Gabapentin 300mg Capsules
It is used to treat painful nerve diseases.It is used to help control certain kinds of seizures.It may be given to you for other reasons. Talk with the doctor.
Drug Class
Anticonvulsant; Neuropathic Pain Agent
Pharmacologic Class
GABA Analog
Pregnancy Category
Not available
FDA Approved
Dec 1993
DEA Schedule
Not Controlled
Overview
What is this medicine?
Gabapentin is a medication used to treat certain types of seizures (epilepsy) and nerve pain, such as the pain that can occur after shingles (postherpetic neuralgia). It works by affecting certain chemicals and electrical signals in the brain and nervous system.
How to Use This Medicine
Taking Your Medication
To use this medication correctly, follow your doctor's instructions and read all the information provided. Continue taking the medication as directed by your doctor or healthcare provider, even if you start to feel better. If you are taking an antacid containing aluminum or magnesium, wait at least 2 hours after taking the antacid before taking this medication. You can take this medication with or without food. Swallow the tablet whole with a full glass of water.
Storing and Disposing of Your Medication
Store this medication at room temperature in a dry place, avoiding the bathroom. Keep all medications in a safe location, out of the reach of children and pets. Dispose of unused or expired medications properly. Do not flush them down the toilet or pour them down the drain unless instructed to do so. If you have questions about disposing of your medication, consult your pharmacist. You may also want to check if there are drug take-back programs in your area.
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it is close to the time for your next dose, skip the missed dose and resume your regular schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
To use this medication correctly, follow your doctor's instructions and read all the information provided. Continue taking the medication as directed by your doctor or healthcare provider, even if you start to feel better. If you are taking an antacid containing aluminum or magnesium, wait at least 2 hours after taking the antacid before taking this medication. You can take this medication with or without food. Swallow the tablet whole with a full glass of water.
Storing and Disposing of Your Medication
Store this medication at room temperature in a dry place, avoiding the bathroom. Keep all medications in a safe location, out of the reach of children and pets. Dispose of unused or expired medications properly. Do not flush them down the toilet or pour them down the drain unless instructed to do so. If you have questions about disposing of your medication, consult your pharmacist. You may also want to check if there are drug take-back programs in your area.
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it is close to the time for your next dose, skip the missed dose and resume your regular schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
Lifestyle & Tips
- Do not stop taking gabapentin suddenly, as this can lead to withdrawal symptoms or increased seizure activity. Your doctor will guide you on how to slowly reduce the dose if needed.
- Avoid alcohol and other medications that cause drowsiness (like opioids, sedatives, or tranquilizers) while taking gabapentin, as this can increase dizziness, drowsiness, and the risk of serious breathing problems.
- Gabapentin may cause dizziness, drowsiness, or problems with coordination. Be careful when driving or operating machinery until you know how this medication affects you.
- Report any new or worsening mood changes, depression, anxiety, or thoughts of self-harm to your doctor immediately.
- Take gabapentin with or without food, but consistently. If taking antacids, take gabapentin at least 2 hours after the antacid.
Available Forms & Alternatives
Available Strengths:
- Gabapentin 600mg Tablets
- Gabapentin 800mg Tablets
- Gabapentin 400mg Capsules
- Gabapentin 100mg Capsules
- Gabapentin 300mg Capsules
- Gabapentin 300mg Capsules
- Gabapentin 250mg/5ml Sol No Xylitol
- Gabapentin 250mg/5ml Solution
- Gabapentin 600mg Tablet(once Daily)
- Gabapentin 300mg Tablet(once Daily)
- Gabapentin 600mg Tablet(once Daily)
- Gabapentin 300mg Tablet(once Daily)
Dosing & Administration
Adult Dosing
Standard Dose:
Initial: 300 mg on Day 1, 300 mg BID on Day 2, 300 mg TID on Day 3. Titrate to effect. Maintenance: 900-1800 mg/day in 3 divided doses for neuropathic pain; 900-3600 mg/day in 3 divided doses for epilepsy.
Dose Range:
900 - 3600 mg
Condition-Specific Dosing:
Postherpetic Neuralgia:
Initial: 300 mg on Day 1, 300 mg BID on Day 2, 300 mg TID on Day 3. Titrate to 1800 mg/day. Max: 1800 mg/day.
