Initiation of Pregabalin Fails to Reduce Per Patient Prescription Rates and Costs

Minneapolis—The initiation of pregabalin, which is typically prescribed as adjunctive therapy in patients who experience seizures and as relief for neuropathic pain in patients with diabetes, postherpetic neuralgia, or fibromyalgia, correlated with a nearly 50% increase in per patient drug costs during the first 6 months of use. Fewer patients required opioids, but the average opioid dose increased, as did doses for concomitant anticonvulsants. Researchers for the study, which was presented as a poster titled Assessment of Medication Utilization Before and After Pregabalin Utilizing a Pharmacy Claims Data base at the AMCP meeting, were surprised not to see more of a decline in prescriptions and dosing for gabapentin, another anticonvulsant prescribed for seizures and neuropathic pain. The investigative team sought to determine whether pregabalin therapy would affect the use of medications from among 6 therapeutic categories: antianxiety agents; antidepressants; opioids; anti-inflammatory and nonnarcotic analgesics; migraine medications; and anticonvulsants and musculoskeletal agents. In addition to assessing changes in number, type, and doses of drugs used, researchers weighed whether different copayment tiers influenced adherence to pregabalin. They reviewed pharmacy claims for 4 plans, each applying a different copayment structure, and identified patients (n=414) who filled a prescription for pregabalin. Patients’ medical diagnoses were unknown. The analysis incorporated drug claims from the 6-month windows before and after the start of pregabalin. Before initiating pregabalin therapy, patients took an average of 9 to 15 medications; this increased by 1 to 2 prescriptions per patient (not including the pregabalin prescription) in the follow-up period. Product counts were highest for patients enrolled in the plan requiring a $1 copayment per 30-day supply but varied little among the remaining plans, which had respective copayment amounts of $10, $20, and $30. Because anticonvulsants, opioids, and antidepressants were typically the most expensive agents, the research focused primarily on these drug categories. Approximately 50% of patients were using antidepressants prior to the pregabalin index date, and this rate did not change significantly. Investigators did observe minute increases in the use and ingredient cost of antidepressants for 2 plans, however. Although patients added only 1 to 2 medications overall, use of anticonvulsants increased on average by >2 drugs per patient. Investigators described this as an indication of concomitant use of anticonvulsants other than pregabalin. Several patients on gabapentin discontinued this anticonvulsant or took lower doses once they started pregabalin. The most significant decreases were observed in the cohort with a $1 copayment: of the 57% of patients taking gabapentin at baseline, 36% discontinued, and doses fell an average of 31%. The remaining cohorts, in which 16% to 23% of patients were taking gabapentin at baseline, experienced much smaller reductions: between 4% and 10% of patients discontinued gabapentin, and the average dose declined by ≤4%. At the pregabalin index date, between 63% and 80% of plan subscribers were prescribed opioids, which shifted to between 57% and 82% in the follow-up period. All plans showed increases in the average opioid dose and ingredient costs per patient. Medication possession ratios associated with pregabalin use ranged from 0.81 to 0.85, which investigators said was indicative of good adherence. Although the average dose of pregabalin increased in all 4 plans, it remained <300 mg/day at the study’s conclusion. The study was financed and conducted by informedRx, an affiliate of SXC Health Solutions Corp, and a medical outcomes specialist with Pfizer-provided analytical support.