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Generic Name: gabapentin enacarbil
Date of Approval: April 6, 2011
Company: GlaxoSmithKline and XenoPort, Inc.
Treatment for: Restless Legs Syndrome; Postherpetic Neuralgia

FDA Approves Horizant

The U.S. Food and Drug Administration (FDA) has approved Horizant (gabapentin enacarbil) Extended-Release Tablets for the treatment of moderate-to-severe primary Restless Legs Syndrome in adults. Horizant is not recommended for patients who are required to sleep during the daytime and remain awake at night. The efficacy of Horizant in the treatment of patients with moderate-to-severe primary Restless Legs Syndrome was demonstrated in two 12-week clinical trials in adults. It is the first medication in its class to be approved for the treatment of moderate-to-severe primary Restless Legs Syndrome. Horizant is also approved for the management of postherpetic neuralgia (PHN) in adults.

Horizant Medication Guide

Read this Medication Guide before you start taking Horizant and each time you get a refill. There may be new information. This information does not take the place of talking to your healthcare provider about your medical condition or treatment.

Important information

Horizant can cause serious side effects:

  1. Do not drive after taking your dose of Horizant until you know how Horizant affects you, including the morning after you take your dose.

    Do not operate heavy machinery or do other dangerous activities until you know how Horizant affects you. Horizant can cause sleepiness, dizziness, slow thinking, and can affect your coordination. Ask your healthcare provider when it would be okay to do these activities.

  2. Horizant may cause suicidal thoughts or actions in a very small number of people, about 1 in 500.

    Call a healthcare provider right away if you have any of these symptoms, especially if they are new, worse, or worry you:

    • thoughts about suicide or dying
    • attempt to commit suicide
    • new or worse depression
    • new or worse anxiety
    • feeling agitated
    • new or worse restlessness
    • panic attacks
    • new or worse trouble sleeping (insomnia)
    • new or worse irritability
    • acting aggressive, being angry, or violent
    • acting on dangerous impulses
    • an extreme increase in activity and talking (mania)
    • other unusual changes in behavior or mood

    How can I watch for early symptoms of suicidal thoughts and actions?

    • Pay attention to any changes, especially sudden changes, in mood, behaviors, thoughts, or feelings.
    • Keep all follow-up visits with your healthcare provider as scheduled.
    • Call your healthcare provider between visits as needed, especially if you are worried about symptoms.

    Do not stop Horizant without first talking to a healthcare provider. Suicidal thoughts or actions can be caused by things other than medicines. If you have suicidal thoughts or actions, your healthcare provider may check for other causes.

What is Horizant?

Horizant is a prescription medicine used to treat adults with moderate-to-severe primary Restless Legs Syndrome (RLS).

Horizant is not for people who need to sleep during the daytime and need to stay awake at night.

Horizant is not the same medicine as gabapentin (for example, Neurontin or Gralise) and should not be used in its place.

It is not known if Horizant is safe and effective in children.

Before taking this medicine

Before taking Horizant, tell your healthcare provider if you:

  • have or have had kidney problems or are on hemodialysis.
  • have or have had depression, mood problems, or suicidal thoughts or behavior.
  • if you are pregnant or plan to become pregnant. It is not known if Horizant will harm your unborn baby. Talk to your healthcare provider if you are pregnant or plan to become pregnant while taking Horizant. You and your healthcare provider will decide if you should take Horizant while you are pregnant.
  • are breastfeeding or plan to breastfeed. Your body turns Horizant into another drug (gabapentin) that passes into your milk. It is not known if this can harm your baby. You and your healthcare provider should decide if you will take Horizant or breastfeed.

Tell your healthcare provider about all the medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements.

Know the medicines you take. Keep a list of them and show it to your healthcare provider and pharmacist when you get a new medicine.

How should I take Horizant?

  • Take Horizant exactly as your healthcare provider tells you to take it.
  • Take Horizant one time each day with food around 5 PM. If you miss your dose, wait and take your usual dose the next day around 5 PM.
  • Take Horizant tablets whole. Do not cut, crush, or chew your tablet.
  • If you take too much Horizant, call your healthcare provider or go to the nearest hospital emergency room right away.

What should I avoid?

  • Do not take other medicines that make you sleepy or dizzy while taking Horizant without first talking with your healthcare provider. Taking Horizant with medicines that cause sleepiness or dizziness may make your sleepiness or dizziness worse.
  • Do not take other gabapentin drugs (for example, Neurontin or Gralise) while you take Horizant.

Horizant side effects

See Important information about Horizant

The most common side effects of Horizant include:

  • sleepiness
  • dizziness

Tell your healthcare provider if you have any side effect that bothers you or that does not go away.

These are not all the possible side effects of Horizant. For more information, ask your healthcare provider or pharmacist.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

See also: Side effects (in more detail)

How should I store Horizant?

  • Store Horizant between 59° and 86°F (15° and 30°C).
  • Keep Horizant dry and away from moisture.
  • Keep Horizant tightly closed in the bottle provided to you. Do not remove any moisture control packs that may come in the bottle.

Keep Horizant and all medicines out of the reach of children.

General Information about the safe and effective use of Horizant

Medicines are sometimes prescribed for purposes other than those listed in a Medication Guide. Do not use Horizant for a condition for which it was not prescribed. Do not give Horizant to other people, even if they have the same symptoms that you have. It may harm them.

This Medication Guide summarizes the most important information about Horizant. If you would like more information, talk with your healthcare provider.

You can ask your healthcare provider or pharmacist for information about Horizant that was written for healthcare professionals.

For more information about Horizant, go to or call 1-888-825­5249.

What are the ingredients in Horizant?

Active ingredients: gabapentin enacarbil

Inactive ingredients: colloidal silicon dioxide, dibasic calcium phosphate dihydrate, glyceryl behenate, magnesium stearate, sodium lauryl sulfate, and talc.