Epilepsy (Adjunctive Therapy):
Initial: 300 mg on Day 1, 300 mg BID on Day 2, 300 mg TID on Day 3. Titrate to 900-1800 mg/day. Max: 3600 mg/day.
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Epilepsy (3-12 years): Initial 10-15 mg/kg/day in 3 divided doses. Titrate over 3 days to target 25-35 mg/kg/day in 3 divided doses. Max: 50 mg/kg/day.
Adolescent:
Epilepsy (>=12 years): Same as adult initial titration, then 900-3600 mg/day in 3 divided doses.
Dose Adjustments
Renal Impairment:
Mild:
CrCl >60 mL/min: 900-3600 mg/day in 3 divided doses.
Moderate:
CrCl 30-59 mL/min: 400-1400 mg/day in 2 divided doses.
Severe:
CrCl 15-29 mL/min: 200-700 mg/day in 1-2 divided doses. CrCl <15 mL/min: 100-300 mg/day in 1 divided dose.
Dialysis:
Loading dose of 300-400 mg, then 200-300 mg after each 4-hour hemodialysis session.
Confidence:
High
Hepatic Impairment:
Mild:
No adjustment needed.
Moderate:
No adjustment needed.
Severe:
No adjustment needed.
Confidence:
High
Pharmacology
Mechanism of Action
Gabapentin is structurally related to the neurotransmitter GABA but does not bind to GABA-A or GABA-B receptors, nor does it inhibit GABA uptake or degradation. Its precise mechanism of action is unknown, but it is thought to exert its effects by binding with high affinity to the alpha-2-delta (ι2δ) subunit of voltage-gated calcium channels in the central nervous system. This binding is believed to reduce the release of excitatory neurotransmitters, thereby modulating neuronal excitability and pain signaling.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 60% at 300 mg, decreasing to ~35% at 1600 mg (dose-dependent)
Tmax:
2-3 hours
FoodEffect:
Food slightly increases Tmax but has no significant effect on the extent of absorption.
Distribution:
Vd:
57.7 L
ProteinBinding:
<3%
CnssPenetration:
Yes
Elimination:
HalfLife:
5-7 hours
Clearance:
Eliminated from systemic circulation by renal excretion as unchanged drug.
ExcretionRoute:
Renal
Unchanged:
>90%
Pharmacodynamics
OnsetOfAction:
Days to weeks (for full therapeutic effect)
PeakEffect:
Not precisely defined for chronic use; peak plasma concentrations 2-3 hours post-dose.
DurationOfAction:
Approximately 8 hours (due to TID dosing requirement)
Confidence:
Medium
Safety & Warnings
BLACK BOX WARNING
Serious breathing problems (respiratory depression) may occur when gabapentin is taken with opioid pain medicines or other medicines that can cause drowsiness, or in people who have underlying lung problems. Patients should be monitored for respiratory depression and sedation. The risk of suicidal thoughts or behavior (suicidality) is also increased with antiepileptic drugs (AEDs), including gabapentin.
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you or your caregiver notice any of the following symptoms, contact your doctor or seek medical attention immediately:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Neurological problems, such as:
+ Trouble controlling body movements
+ Twitching
+ Change in balance
+ Trouble swallowing or speaking
Cognitive issues, including:
+ Memory problems or loss
+ Change in eyesight
+ Inability to control eye movements
Confusion, difficulty focusing, or changes in behavior
Shakiness
Respiratory problems, such as:
+ Trouble breathing
+ Slow breathing
+ Shallow breathing
Blue or gray discoloration of the skin, lips, nail beds, fingers, or toes
Swelling in the arms or legs
Severe dizziness or fainting
Excessive sleepiness, dizziness, or fainting
If you or your caregiver notice any of the following, seek medical help right away:
Unresponsiveness
Unusual behavior or lack of reaction
Failure to wake up
Like other seizure medications, this drug may increase the risk of suicidal thoughts or actions, particularly in individuals with a history of suicidal ideation. If you experience any new or worsening symptoms, such as:
Depression
Anxiety
Restlessness
Irritability
Panic attacks
Mood or behavioral changes
contact your doctor immediately. If you have suicidal thoughts or actions, seek help right away.
