What is gabapentin?

gab-a-PEN-tin

Commonly used brand name(s)

In the U.S.

FusePaq Fanatrex
Gabarone
Gralise
Neurontin

Available Dosage Forms:

Tablet
Capsule
Suspension
Solution

Therapeutic Class: Anticonvulsant

Chemical Class: Gamma Aminobutyric Acid (class)

Uses For gabapentin

Gabapentin is used to help control partial seizures (convulsions) in the treatment of epilepsy. gabapentin cannot cure epilepsy and will only work to control seizures for as long as you continue to take it.

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

Gabapentin works in the brain to prevent seizures and relieve pain for certain conditions in the nervous system. It is not used for routine pain caused by minor injuries or arthritis. Gabapentin is an anticonvulsant.

gabapentin is available only with your doctor's prescription.

Once a medicine has been approved for marketing for a certain use, experience may show that it is also useful for other medical problems. Although this use is not included in product labeling, gabapentin is used in certain patients with the following medical condition:

Diabetic peripheral neuropathy.

Before Using gabapentin

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 gabapentin, the following should be considered:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to gabapentin 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.

Pediatric

Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of gabapentin for treating partial seizures in children. However, safety and efficacy have not been established in children younger than 3 years of age.

Appropriate studies have not been performed on the relationship of age to the effects of gabapentin for treating postherpetic neuralgia in children. Safety and efficacy have not been established.

Geriatric

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of gabapentin in the elderly. However, elderly patients are more likely to have unwanted effects (eg, problems with balance or walking, swelling in the feet or legs) and age-related kidney problems, which may require caution and an adjustment in the dose for patients receiving gabapentin.

Pregnancy

Pregnancy Category Explanation All Trimesters C Animal studies have shown an adverse effect and there are no adequate studies in pregnant women OR no animal studies have been conducted and there are no adequate studies in pregnant women.

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.

Interactions with 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 gabapentin, 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 gabapentin 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.

Ketorolac
Orlistat

Using gabapentin 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
Morphine
Morphine Sulfate Liposome

Interactions with Food/Tobacco/Alcohol

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. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Proper Use of gabapentin

Take gabapentin 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.

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

If you are using Gralise® tablets:

These should be taken with the evening meal.
Swallow the tablet whole. Do not crush, break, or chew it.

For patients with epilepsy who take gabapentin three times per day, do not allow more than 12 hours to pass between any 2 doses. The medicine works best if a constant amount is in the blood.

Neurontin® capsules, tablets, and solution may be taken with or without food.

You may break the scored Neurontin® tablets into two pieces, but make sure you use the second half of the tablet as the next dose. Do not use the half-tablet if the whole tablet has been cut or broken after 28 days. Ask your doctor or pharmacist if you have any questions.

Swallow the capsule whole with plenty of water. Do not open, crush, or chew it.

Measure the oral liquid using a marked measuring spoon, oral syringe, or medicine cup. The average household teaspoon may not hold the right amount of liquid.

If you take an antacid that contains aluminum or magnesium, wait at least 2 hours before taking gabapentin. Some examples of these antacids are Di-Gel®, Gaviscon®, Gelusil®, Maalox® and Mylanta®.

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

Dosing

The dose of gabapentin 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 gabapentin. 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 forms (capsules, liquid, and tablets):
- For epilepsy:
  - Adults and children 12 years of age and older—At first, 300 milligrams (mg) three times per day. Your doctor may adjust your dose as needed. However, the dose is usually not more than 2400 mg per day.
  - Children 3 to 11 years of age—Dose is based on body weight and must be determined by your doctor. The starting dose is 10 to 15 milligrams (mg) per kilogram (kg) of body weight per day and divided in 3 doses. Your doctor may adjust your dose as needed.
  - Children younger than 3 years of age—Use and dose must be determined by your doctor.
- For postherpetic neuralgia:
  - Adults— At first, 300 milligrams (mg) as a single dose in the evening. Your doctor may adjust your dose as needed. However, the dose is usually not more than 1800 mg per day.
  - Children—Use and dose must be determined by your doctor.

Missed Dose

If you miss a dose of gabapentin, take it as soon as possible. However, if it is almost time for your next dose, 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.

You should store the Neurontin® oral liquid in the refrigerator. Do not freeze.

Precautions While Using gabapentin

It is very important that your doctor check your progress at regular visits, especially in the first few months if you have epilepsy. This will allow your doctor to see if the medicine is working properly and to decide if you should continue to take it.

These may be cause serious allergic reactions that may involve multiple organs, such as your liver or kidneys. Check with your doctor right away if you or your child have more than one of the following symptoms: fever, rash, swollen, painful, or tender lymph glands in the neck, armpit, or groin, unusual bleeding or bruising, or yellow eyes or skin.

