How Gabapentin Differs From Pregabalin By Jeffrey Fudin – Sept 2015
More than 85% of patients with neuropathic pain caused by peripheral neuropathy will require pharmacotherapy.
Because the products are so variable, this article compares the pharmacokinetics (PK) and pharmacodynamics (PD) of pregabalin with various gabapentin formulations, and also covers conversion regimens.
Pharmacokinetics of pregabalin and gabapentin
Both pregabalin and gabapentin are antiepileptic medications that bare structural resemblance to gamma-aminobutyric acid (GABA), though neither agent has activity in GABA’s neuronal systems.
Although the exact mechanism of action is somewhat unclear, the drugs’ efficacy in neuropathic pain is linked to their ability to bind to voltage-gated calcium channels in the central nervous system (CNS), specifically to the alpha-2-delta protein.
This binding decreases neurotransmitter release in the CNS as a result of reduced calcium influx through the gated channels.
Gabapentin is indicated as adjunct therapy for partial seizures and postherpetic neuralgia. Pregabalin is indicated for the same uses as gabapentin, plus the management of fibromyalgia and neuropathic pain associated with diabetes, specifically diabetic neuropath
Pregabalin may either have an additional system of absorption or be better transported than gabapentin, as it is almost completely absorbed, while gabapentin is not. In addition, absorption of gabapentin is limited to the small intestine, while pregabalin is absorbed throughout the small intestine and extending to the ascending colon.
Gabapentin is more slowly and variably absorbed, with peak plasma concentrations around 3 hours post-dose. Pregabalin is quickly absorbed, with the maximum rate of absorption being 3 times that of gabapentin. It reaches peak blood concentrations within an hour after ingestion
Gabapentin’s bioavailability for its intended patient population is also more variable than pregabalin’s bioavailability.
Distribution of gabapentin and pregabalin is very similar
Drug-drug interactions are unlikely for both pregabalin and gabapentin
Renal excretion is the major method of both drugs’ elimination from the body.
This is only from the first page of this three-page article, and there is more detailed information in the following pages.