Severe Skin Reactions
This medication may cause severe skin reactions, which can be life-threatening and affect internal organs. Seek medical help immediately if you experience:
Red, swollen, blistered, or peeling skin
Red or irritated eyes
Sores in the mouth, throat, nose, eyes, genitals, or skin
Fever, chills, or sore throat
Body aches
Shortness of breath
Muscle pain or weakness
Unexplained bruising or bleeding
Fatigue or weakness
Dark urine or yellow skin and eyes
Difficulty urinating
Swollen glands
Other Side Effects
Most people experience no side effects or only mild side effects while taking this medication. However, if you experience any of the following, contact your doctor or seek medical attention:
Dizziness
Drowsiness
Fatigue
Weakness
Diarrhea
Upset stomach
Nausea or vomiting
* Dry mouth
These are not all the possible side effects of this medication. If you have questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you or your caregiver notice any of the following symptoms, contact your doctor or seek medical attention immediately:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Neurological problems, such as:
+ Trouble controlling body movements
+ Twitching
+ Change in balance
+ Trouble swallowing or speaking
Cognitive issues, including:
+ Memory problems or loss
+ Change in eyesight
+ Inability to control eye movements
Confusion, difficulty focusing, or changes in behavior
Shakiness
Respiratory problems, such as:
+ Trouble breathing
+ Slow breathing
+ Shallow breathing
Blue or gray discoloration of the skin, lips, nail beds, fingers, or toes
Swelling in the arms or legs
Severe dizziness or fainting
Excessive sleepiness, dizziness, or fainting
If you or your caregiver notice any of the following, seek medical help right away:
Unresponsiveness
Unusual behavior or lack of reaction
Failure to wake up
Like other seizure medications, this drug may increase the risk of suicidal thoughts or actions, particularly in individuals with a history of suicidal ideation. If you experience any new or worsening symptoms, such as:
Depression
Anxiety
Restlessness
Irritability
Panic attacks
Mood or behavioral changes
contact your doctor immediately. If you have suicidal thoughts or actions, seek help right away.
Severe Skin Reactions
This medication may cause severe skin reactions, which can be life-threatening and affect internal organs. Seek medical help immediately if you experience:
Red, swollen, blistered, or peeling skin
Red or irritated eyes
Sores in the mouth, throat, nose, eyes, genitals, or skin
Fever, chills, or sore throat
Body aches
Shortness of breath
Muscle pain or weakness
Unexplained bruising or bleeding
Fatigue or weakness
Dark urine or yellow skin and eyes
Difficulty urinating
Swollen glands
Other Side Effects
Most people experience no side effects or only mild side effects while taking this medication. However, if you experience any of the following, contact your doctor or seek medical attention:
Dizziness
Drowsiness
Fatigue
Weakness
Diarrhea
Upset stomach
Nausea or vomiting
* Dry mouth
These are not all the possible side effects of this medication. If you have questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Signs of an allergic reaction (hives, difficulty breathing, swelling of your face, lips, tongue, or throat)
- Severe skin rash (e.g., Stevens-Johnson syndrome)
- Swollen glands, fever, muscle aches, severe weakness, unusual bruising or bleeding
- Increased seizures or new types of seizures
- Extreme drowsiness or sedation
- Slow or shallow breathing
- Unusual changes in mood or behavior (e.g., agitation, hostility, depression, suicidal thoughts)
- New or worsening swelling in your hands or feet
- Unexplained muscle pain, tenderness, or weakness (especially if accompanied by fever or dark urine)
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced.
If you have kidney disease or are undergoing dialysis.
This list is not exhaustive, and it is crucial to discuss all your medications (including prescription, over-the-counter, natural products, and vitamins) and health conditions with your doctor and pharmacist. They will help determine if it is safe to take this medication with your other medications and health issues.
Remember, do not start, stop, or adjust the dosage of any medication without first consulting your doctor.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced.
If you have kidney disease or are undergoing dialysis.
This list is not exhaustive, and it is crucial to discuss all your medications (including prescription, over-the-counter, natural products, and vitamins) and health conditions with your doctor and pharmacist. They will help determine if it is safe to take this medication with your other medications and health issues.
Remember, do not start, stop, or adjust the dosage of any medication without first consulting your doctor.
Precautions & Cautions
Important Warnings and Cautions
When taking this medication, it is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are using this drug.
To ensure your safety, avoid driving and engaging in activities that require alertness until you understand how this medication affects you.