Gabapentin may cause vision changes, clumsiness, unsteadiness, dizziness, drowsiness, sleepiness, or trouble with thinking. Make sure you know how you react to gabapentin before you drive, use machines, or do anything else that could be dangerous if you are not alert, well-coordinated, or able to think or see well. If these side effects are especially bothersome, check with your doctor.

gabapentin 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, your child, or your caregiver notice any of these side effects, tell your doctor right away.

gabapentin will add to the effects of alcohol and other CNS depressants (medicines that make you drowsy or less alert). Some examples of CNS depressants are antihistamines or medicine for hay fever, allergies, or colds, sedatives, tranquilizers, or sleeping medicines, prescription pain medicine or narcotics, other medicines for seizures (eg, barbiturates), muscle relaxants, or anesthetics, including some dental anesthetics. Check with your medical doctor or dentist before taking any of the above while you or your child are using gabapentin.

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

Make sure any doctor or dentist who treats you knows that you are using gabapentin. gabapentin may affect the results of certain medical tests.

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.

gabapentin Side Effects

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

Clumsiness or unsteadiness
continuous, uncontrolled, back-and-forth, or rolling eye movements

More common in children

Aggressive behavior or other behavior problems
anxiety
concentration problems and change in school performance
crying
depression
false sense of well-being
hyperactivity or increase in body movements
rapidly changing moods
reacting too quickly, too emotional, or overreacting
restlessness
suspiciousness or distrust

Less common

Black, tarry stools
chest pain
chills
cough
depression, irritability, or other mood or mental changes
fever
loss of memory
pain or swelling in the arms or legs
painful or difficult urination
shortness of breath
sore throat
sores, ulcers, or white spots on the lips or in the mouth
swollen glands
unusual bleeding or bruising
unusual tiredness or weakness

Incidence not known

Abdominal or stomach pain
blistering, peeling, or loosening of the skin
clay-colored stools
coma
confusion
convulsions
dark urine
decreased urine output
diarrhea
dizziness
fast or irregular heartbeat
headache
increased thirst
itching or skin rash
joint pain
large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
loss of appetite
muscle ache or pain
nausea
red skin lesions, often with a purple center
red, irritated eyes
unpleasant breath odor
vomiting of blood
yellow eyes or 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

Blurred vision
cold or flu-like symptoms
delusions
dementia
hoarseness
lack or loss of strength
lower back or side pain
swelling of the hands, feet, or lower legs
trembling or shaking

Less common or rare

Accidental injury
appetite increased
back pain
bloated or full feeling
body aches or pain
burning, dry, or itching eyes
change in vision
change in walking and balance
clumsiness or unsteadiness
congestion
constipation
cough producing mucus
decrease in sexual desire or ability
difficulty with breathing
dryness of the mouth or throat
earache
excess air or gas in the stomach or intestines
excessive tearing
eye discharge
feeling faint, dizzy, or lightheadedness
feeling of warmth or heat
flushed, dry skin
flushing or redness of the skin, especially on the face and neck
frequent urination
fruit-like breath odor
impaired vision
incoordination
increased hunger
increased sensitivity to pain
increased sensitivity to touch
increased thirst
indigestion
noise in the ears
pain, redness, rash, swelling, or bleeding where the skin is rubbed off
passing gas
redness or swelling in the ear
redness, pain, swelling of the eye, eyelid, or inner lining of the eyelid
runny nose
sneezing
sweating
tender, swollen glands in the neck
tightness in the chest
tingling in the hands and feet
trouble sleeping
trouble swallowing
trouble thinking
twitching
unexplained weight loss
voice changes
vomiting
weakness or loss of strength
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.

How to use gabapentin?

Usual Adult Dose for Epilepsy

Initial dose: 300 mg orally on day one, 300 mg orally twice a day on day two, then 300 mg orally 3 times a day on day three.
Maintenance dose: 900 to 1800 mg orally in 3 divided doses. If necessary, the dose may be increased using 300 mg or 400 mg capsules three times a day up to 1800 mg/day. Dosages up to 2400 mg/day have been well tolerated in long-term clinical studies. Doses of 3600 mg/day have also been administered to a small number of patients for a relatively short duration, and have been well tolerated. The maximum time between doses in the three times a day schedule should not exceed 12 hours.

The safety and effectiveness of gabapentin available under the trade name Gralise (R) or Horizant (R) in patients with epilepsy has not been studied.

