FM. In the later time period, the DACON was 1.62 for 20 mg duloxetine, 1.57 for 30 mg duloxetine, and 1.22 for 60 mg duloxetine. The ADC was $4.61 for 20 mg duloxetine, $5.18 for 30 mg duloxetine, and $5.18 for 60 mg duloxetine. By indication, during the later time period, DACON was 1.38 for MDD, 1.24 for GAD, 1.27 for DPNP, and 1.30 for FM. The ADC was $7.10 for MDD, $6.36 for GAD, $6.56 for DPNP, and $6.69 for FM.

The authors cited a few study limitations: coding errors may have contributed to incorrect patient assignments and claims; the researchers could not test statistical differences in DACON and ADC across the indications and time because they utilized aggregate pharmacy pills dispensed data; and the study did not include data pertaining to musculoskeletal pain because duloxetine was not approved to treat musculoskeletal pain until 2010.