Last reviewed by Miljan Krcobic on August 28th, 2018.
What is Gabapentin? What is Gabapentin used for?
Gabapentin is a Generic name for a drug that is used as an anti-epileptic or anticonvulsant. This drug exhibits it actions by affecting chemicals in the brain and nerves in the body that may be the cause of seizures and some types of pain. It is most commonly prescribed in the treatment of epilepsy in patients older than 12, and partial seizures in children ages 3 to 12.
It also prescribed in adults to treat nerve pain caused by herpes zoster virus or shingles. Gabapentin may also be prescribed to treat restless legs syndrome (RLS), to prevent hot flashes and to relieve numbness and tingling related to diabetes.
It is off-label prescribed for the long-term treatment of migraine. A study from 2013 published in the Canadian Journal of Anesthesia revealed that gabapentin is efficient in relieving moderate to high levels of anxiety among people about to have surgery.
The researchers noted that doctors are increasingly using the drug to treat pain after surgery as well as a variety of psychiatric diseases, such as chronic anxiety disorders. Gabapentin comes in following forms that are taken by mouth: an immediate-release tablet, an extended-release tablet, a capsule, and a solution. It is most commonly used in doses of: 100 mg, 300 mg, 400 mg, 600 mg and 800 mg.
This drug is usually well tolerated in most patients, has a fairly mild side-effect profile, and passes unmetabolized through the body. It is also available as the brand-name drugs named Horizant, Gralise and Neurontin. FDA approved gabapentin in 1993 under the brand name Neurontin originally manufacturer by Pfizer.
What is Xanax? What is Xanax used for?
Xanax is a Brand name for a medicine containing short-acting benzodiazepine drug named alprazolam as an active ingredient. This drug works by affecting chemicals in the brain that are known as neurotransmitters and may be unbalanced in patients with different types of anxiety disorders. Xanax indications are: panic disorders with or without agoraphobia, generalized anxiety disorder and anxiety linked with depression.
It is available in the form of immediate release tablet in doses of: 0.25, 1, 2 and 5 mg and in form of extended release tablet, named as Xanax XR in doses of 3 and 5 mg. Xanax is manufactured by Pfizer. FDA approved alprazolam in 1981. Xanax is also available as a generic drug.
What is the difference between Gabapentin and Xanax in their mechanism of action?
Gabapentin works by interacting with cortical neurons at auxillary subunits of voltage-sensitive calcium channels. Gabapentin increases the amounts of GABA in synaptic spaces, enhances responses to GABA at non-synaptic sites in neuronal tissues, and decreases mono-amine neurotransmitters release.
It mostly acts in the CA1 area of the hippocampus mediated through its binding to presynaptic NMDA receptors. Studies also showed that antiallodynic and the antihyperalgesic gabapentin effects are mediated by the descending noradrenergic system, and the activation of spinal alpha2-adrenergic receptors. This substance can also bind and activate the adenosine A1 receptor.
Alprazolam, which is the active ingredient of Xanax, is a benzodiazepine structured molecule that works by binding to benzodiazepine BNZ-1 and BNZ-2 receptors, which are responsible for sleep induction, anticonvulsant activity, memory functions and motor coordination. Those receptors are coupled with GABAA receptors. By binding to them alprazolam increases GABA neurotransmitter inhibitory effects in the brain.
Differences and similarities between Gabapentin and Xanax
Gabapentin and alprazolam from Xanax are in general different drugs. However there are some similarities in their indication profile and in mechanism of action by which these drugs can be comparable.
From chemistry standpoint these two drugs are different. Gabapentin belongs to the class of organic compounds that are known as gamma amino acids and derivatives which are actually amino acids having amino group coupled with gamma carbon atom. Alprazolam belongs to the class of organic compounds known as 1,4-benzodiazepines, organic compounds with benzene ring fused to a 1,4-azepine.
Beside their chemical structural difference, their mechanism of action is quite similar. Both drugs works by affecting the major inhibitory neurotransmitter in the brain named GABA, by increasing response and effects of this transmitter in neuronal synapses and tissue. Differently from alprazolam, gabapentin may also exhibit its action by binding to adrenergic, NMDA and adenosine receptors in the brain.