Usual Adult Dose for Postherpetic Neuralgia

Initial dose: 300 mg orally on day one, 300 mg orally twice a day on day two, then 300 mg orally 3 times a day on day three.

The dose may be titrated up as needed for pain relief to a daily dose of 1800 mg.
Maintenance dose: 900 to 1800 mg orally in 3 divided doses.

Efficacy was demonstrated in clinical studies over a range of 1800 mg/day to 3600 mg/day. However, no additional benefit was demonstrated from the use of doses over 1800 mg/day.

Gabapentin available under the trade name Gralise (R):

Maintenance dose: Gralise (R) should be titrated to 1800 mg orally once daily with the evening meal.

Recommended titration schedule:
Day 1: 300 mg orally with the evening meal
Day 2: 600 mg orally with the evening meal
Days 3 through 6: 900 mg orally with the evening meal
Days 7 through 10: 1200 mg orally with the evening meal
Days 11 through 14: 1500 mg orally with the evening meal
Day 15: 1800 mg orally with the evening meal

Gralise (R) is not interchangeable with other gabapentin products because of differing pharmacokinetic profiles that affect the frequency of administration.

Gabapentin enacarbil extended release tablets available under the trade name Horizant (R):

The recommended dosage is 600 mg orally twice daily. Therapy should be initiated at a dose of 600 mg orally in the morning for 3 days of therapy, then increased to 600 mg twice daily (1,200 mg/day) on day four.

Gabapentin enacarbil extended release tablets available under the trade name Horizant (R) and gabapentin are not interchangeable.

Usual Adult Dose for Restless Legs Syndrome

Gabapentin enacarbil available under the trade name Horizant (R):
600 mg orally once daily with food at about 5 PM

Usual Pediatric Dose for Epilepsy

Less than 3 years: Effectiveness has not been established.

Greater than or equal to 3 and less than 12 years:
Starting Dose: ranges from 10 to 15 mg/kg/day in 3 divided doses.
Effective Dose: reached by upward titration over a period of approximately 3 days. The effective dose of gabapentin in patients 5 years of age and older is 25 to 35 mg/kg/day and given in divided doses (three times a day). The effective dose in pediatric patients ages 3 and 4 years is 40 mg/kg/day and given in divided doses (three times a day). Gabapentin may be administered as the oral solution, capsule, or tablet, or using combinations of these formulations. Dosages up to 50 mg/kg/day have been well tolerated in a long term clinical study. The maximum time interval between doses should not exceed 12 hours.

Greater than 12 years:
Initial dose: 300 mg orally on day one, 300 mg orally twice a day on day two, then 300 mg orally 3 times a day on day three.
Maintenance dose: 900 to 1800 mg orally in 3 divided doses. If necessary, the dose may be increased using 300 mg or 400 mg capsules three times a day up to 1800 mg/day. Dosages up to 2400 mg/day have been well tolerated in long term clinical studies. Doses of 3600 mg/day have also been administered to a small number of patients for a relatively short duration, and have been well tolerated. The maximum time between doses in the three times a day schedule should not exceed 12 hours.

Renal Dose Adjustments

For patients greater than or equal to 12 years:
CrCl less than 15 mL/min: 300 mg orally every other day
CrCl 15 to 30 mL/min: 300 mg orally once a day
CrCl 30 to 60 mL/min: 300 mg orally twice a day
CrCl greater than 60 mL/min: 400 mg orally 3 times a day

The dose of gabapentin available under the trade name Gralise (R) should be adjusted in patients with reduced renal function. Patients with reduced renal function should initiate Gralise (R) at a daily dose of 300 mg. Daily dosing in patients with reduced renal function should be individualized based on tolerability and desired clinical benefit. Gralise (R) should be titrated following the schedule outlined below:
CrCl less than 30 mL/min: Gralise (R) should not be administered
CrCl 30 to 60 mL/min: 600 to 1800 mg orally with the evening meal
CrCl greater than or equal to 60 mL/min: 1800 mg orally with the evening meal

The dose of gabapentin enacarbil available under the trade name Horizant (R) should be adjusted in patients with reduced renal function as follows:

Restless Legs Syndrome:
CrCl greater than or equal to 60 ml/min: 600 mg orally once a day
CrCl 30 to 59 ml/min: Start at 300 mg orally daily and increase to 600 mg as needed
CrCl 15 to 29 ml/min: 300 mg orally once a day
CrCl less than 15 ml/min: 300 mg orally every other day
CrCl less than 15 ml/min on dialysis: not recommended

