Pronunciation:

gab-a-PEN-tin en-a-KAR-bil

Brand Names:

• Horizant

Dosage Forms:

• Tablet, Extended Release

Classifications:

Therapeutic—

Analgesic

Pharmacologic—

Gabapentinoid

Chemical—

Gamma Aminobutyric Acid (class)

Uses of This Medicine:

Gabapentin enacarbil is used to treat moderate-to-severe primary Restless Legs Syndrome (RLS). RLS is a neurologic disorder that makes the legs feel uncomfortable. This results in an irresistible feeling of wanting to move your legs to make them comfortable.

Gabapentin enacarbil is also used to manage a condition called postherpetic neuralgia, which is pain that occurs after shingles.

This medicine is available only with your doctor's prescription.

Before Using This Medicine:

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Allergies—

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Children—

Appropriate studies have not been performed on the relationship of age to the effects of gabapentin enacarbil in the pediatric population. Safety and efficacy have not been established.

Older adults—

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of gabapentin enacarbil in the elderly. However, elderly patients are more likely to have age-related kidney problems, which may require caution and an adjustment in the dose for patients receiving gabapentin enacarbil.

Breast-feeding—

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Other medicines—

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Acepromazine
• Alfentanil
• Alprazolam
• Amobarbital
• Anileridine
• Aripiprazole
• Asenapine
• Baclofen
• Benperidol
• Benzhydrocodone
• Bromazepam
• Buprenorphine
• Buspirone
• Butabarbital
• Butorphanol
• Calcifediol
• Calcium Oxybate
• Cannabidiol
• Cannabis
• Carbinoxamine
• Carisoprodol
• Carphenazine
• Chloral Hydrate
• Chlordiazepoxide
• Chlorpromazine
• Chlorzoxazone
• Clobazam
• Clonazepam
• Clorazepate
• Clozapine
• Codeine
• Cyclobenzaprine
• Daridorexant
• Dexmedetomidine
• Diacetylmorphine
• Diazepam
• Dichloralphenazone
• Difenoxin
• Dihydrocodeine
• Diphenhydramine
• Diphenoxylate
• Doxylamine
• Droperidol
• Enflurane
• Esketamine
• Estazolam
• Eszopiclone
• Ethchlorvynol
• Ethopropazine
• Ethylmorphine
• Fentanyl
• Flibanserin
• Fluphenazine
• Flurazepam
• Fluspirilene
• Fospropofol
• Gabapentin
• Halazepam
• Haloperidol
• Halothane
• Hexobarbital
• Hydrocodone
• Hydromorphone
• Hydroxyzine
• Isoflurane
• Ketamine
• Ketazolam
• Ketobemidone
• Lacosamide
• Levocetirizine
• Levorphanol
• Lorazepam
• Loxapine
• Magnesium Oxybate
• Meclizine
• Melperone
• Meperidine
• Mephobarbital
• Meprobamate
• Meptazinol
• Mesoridazine
• Metaxalone
• Methadone
• Methdilazine
• Methocarbamol
• Methohexital
• Methotrimeprazine
• Methylene Blue
• Midazolam
• Molindone
• Moricizine
• Morphine
• Morphine Sulfate Liposome
• Nalbuphine
• Nicomorphine
• Nitrazepam
• Nitrous Oxide
• Olanzapine
• Opium
• Opium Alkaloids
• Orlistat
• Orphenadrine
• Oxazepam
• Oxycodone
• Oxymorphone
• Papaveretum
• Paregoric
• Pentazocine
• Pentobarbital
• Perampanel
• Perazine
• Periciazine
• Perphenazine
• Phenobarbital
• Pimozide
• Piperacetazine
• Pipotiazine
• Piritramide
• Potassium Oxybate
• Prazepam
• Pregabalin
• Primidone
• Prochlorperazine
• Promazine
• Promethazine
• Propofol
• Quazepam
• Quetiapine
• Ramelteon
• Remifentanil
• Remimazolam
• Remoxipride
• Ropeginterferon Alfa-2b-njft
• Secobarbital
• Sertindole
• Sodium Oxybate
• Sufentanil
• Sulpiride
• Suvorexant
• Tapentadol
• Temazepam
• Thiethylperazine
• Thiopental
• Thiopropazate
• Thioridazine
• Tilidine
• Tizanidine
• Tolonium Chloride
• Topiramate
• Tramadol
• Triazolam
• Trifluoperazine
• Trifluperidol
• Triflupromazine
• Trimeprazine
• Zaleplon
• Zolpidem
• Zopiclone
• Zotepine
• Zuranolone

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Aluminum Carbonate, Basic
• Aluminum Hydroxide
• Aluminum Phosphate
• Dihydroxyaluminum Aminoacetate
• Dihydroxyaluminum Sodium Carbonate
• Ginkgo
• Magaldrate
• Magnesium Carbonate
• Magnesium Hydroxide
• Magnesium Oxide
• Magnesium Trisilicate

Other interactions—

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Other medical problems—

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

• Depression, history of or
• Lung or breathing problems (eg, respiratory depression) or
• Mental illness, history of—Use with caution. May make these conditions worse.

