Pregabalin versus gabapentin: Pregabalin, like gabapentin, is an amino acid derivative of gamma-amino butyric acid (GABA analogue).1,2 Pregabalin is the pharmacologically active S-enantiomer of 3-aminomethyl-5-methyl-hexanoic acid, and has a similar pharmacological profile to gabapentin.1 These agents are part of a unique class that have a high affinity to the alpha-2-delta protein in the CNS.3,4,5 Both agents have been shown to be effective for neuropathic pain disorders, however, only prebabalin has been FDA approved for both the management of diabetic peripheral neuropathy and post herpetic neuralgia.3,6,7 Pregabalin has been shown in studies to provide equivalent efficacy to gabapentin, however, at much lower doses.3,5 Because lower dosages can be used to treat neuropathic pain, it is likely that pregabalin will be associated with fewer dose-related adverse events.3,5Part of the reason why pregabalin requires lower dosages is that it has a much higher bioavailability (90% versus 33-66%) and is rapidly absorbed (peak: 1 hr). Also, plasma concentrations increase linearly with increasing dose.3 This is not true with gabapentin. Gabapentin is slowly absorbed (peak: 3 to 4 hours post-dose) and more importantly, plasma concentrations have been found to have a non-linear relationship to increasing doses. Pregabalin has been found to have distinct pharmacokinetic advantages over gabapentin.3 Pregabalin has shown greater potency than gabapentin in pain and seizure disorders.6 J. Fehrenbacher et al stated that pregabalin has been shown to have greater analgesic activity in rodent models of neuropathic pain.2 Further, D. Wesche et al noted that pregabalin is approximately 2.5 times more potent than gabapentin based on plasma concentrations.
