Which medications in the drug class Anticonvulsants are used in the treatment of Postherpetic Neuralgia?

Updated: Mar 06, 2018
  • Author: W Alvin McElveen, MD; Chief Editor: Robert A Egan, MD  more...
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These agents are used to manage severe muscle spasms and provide sedation in neuralgia. They have central effects on pain modulation. Prescribing information for gabapentin products (ie, Neurontin, Gralise, Horizant) describe a statistical improvement in pain scores (ie, a decrease by at least 50% from baseline) compared with placebo when treated for postherpetic neuralgia.

In October 2017, FDA approved Lyrica CR (pregabalin extended-release tablets), a once-daily treatment for the management of neuropathic pain associated with diabetic peripheral neuropathy (pDPN) and the management of postherpetic neuralgia (PHN). The approval was based on data from a randomized placebo-controlled trial conducted in 801 patients with PHN. The trial included a 6-week single-blind, dose optimization phase followed by a 13-week double-blind phase. Compared to placebo, more patients in the Lyrica CR group experienced at least a 50% improvement in pain intensity (73.6% vs. 54.6%). 

Pregabalin (Lyrica, Lyrica CR)

Approved by FDA for use in PHN. Freynhagen et al describe a statistically significant reduction in mean pain score and in pain-related sleep interference compared with placebo. Pregabalin binds with high affinity to alpha2-delta subunit of voltage-gaited calcium channels, thereby reducing excitatory neurotransmitters. Has half-life of approximately 6 h and is eliminated by renal excretion. Decrease in creatinine clearance results in decrease elimination and, therefore, increase in plasma concentration. Peak plasma concentration occurs at one and one half hours after oral intake. Bioavailability is 90%. Following repeated dosing, steady state concentration is achieved at 24-48 h. Can be taken with or without food.

The extend-release formulation is available in 82.5mg, 165mg, and 330mg tablets strength. It is administered once daily after an evening.

Gabapentin (Neurontin, Gralise)

This medication has been approved by the FDA for the treatment of PHN. Has properties common to other anticonvulsants and antineuralgic effects. Exact mechanism of action is not known. Structurally, gabapentin is related to GABA, but it does not interact with GABA receptors. Believed to have a binding site at the alpha 2-delta protein, an auxiliary subunit of voltage-gaited calcium channels. In the rat brain, binding is localized on neuronal dendritic areas. Relevance of these observations to treatment of PHN is not known.

Gabapentin enacarbil (Horizant)

Gabapentin prodrug that provides a longer duration of action compared with gabapentin. Structurally related to neurotransmitter GABA, but has no effect on GABA binding, uptake, or degradation. The mechanism for analgesic activity is unknown. Approved by the FDA for PHN.

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