• Kidney disease (eg, patients receiving dialysis)—Use with caution. The effects may be increased because of slower removal of the medicine from the body.

• Patients who need to sleep during daytime and remain awake at night—Use is not recommended.

Proper Use of This Medicine:

Take this medicine only as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered. To do so may increase the chance of side effects.

This medicine comes with a Medication Guide. Read and follow the instructions carefully. Ask your doctor if you have any questions.

Swallow the extended-release tablet whole. Do not crush, break, or chew it. It should be taken with food.

For patients with restless legs syndrome: Do not use this medicine if you are required to sleep during the daytime and remain awake at night.

Only use the brand of this medicine that your doctor prescribed. Different brands may not work the same way.

Dosing—

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

• For oral dosage form (extended-release tablets):
  • For restless legs syndrome:
    • Adults—600 milligrams (mg) as a single dose at about 5 PM. Your doctor may adjust your dose as needed and tolerated.
    • Children—Use and dose must be determined by your doctor.
  • For postherpetic neuralgia:
    • Adults—At first, 600 milligrams (mg) once a day taken in the morning for 3 days. Then, your doctor will increase your dose to 600 mg two times a day. Your doctor may adjust your dose as needed and tolerated. However, the dose is usually not more than 1,200 mg per day.
    • Children—Use and dose must be determined by your doctor.

Missed dose—

If you miss a dose of this medicine, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage—

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Precautions While Using This Medicine:

It is very important that your doctor check your progress at regular visits. This will allow your doctor to see if the medicine is working properly and to decide if you should continue to take it.

Gabapentin enacarbil may cause dizziness, drowsiness, or sleepiness. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are not alert. If these side effects are especially bothersome, check with your doctor.

This medicine may cause some people to be agitated, irritable, or display other abnormal behaviors, such as feeling sad or hopeless, getting upset easily, or feeling nervous, restless, or hostile. It may also cause some people to have suicidal thoughts and tendencies or to become more depressed. If you or your caregiver notice any of these side effects, tell your doctor right away.

This medicine may cause respiratory depression, a serious breathing problem that can be life-threatening, when used together with narcotic pain medicines. Check with your doctor right away if you have pale or blue lips, fingernails, or skin, difficult or troubled breathing, or irregular, fast or slow, or shallow breathing.

Check with your doctor right away if you have a fever, rash, swollen, painful, or tender lymph glands in the neck, armpit, or groin, unusual bleeding or bruising, or yellow eyes or skin. These may be symptoms of a serious and life-threatening allergic reaction called drug reaction with eosinophilia and systemic symptoms (DRESS) or multiorgan hypersensitivity.

Do not stop using this medicine without checking with your doctor. Stopping the medicine suddenly may cause seizures. Your doctor may want you to gradually reduce the amount you are taking before stopping it completely.

Do not drink alcohol while you are using this medicine.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Side Effects of This Medicine:

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common

Bloating or swelling of the face, arms, hands, lower legs, or feet

discouragement

feeling sad or empty

irritability

lack of appetite

loss of interest or pleasure

rapid weight gain

tingling of the hands or feet

tiredness

trouble concentrating

Incidence not known

Black, tarry stools

bloody or cloudy urine

changes in behavior

chest pain or discomfort

chills or fever

confusion

difficulty with breathing

dizziness or lightheadedness

fainting

fast heartbeat

nausea or vomiting

painful or difficult urination

rapid, shallow breathing

rash

sore throat

sores, ulcers, or white spots on the lips or in the mouth

swelling of the face, feet, or lower legs

swollen, painful, or tender lymph glands in the neck, armpit, or groin

thoughts of killing oneself

unusual bleeding or bruising

upper right abdominal or stomach pain

yellow eyes and skin

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Lack or loss of strength

sleepiness or unusual drowsiness

Less common

Blurred vision

decreased interest in sexual intercourse

dry mouth

excess air or gas in the stomach or intestines

inability to have or keep an erection

sensation of spinning

weight gain

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

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