THERAPEUTICS

Brands

• Neurontin, Gabarone, Neupentin, Neurostil, Gralise, Horizant (gabapentin enacarbil)

Generic?

• Yes

Class

• Antiepileptic drug (AED)

Commonly Prescribed for

(FDA approved in bold)

• Partial-onset seizures with and without secondary generalization (adjunctive for adults and children 3 years and older)

• Pain associated with post-herpetic neuralgia

• Moderate to severe primary restless legs syndrome (RLS) in adults (gabapentin enacarbil)

• Diabetic neuropathic pain

• Allodynia and hyperalgesia

• Fibromyalgia

• Bipolar disorder

• Generalized anxiety disorder

• Alcohol and drug withdrawal

• Insomnia

• Migraine prophylaxis

• Back pain

• Hot flushes (cancer related, postmenopausal)

• Uremic pruritus

How the Drug Works

• Structural analog of GABA that binds at the α2δ1 subunit of voltage-sensitive calcium channels (CACNA2D1) and reduces calcium influx. Modulates calcium channel function but not as a blocker

• Reduces release of excitatory neurotransmitters (glutamate, norepinephrine, calcitonin gene-related peptide [CGRP])

• Increased plasma serotonin levels

• Inactive at GABA receptors and does not affect GABA uptake or degradation

How Long Until It Works

• Seizures: 2 weeks

• Pain/anxiety: days to weeks

If It Works

• Seizures: goal is the remission of seizures. Continue as long as effective and well tolerated. Consider tapering and slowly stopping after 2 years without seizures, depending on the type of epilepsy

• Pain: goal is reduction of pain. Usually reduces but does not cure pain and there is recurrence off the medication. Consider tapering for conditions that may improve over time, i.e., post-herpetic neuralgia or migraine

If It Doesn't Work

• Increase to highest tolerated dose

• Epilepsy: consider changing to another agent, adding a second agent, using a medical device, or a referral for epilepsy surgery evaluation. When adding a second agent, keep drug interactions in mind

• Pain: if not effective in 2 months, consider stopping or using another agent