A Retrospective Evaluation of the Use of Gabapentin and Pregabalin in Patients with Postherpetic Neuralgia in Usual-Care Settings

Background: Both gabapentin and pregabalin are approved for the management of postherpetic neuralgia (PHN), although dosing and pharmacokinetic differences between these medications may affect their use in actual practice. Objectives: This study was conducted to characterize the use of gabapentin and pregabalin in the management of PHN in clinical practice, with a specific focus on the doses actually prescribed and changes in the use of other neuropathic pain-related medications after the initiation of gabapentin or pregabalin. Methods: The PharMetrics Patient-Centric Database was used to identify patients with PHN who were newly prescribed gabapentin or pregabalin between September 1, 2005, and March 31, 2006. The out-comes of interest were the prevalence of comorbidities, exposure to neuropathic pain-related medications (ie, the proportions of patients receiving ≥1 prescription for these medications in the 6-month periods before and after the date of the first gabapentin or pregabalin prescription), and attainment of therapeutic dose levels (gabapentin, ≥1800 rag/d; pregabalin, ≥150 rag/d). Results: The database search identified 151 patients with PHN who were newly prescribed gabapentin (57.0% female; mean [SD] age, 55.8 [11.3] years) and 100 patients who were newly prescribed pregabalin (62.0% female; mean age, 52.8 [9.4] years). The prevalence of comorbidities did not differ significantly between recipients of prescriptions for gabapentin or pregabalin, with the exception of hyperlipidemia, which was more prevalent in those prescribed gabapentin (33.8% vs 22.0%, respectively; P = 0.044), and depression, which was more prevalent in those prescribed pregabalin (12.0% vs 4.6%, respectively; P = 0.031). In the pretreatment period, those who were prescribed pregabalin had significantly greater use of long-acting opioids (P = 0.005), anticonvulsants (P < 0.001), selective norepinephrine reuptake inhibitors (P < 0.001), and the lidocaine 5% patch (P = 0.005) compared with those prescribed gabapentin. Use of any opioid increased from pretreatment to follow-up in those prescribed gabapentin, significantly so in those who received ≥2 opioid prescriptions (P = 0.016). Use of any opioid decreased significantly from pre-treatment to follow-up in those prescribed pregabalin (P = 0.005), particularly in those who received >2 opi-old prescriptions (P = 0.004). Tramadol use decreased significantly in those prescribed gabapentin (P = 0.045), and anticonvulsant use decreased significantly in those prescribed pregabalin (P = 0.004). Among patients prescribed gabapentin or pregabalin who received 1 prescription, 2 consecutive prescriptions, and ≥3 consecutive prescriptions, a greater proportion of those prescribed pregabalin attained therapeutic dose levels by their first, second, and third consecutive prescriptions compared with those prescribed gabapentin (69.0% vs 3.5%, respectively [P < 0.001]; 71.4% vs 21.7% [P < 0.001]; and 89.3% vs 46.2% [P < 0.001], respectively). Conclusions: In these patients with PHN in the usual-care setting, opioid use increased after the initiation of gabapentin and decreased after the initiation of pregabalin. Few of those prescribed gabapentin received a prescription for a therapeutic dose, whereas a greater proportion of patients who were prescribed pregabalin received a prescription for a therapeutic dose.