Horizant (gabapentin enacarbil)

Generic name: gabapentin enacarbil
Brand name: Horizant
Drug class: Gamma-aminobutyric acid analogs

Horizant (gabapentin enacarbil) is a prescription medicine used to treat adults with restless legs syndrome and pain from damaged nerves. It affects chemicals and nerves in the body that are involved in the cause of some types of pain.

Horizant is used in adults to treat nerve pain (postherpetic neuralgia) caused by herpes virus or shingles (herpes zoster).

Horizant is also used to treat restless legs syndrome (RLS).

Use only the brand and form of gabapentin your doctor has prescribed. Check your medicine each time you get a refill to make sure you receive the correct form.


Some people have thoughts about suicide while taking this medicine. Stay alert to changes in your mood or symptoms. Report any new or worsening symptoms to your doctor.

Do not stop using Horizant suddenly, even if you feel fine.

Before taking this medicine

You should not use Horizant if you are allergic to gabapentin.

To make sure Horizant is safe for you, tell your doctor if you have ever had:

  • lung disease, such as chronic obstructive pulmonary disease (COPD);
  • kidney disease (or if you are on dialysis);
  • diabetes;
  • depression, a mood disorder, or suicidal thoughts or actions;
  • a seizure (unless you take gabapentin to treat seizures);
  • liver disease;
  • heart disease; or
  • (for patients with RLS) if you are a day sleeper or work a night shift.

Some people have thoughts about suicide while taking this medicine. Your doctor should check your progress at regular visits. Your family or other caregivers should also be alert to changes in your mood or symptoms.

It is not known whether this medicine will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

Gabapentin enacarbil can pass into breast milk, but effects on the nursing baby are not known. Ask your doctor about any risk.

How should I take Horizant?

Take Horizant exactly as prescribed by your doctor. Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Do not cut, crush, chew, or break an extended-release Horizant tablet. Swallow the tablet whole.

If your doctor changes your brand, strength, or type of gabapentin, your dosage needs may change. Ask your pharmacist if you have any questions about the new kind of gabapentin you receive at the pharmacy.

Do not stop using Horizant suddenly, even if you feel fine. Follow your doctor's instructions about tapering your dose.

This medicine can cause unusual results with certain medical tests. Tell any doctor who treats you that you are using gabapentin enacarbil.

Store Horizant extended-release tablets at room temperature away from light and moisture.

Dosing information

Usual Adult Dose of Horizant for Postherpetic Neuralgia:

The recommended dosage is 600 mg orally 2 times a day. Therapy should be initiated at a dose of 600 mg orally in the morning for 3 days of therapy, then increased to 600 mg 2 times a day (1200 mg/day) on day four.
Gabapentin enacarbil extended release tablets available under the trade name Horizant and gabapentin are not interchangeable.
Use: Postherpetic neuralgia

Usual Adult Dose of Horizant for Restless Legs Syndrome:

600 mg orally once daily with food at about 5 PM. A dose of 1,200 mg once daily provided no additional benefit compared with the 600-mg dose, but caused an increase in adverse reactions.
Use: For the treatment of moderate-to-severe primary Restless Legs Syndrome (RLS) in adults

What happens if I miss a dose?

Take the missed dose as soon as you remember. Be sure to take the medicine with food. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What to avoid

Avoid driving or hazardous activity until you know how gabapentin enacarbil will affect you. Your reactions could be impaired.

Drinking alcohol with this medicine can cause side effects.

Horizant side effects

Get emergency medical help if you have signs of an allergic reaction to Horizant: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Seek medical treatment if you have a serious drug reaction that can affect many parts of your body. Symptoms may include: skin rash, fever, swollen glands, muscle aches, severe weakness, unusual bruising, upper stomach pain, or yellowing of your skin or eyes. This reaction may occur several weeks after you began using Horizant.

Report any new or worsening symptoms to your doctor, such as: mood or behavior changes, anxiety, panic attacks, trouble sleeping, or if you feel impulsive, irritable, agitated, hostile, aggressive, restless, hyperactive (mentally or physically), depressed, or have thoughts about suicide or hurting yourself.

Call your doctor at once if you have:

  • weak or shallow breathing;
  • blue-colored skin, lips, fingers, and toes;
  • confusion, extreme drowsiness or weakness;
  • problems with balance or muscle movement;
  • unusual or involuntary eye movements; or
  • increased seizures.

Gabapentin can cause life-threatening breathing problems. A person caring for you should seek emergency medical attention if you have slow breathing with long pauses, blue colored lips, or if you are hard to wake up. Breathing problems may be more likely in older adults or in people with COPD.

Some side effects are more likely in children taking gabapentin. Contact your doctor if the child taking this medicine has any of the following side effects:

  • changes in behavior;
  • memory problems;
  • trouble concentrating; or
  • acting restless, hostile, or aggressive.

Common Horizant side effects may include:

  • headache;
  • dizziness, drowsiness, tiredness;
  • problems with balance or eye movements; or
  • (in children) fever, nausea, vomiting.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Horizant?

Taking Horizant with other drugs that make you sleepy can worsen this effect. Ask your doctor before taking a sleeping pill, narcotic medication, muscle relaxer, or medicine for anxiety, depression, or seizures.

Other drugs may interact with gabapentin enacarbil, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.