This medication may interfere with certain laboratory tests. Be sure to notify all your healthcare providers and laboratory personnel that you are taking this drug. Additionally, follow your doctor's instructions for regular blood work and other laboratory tests.
Before consuming alcohol, marijuana, or other forms of cannabis, or taking prescription or over-the-counter medications that may cause drowsiness, consult with your doctor.
Note that this medication is not interchangeable with gabapentin enacarbil (Horizant). Do not substitute one for the other without consulting your doctor.
To minimize the risk of side effects, do not suddenly stop taking this medication without consulting your doctor. If you need to discontinue use, your doctor will provide guidance on gradually tapering off the medication. Severe respiratory problems have occurred in individuals taking this medication, particularly when combined with opioid pain medications or in those with pre-existing lung or breathing issues. This risk is higher in people over 65 years old, and in some cases, has been fatal. If you have concerns, discuss them with your doctor.
If you are 65 years or older, use this medication with caution, as you may be more susceptible to side effects.
For children between 3 and 12 years old, use this medication with caution, as they may be at a higher risk of developing mood or behavioral problems.
If you are pregnant, plan to become pregnant, or are breastfeeding, consult with your doctor to discuss the potential benefits and risks to you and your baby.
Specific Considerations for Seizure Treatment
If you experience changes in your seizure patterns or worsening seizures after starting this medication, consult with your doctor.
When taking this medication, it is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are using this drug.
To ensure your safety, avoid driving and engaging in activities that require alertness until you understand how this medication affects you.
This medication may interfere with certain laboratory tests. Be sure to notify all your healthcare providers and laboratory personnel that you are taking this drug. Additionally, follow your doctor's instructions for regular blood work and other laboratory tests.
Before consuming alcohol, marijuana, or other forms of cannabis, or taking prescription or over-the-counter medications that may cause drowsiness, consult with your doctor.
Note that this medication is not interchangeable with gabapentin enacarbil (Horizant). Do not substitute one for the other without consulting your doctor.
To minimize the risk of side effects, do not suddenly stop taking this medication without consulting your doctor. If you need to discontinue use, your doctor will provide guidance on gradually tapering off the medication. Severe respiratory problems have occurred in individuals taking this medication, particularly when combined with opioid pain medications or in those with pre-existing lung or breathing issues. This risk is higher in people over 65 years old, and in some cases, has been fatal. If you have concerns, discuss them with your doctor.
If you are 65 years or older, use this medication with caution, as you may be more susceptible to side effects.
For children between 3 and 12 years old, use this medication with caution, as they may be at a higher risk of developing mood or behavioral problems.
If you are pregnant, plan to become pregnant, or are breastfeeding, consult with your doctor to discuss the potential benefits and risks to you and your baby.
Specific Considerations for Seizure Treatment
If you experience changes in your seizure patterns or worsening seizures after starting this medication, consult with your doctor.
Overdose Information
Overdose Symptoms:
- Double vision
- Slurred speech
- Drowsiness
- Lethargy
- Diarrhea
- Sedation
- Coma (in severe cases, especially with co-ingestion of other CNS depressants)
What to Do:
Seek immediate medical attention. Call 911 or Poison Control at 1-800-222-1222. There is no specific antidote; treatment is supportive.
Drug Interactions
Major Interactions
- Opioids (e.g., morphine, hydrocodone, oxycodone): Increased risk of respiratory depression, profound sedation, coma, and death.
- Other CNS depressants (e.g., benzodiazepines, alcohol, sedatives/hypnotics, tricyclic antidepressants): Additive CNS depression.
Moderate Interactions
- Antacids (containing aluminum and magnesium): May decrease gabapentin bioavailability. Administer gabapentin at least 2 hours after antacid administration.
- Naproxen: May increase gabapentin exposure (AUC).
Monitoring
Baseline Monitoring
Renal function (Creatinine Clearance)
Rationale: Gabapentin is primarily renally excreted; dose adjustment is necessary in renal impairment.
Timing: Prior to initiation of therapy.
Routine Monitoring
Clinical response (seizure frequency, pain intensity)
Frequency: Regularly during titration and maintenance.
Target: Reduction in symptoms without intolerable side effects.
Action Threshold: Lack of efficacy or significant adverse effects warrant dose adjustment or discontinuation.