From the pharmacokinetic standpoint there are both differences and similarities. Both drugs are rapidly absorbed after oral administration. Alprazolam bioavailability is 80-90 %. Gabapentin absorption is in part dependent by the L-amino acid transport saturable system which means when dose increases, bioavailability decreases.
Bioavailability of gabapentin ranges from approximately 60% after use of 900 mg dose daily to approximately 27% for a 4800 mg dose per day. Food may also have an effect on the absorption rate with about 14% increase. Alprazolam binds to plasma proteins in 80 % range, mainly to albumin compared to less than 3% of plasma protein-bind gabapentin.
Alprazolam is metabolized in the liver via hydroxylation to α-hydroxyalprazolam, which is also active compound in the body. Metabolites are later excreted in urine as glucuronides. Gabapentin remains unmetabolized in the body, and it is excreted in the urine in original form. Half-life elimination time of gabapentin is 5-7 hours in healthy individuals.
This means that approximately 50% of administrated gabapentin will be cleared from your body within 5 to 7 hours on average. Using this information, it can be determined that gabapentin will be eliminated from the system within 1.15 to 1.60 days after your final dose. In other words, you shouldn’t expect any of the gabapentin to remain in systemic circulation after 2 days of ingestion. The elimination half-life time of Xanax ranges from 9-16 hours. This means that it will take about 9 to 16 hours of ingestion to eliminate 50% of the drug from the body. Most people will fully eliminated (100%) Xanax from their system within 4 days.
There are no labels indication in which those drugs can be comparable. Xanax belong to the class of benzodiazepines, drugs that are used in the treatment of seizures (for example clonazepam – Klonopin and lorazepam) however studies and results showed that Xanax is not as good as clonazepam or lorazepam in relaxing muscle spasms.
However, gabapentin is used off-label for the treatment of anxiety disorders in comparison with Xanax which is approved for this indication. There are many studies of gabapentin for anxiety disorders use due to its unique GABA-ergic mechanism of action. Nearly every published study has been found that Gabapentin is superior in reduction of anxiety compared to a placebo.
A randomized, placebo-controlled, double-blind study from 1999 revealed gabapentin’s safety and efficacy among individuals diagnosed with social anxiety disorder. It has been noted that social anxiety levels were reduced among patients taking gabapentin compared to the placebo. However, side effects including dizziness, dry mouth, and nausea were more prevalent among patients receiving gabapentin compared to the placebo.
But, there are notable disadvantages associated with using gabapentin for the treatment of anxiety. The most obvious disadvantage is that there aren’t enough large and targeted studies to suggest gabapentin is an effective anxiolytic.
The main reason for that is that, most studies were implemented only on adults, there were no long-term studies, efficacy is questionable and gabapentin is used off-label and is no FDA approved for anxiety disorder treatment.
Gabapentin and Xanax side effects
|Gabapentin possible side effects||Xanax possible side effects|
|Ataxia (1-13%)||Drowsiness (41%)|
|Dizziness (16-20%)||Depression (10-15%)|
|Drowsiness (5-21%)||Headache (10-15%)|
|Fatigue (11-15%)||Constipation (10-15%)|
|Somnolence (16-20%)||Diarrhea (10-15%)|
|Diplopia (6-10%)||Dry mouth (10-15%)|
|Nystagmus (6-10%)||Tachycardia (5-10%)|
|Tremor (6-10%)||Confusion (5-10%)|
|Amblyopia (1-5%)||Insomnia (5-10%)|
|Back pain (1-5%)||Nausea/vomiting (5-10%)|
|Constipation (1-5%)||Blurred vision (5-10%)|
|Depression (1-5%)||Nasal congestion (5-10%)|
|Dry mouth (1-5%)||Hypotension (1-5%)|
|Dysarthria (1-5%)||Syncope (1-5%)|
|Dyspepsia (1-5%)||Akathisia (1-5%)|
|Hostility (5-8% children)||Dizziness (1-5%)|
|Hyperkinesia (3-5%)||Increased salivation (1-5%)|
|Increased appetite (1-5%)||Nervousness (1-5%)|
|Leukopenia (1-5%)||Tremor (1-5%)|
|Myalgia (1-5%)||Weight change (1-5%)|
|Peripheral edema (1-5%)|
|Weight gain (1-5%)|
|Abnormal vision (>1%)|
Postmarketing Reports after Xanax use:
× Gastrointestinal side effects: hepatitis, liver enzyme elevations, hepatic failure
× CNS side effects: Hypomania, mania
× Immunologic side effects: Stevens-Johnson syndrome, peripheral edema, angioedema,
× Endocrine side effects: Hyperprolactinemia, gynecomastia, galactorrhea
Which one is expensive, Gabapentin or Xanax?