Postherpetic Neuralgia:
CrCl greater than or equal to 60 ml/min: 600 mg orally in the morning for 3 days, then 600 mg twice a day thereafter.
CrCl 30 to 59 ml/min: 300 mg orally in the morning for 3 days, then 300 mg twice a day thereafter. Increase to 600 mg twice daily as needed based on tolerability and efficacy.
CrCl 15 to 29 ml/min: 300 mg orally in the morning on day 1 and day 3 of therapy, then 300 mg once a day in the morning. May increase to 300 mg twice daily if needed based on tolerability and efficacy.
CrCl less than 15 ml/min: 300 mg orally every other day in the morning. May increase to 300 mg once daily in the morning if needed based on tolerability and efficacy.
CrCl less than 15 ml/min on dialysis: 300 mg orally following every dialysis. May increase to 600 mg following every dialysis if needed based on efficacy and tolerability.

Liver Dose Adjustments

Data not available

Dose Adjustments

If the dose of gabapentin available under the trade name Gralise (R) is reduced, discontinued, or substituted with an alternative medication, this should be done gradually over a minimum of one week or longer or as directed by the physician.

If the dose of gabapentin enacarbil available under the trade name Horizant (R) is discontinued, patients with RLS receiving 600 mg or less once daily can discontinue the drug without tapering. Patients with PHN receiving Horizant (R) twice daily should reduce the dose to once daily for 1 week prior to discontinuation to minimize the potential for withdrawal seizure.

Precautions

If gabapentin is discontinued and/or an alternate anticonvulsant medication is added to the therapy, this should be done gradually over a minimum of 1 week.

The safety and effectiveness of gabapentin available under the trade names Gralise (R) or Horizant (R) in patients with epilepsy has not been studied.

Gabapentin available under the trade names Gralise (R) or Horizant (R) are not interchangeable with each other or with other gabapentin products.

Gabapentin available under the trade name Gralise (R) should be titrated to the maintenance dose.

Gabapentin available under the trade names Gralise (R) or Horizant (R) tablets should be swallowed whole, not crushed, split, or chewed.

If the dose of gabapentin available under the trade name Gralise (R) is reduced, discontinued, or substituted with an alternative medication, this should be done gradually over a minimum of one week or longer or as directed by the physician.

An antacid containing aluminum hydroxide and magnesium hydroxide reduced the bioavailability of gabapentin immediate release by about approximately 20%, but by only 5% when gabapentin was taken 2 hours after antacids. It is recommended that gabapentin available under the trade name Gralise (R) be taken at least 2 hours following antacid administration.

Safety and effectiveness of gabapentin available under the trade names Gralise (R) or Horizant (R) have not been established in pediatric patients (less than 18 years of age).

Dialysis

A 200 to 300 mg dose should be administered following dialysis.

Gabapentin available under the trade name Gralise (R) is contraindicated in patients receiving dialysis.

Gabapentin enacarbil available under the trade name Horizant (R):
RLS:
CrCl less than 15 ml/min on dialysis: Not recommended
PHN:
CrCl less than 15 ml/min on dialysis: 300 mg orally following every dialysis. May increase to 600 mg following every dialysis if needed based on tolerability and efficacy.

Other Comments

Gabapentin may be given with or without food. Gabapentin enacarbil available under the trade name Horizant (R) should be taken with food.

Gabapentin available under the trade name Gralise (R) should be taken once daily with the evening meal.

Gabapentin enacarbil available under the trade name Horizant (R) should be swallowed whole and should not be cut, crushed, or chewed. For RLS, a daily dose of 1,200 mg provided no additional benefit compared with the 600 mg dose, but caused an increase in adverse reactions. For PHN, a daily dose greater than 1,200 mg conferred no additional benefit and resulted in an increase in adverse reactions.

If the dose of Horizant (R) is not taken at the recommended time, it should be skipped, and the next dose should be taken at the time of the next scheduled dose.

What are the side effects of gabapentin?

Gabapentin Side Effects

Common side effects of gabapentin include:

Sleepiness
Dizziness
Fatigue
Clumsiness while walking
Visual changes, including double vision
Tremor
Runny nose
Weight gain
Indigestion or nausea
Nervousness
Muscle ache
Dry mouth or sore throat
Memory loss
Headache
Unusual thoughts
Diarrhea or constipation
Swelling of hands or feet
Fever
Itchy eyes

Serious side effects can also occur. If you have any of these side effects, call your doctor right away:

Thoughts of suicide or harming yourself
Fever or swelling of lymph nodes
Severe rash
Swelling of the face, lips, or tongue
Difficulty breathing or swallowing
Seizure

What are the precautions of gabapentin?

Capsules: 100, 300, and 400 mg.
Tablets: 100, 300, 400, 600, and 800 mg.
Solution: 250 mg/5 ml