Adverse effects (dizziness, somnolence, ataxia, peripheral edema, weight gain)
Frequency: Regularly, especially during titration.
Target: Absence or tolerability of side effects.
Action Threshold: Intolerable side effects may require dose reduction or discontinuation.
Mood and behavior changes (e.g., suicidal ideation, depression, aggression)
Frequency: Regularly, especially during initial therapy and dose changes.
Target: Stable mood and behavior.
Action Threshold: Emergence or worsening of suicidal thoughts/behavior or unusual changes in mood/behavior.
Respiratory status (if co-administered with opioids or other CNS depressants, or in patients with respiratory risk factors)
Frequency: Closely monitor, especially at initiation or dose increase.
Target: Normal respiratory rate and effort.
Action Threshold: Signs of respiratory depression (e.g., shallow breathing, cyanosis).
Symptom Monitoring
- Dizziness
- Somnolence
- Ataxia
- Fatigue
- Peripheral edema
- Weight gain
- Blurred vision
- Tremor
- Nausea
- Vomiting
- Suicidal thoughts or behavior
- Depression
- Anxiety
- Agitation
- Hostility
- Restlessness
- Hyperactivity
- Unusual changes in mood or behavior
- Difficulty breathing (especially with opioids)
Special Patient Groups
Pregnancy
Gabapentin is not recommended during pregnancy unless the potential benefits outweigh the potential risks to the fetus. Animal studies have shown developmental toxicity. There is a pregnancy exposure registry for women taking antiepileptic drugs.
Trimester-Specific Risks:
First Trimester:
Limited human data, but animal studies suggest potential for skeletal and visceral abnormalities. Risk of major congenital malformations with AEDs is generally higher than in the general population.
Second Trimester:
Not specifically studied, but continued exposure may carry risks.
Third Trimester:
Not specifically studied. Neonatal withdrawal symptoms have been reported in infants exposed to gabapentin in utero.
Lactation
Gabapentin is excreted into breast milk. While generally considered compatible with breastfeeding (L3), monitor breastfed infants for sedation, poor feeding, and weight gain. Consult with a healthcare provider.
Infant Risk:
Low to moderate risk. Monitor for drowsiness, lethargy, poor feeding, or developmental delays.
Pediatric Use
Safety and efficacy for epilepsy established in children 3-12 years. Not recommended for neuropathic pain in children. Behavioral problems (e.g., aggression, hyperactivity) have been reported more frequently in pediatric patients.
Geriatric Use
Elderly patients may be more sensitive to the side effects of gabapentin (e.g., dizziness, somnolence, ataxia). Dose adjustments are often necessary based on renal function, which commonly declines with age.
Clinical Information
Clinical Pearls
- Gabapentin requires careful titration (gradual dose increase) to minimize side effects like dizziness and somnolence.
- It is not effective for acute pain and is primarily used for neuropathic pain.
- Despite its name, gabapentin does not directly act on GABA receptors but rather on voltage-gated calcium channels.
- Bioavailability is saturable and dose-dependent, meaning a higher dose does not proportionally increase absorption.
- Always check renal function before initiating and periodically during therapy, as gabapentin is exclusively renally cleared.
- Patients should be advised not to abruptly discontinue gabapentin due to potential for withdrawal symptoms or increased seizure frequency.
- Commonly used off-label for restless legs syndrome, anxiety disorders, and alcohol withdrawal.
Alternative Therapies
- Pregabalin (for neuropathic pain, epilepsy)
- Carbamazepine (for neuropathic pain, epilepsy)
- Oxcarbazepine (for epilepsy)
- Lamotrigine (for epilepsy)
- Topiramate (for epilepsy)
- Duloxetine (for neuropathic pain)
- Venlafaxine (for neuropathic pain)
- Tricyclic antidepressants (e.g., amitriptyline, nortriptyline for neuropathic pain)
Cost & Coverage
Average Cost:
$10 - $50 per 30 capsules (300mg generic)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (for generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it's essential to contact your doctor promptly. To ensure your safety, never share your medication with others or take someone else's medication. This medication is accompanied by a Medication Guide, which provides crucial information. Please read this guide carefully and review it again whenever you receive a refill. If you have any questions or concerns about this medication, don't hesitate to discuss them with your doctor, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. Be prepared to provide detailed information about the overdose, including the medication taken, the amount, and the time it occurred.