According to drugs.com:
× The cost for Gabapentin capsule 100 mg is around $18 for a supply of 90 capsules
× The cost for Gabapentin capsule 300 mg is around $19 for a supply of 90 capsules
× The cost for Gabapentin capsule 400 mg is around $20 for a supply of 90 capsules
× The cost for Gabapentin tablet 600 mg is around $28 for a supply of 90 tablets
× The cost for Gabapentin tablet 800 mg is around $18 for a supply of 90 tablets
× The cost for Xanax tablet 0.25 mg is around $323 for a supply of 100 tablets
× The cost for Xanax tablet 0. 5 mg is around $400 for a supply of 100 tablets
× The cost for Xanax tablet 1 mg is around $533 for a supply of 100 tablets
× The cost for Xanax tablet 2 mg is around $902 for a supply of 100 tablets
Prices depend on the pharmacy you visit. Prices are for cash paying customers only and are not valid with insurance plans.
Warnings and precautions during Xanax and Gabapentin use
× Patients should not take Xanax if theyu are allergic to alprazolam, or any of the inactive ingredients of this medicine, or if they are allergic to other benzodiazepines, such as Librium, Valium, Tranxene, Ativan, or Serax and others.
× Never take Xanax if you have narrow-angle glaucoma.
× Xanax should not be used if you are taking the antifungal medicines Spornaox or Nizoral
× Xanax causes drowsiness and decrease your ability to drive safely or operate machinery. If you take Xanax with other drugs that cause drowsiness, or if you are elderly or debilitated, you may become particularly sleepy and unable to function during the day.
× Xanax is addictive substance, so do not take higher doses for a longer time than your doctor recommends. You can also become tolerant, and drug may be less effective.
× Before taking Xanax, consult your doctor if you have: depression, Suicidal thoughts, breathing problems, history of alcoholism or drug abuse, personality disorder, liver or kidney problems.
× You should also tell your doctor what other prescription and nonprescription medications, nutritional supplements and vitamins you take, because some of them may interact with Xanax. Also, tell your doctor if you smoke.
× Never increase the dose without talking to your doctor first, even if you think the Xanax doesn’t work anymore.
× Gabapentin may increase the risk for suicide. Suicidal behavior and thoughts occurs in about one in 500 people in patients who are taking similar drugs to gabapentin. This risk may begin within a week of starting treatment.
× You should let your doctor know if you experience: suicidal thoughts, symptoms of depression, aggression, irritability, panic attacks, extreme worry, restlessness, acting without thinking, judgment impairment, and abnormal excitement. You should also let family and friends to know about these symptoms. If such symptoms, or if a friend or family member thinks you are acting strange, call your doctor right away.
× Children at ages of 3 to 12 may experience changes in behavior while taking gabapentin, including: restlessness, poor performance at school, inability to pay attention and angry or aggressive behavior. Children who are younger than 3 years should not take gabapentin for seizures treatment. Children should also not take gabapentin to treat postherpetic neuralgia.
× Gabapentin has to be used with caution in elderly patients with kidney disease
× Alcohol may interact with gabapentin making side effects more severe and frequent
× Never stop gabapentin therapy suddenly because you could experience withdrawal symptoms including sleep disturbance, anxiety, nausea, pain, and sweating.
× Dose of gabapentin should be reduced gradually over a period of at least one week and only with your doctor monitoring and advice.
× You should tell your doctor if you are taking any prescription pain medications called opioids also known as narcotics. These medicines may increase drowsiness or dizziness if they are taken together with gabapentin.
× If you have some kidney disease or you should have any surgery planned including dental or if you have ever had a problem with drug or alcohol abuse let your doctor know before staring therapy with gabapentin.
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