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 outcomes of interest were the prevalence of comorbidities, exposure to neuropathic pain-related medications (le, 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 mg/d; pregabalin, >= 150 mg/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 opiolds (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 opiold prescriptions (P = 0.016). Use of any opioid decreased significantly from pretreatment to follow-up in those prescribed pregabalin (P = 0.005), particularly in those who received >= 2 opioid 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 prescribedpregabalin received a prescription for a therapeutic dose. (Clin Ther. 2007;29:1655-1670) Copyright (c) 2007 Excerpta Medica, Inc.