|Summary sheet: Gabapentin|
|Common names||Gabapentin, Neurontin, Gabarone, Gralise|
|Systematic name||1-(Aminomethyl)cyclohexaneacetic acid|
|Routes of Administration|
Gabapentin (also known as Neurontin) is a depressant substance of the gabapentinoid class which is used as an anticonvulsant, analgesic and anxiolytic. It was originally developed to treat epilepsy and is currently used to relieve neuropathic pain and restless leg syndrome. It is recommended as a first line agent for the treatment of neuropathic pain arising from diabetic neuropathy, post-herpetic neuralgia, and central neuropathic pain.
Gabapentin is also an effective tool for treating social anxiety disorder, panic disorder and generalized anxiety disorder. It is these effects which provide gabapentin with some recreational potential in a manner that can be accurately compared to a mild benzodiazepine. However, these recreational effects diminish with repeated usage and are most commonly reported by those who try this compound who do not have a tolerance.
The bioavailability of gabapentin is relatively low and is inversely proportional to the dose. This means that higher doses have lower biovailability than lower doses. The bioavailability of gabapentin is approximately 60%, 47%, 34%, 33%, and 27% following 900, 1200, 2400, 3600, and 4800 mg/day Eating a high fat meal substantially increases gabapentin's bioavailability.
- 1 Chemistry
- 2 Pharmacology
- 3 Subjective effects
- 4 Toxicity and harm potential
- 5 Legal status
- 6 See also
- 7 External links
- 8 References
Gabapentin, or 1-(aminomethyl)cyclohexanacetic acid, is an analogue of the neurotransmitter GABA. It contains a cyclohexane ring bound to a methylamino chain CH3NH2. At the same location, R1, the cyclohexane ring is also substituted with an acetic acid group. Gabapentin is structurally analagous to GABA. GABA contains an amino group bound to the terminal carbon of a butanoic acid chain. The structure of gabapentin contains the secondary carbon R3 of the butanoic acid chain in GABA incorporated into an attached cyclohexane ring, converting it into a tertiary carbon while still maintaining the chain.
Gabapentin modulates the action of glutamate decarboxylase (GAD) and branched chain aminotransferase (BCAT), two enzymes involved in GABA biosynthesis. In human and rat studies, gabapentin was found to increase GABA biosynthesis, and to increase non-synaptic GABA neurotransmission in vitro. As the GABA system is the most prolific inhibitory receptor set within the brain, its modulation results in the sedating (or calming effects) of gabapentin on the nervous system.
Gabapentin has also been shown to bind to the α2δ-1 subunit of voltage-gated calcium ion channels which contributes to its analgesic effects. It is uncertain how this contributes to gabapentin's psychoactive effects.
The effects listed below are based upon the subjective effects index and personal experiences of PsychonautWiki contributors. The listed effects should be taken with a grain of salt and will rarely (if ever) occur all at once, but heavier doses will increase the chances and are more likely to induce a full range of effects. Likewise, adverse effects become much more likely on higher doses and may include serious injury or death.
- Sedation - Gabapentin is mildly sedating and can produce a lethargic state. At higher doses it may lead to a moderate sedated state.
- Muscle relaxation - While this effect is generally less powerful than that of benzodiazepines, it is still prevalent.
- Physical euphoria
- Decreased libido - Many users note a marked decrease in their sex drive when taking gabapentin. This can happen when it is taken both recreationally or medically.
- Perception of bodily lightness - At very high doses, some users report feeling lighter.
- Dizziness - This effect is particularly prevalent at higher doses. It should be noted that the dizziness experienced on gabapentin is not always considered overly unpleasant and many users may not necessarily mind it.
- Seizure suppression - Gabapentin is commonly used as an anticonvulsant. It is often combined with other anticonvulsants when used to treat epilepsy and other seizure disorders.
- Pain relief - Gabapentin is used to control pain, particularly pain from neuropathy and restless legs syndrome. It is generally considered to be not very effective for the management of acute pain, such as opiates.
- Anxiety suppression
- Dream potentiation
- Thought deceleration
- Cognitive euphoria
- Emotion suppression
- Compulsive redosing
- Depersonalization and Derealization - At very high doses, gabapentin can induce a mild dissociative state.
- Amnesia - Gabapentin induces a substantially lower amount of amnesia compared to other GABAergic drugs such as benzodiazepines.
- Internal hallucination - At higher doses, some users report mild to strong closed eye visuals. These can include, but are not limited to psychedelic-like geometry and landscapes. It has been noted that smoking cannabis greatly potentiates these effects.
- Visual disconnection - This effect is generally quite mild and appears inconsistently at very high doses. It results in feeling as if one's sense of vision is distant or vague and being viewed through a screen or window. However, it is not capable of higher levels of visual disconnection that produce holes, spaces and voids or hallucinatory structures in the same way that traditional dissociatives can.
Anecdotal reports which describe the effects of this compound within our experience index include:
- Experience:1.2 g gabapentin, alcohol, and half of 150 mg Effexor XR - Pretty lovely for socializing and giggles
- Experience:7500mg - Analysis of gabapentin
- Experience:A combination of tramadol, clonazepam, gabapentin, and dimenhydrinate
Toxicity and harm potential
GABApentin has a low toxicity relative to dose. The most common side effects of gabapentin in adult patients include dizziness, fatigue, drowsiness, weight gain, and peripheral edema (swelling of extremities). Gabapentin may also produce sexual dysfunction in some patients whose symptoms of which may include loss of libido, inability to reach orgasm, and erectile dysfunction. Gabapentin should be used carefully in patients with renal impairment due to possible accumulation and toxicity.
It is strongly recommended that one use harm reduction practices when using this drug.
In 2009, the U.S. Food and Drug Administration issued a warning of an increased risk of depression and suicidal thoughts and behaviors in patients taking gabapentin (along with other anticonvulsant drugs), modifying the packaging insert to reflect this. A 2010 meta analysis confirmed the increased risk of suicide associated with gabapentin use.
People who accidentally or intentionally overdose may experience drowsiness, sedation, blurred vision, slurred speech, somnolence and possibly death (if a very high amount was taken and particularly if combined with alcohol). Serum gabapentin concentrations may be measured to confirm diagnosis.
Tolerance and addiction potential
Gabapentin is not considered psychologically addictive. However, it is possible to develop a physical dependence on the drug. In fact, people can experience withdrawal symptoms for up to 45 days after they stop taking gabapentin. Although gabapentin does give some people a euphoric “high” which can cause abuse, gabapentin abusers do not present with the kind of compulsive, drug-seeking behavior or strong cravings associated with other more common depressants such as opioids, alcohol or benzodiazepines.
Tolerance will develop to the anxiolytic effects with prolonged continous usage. After cessation, the tolerance returns to baseline in 7-14 days. Withdrawal symptoms or rebound symptoms may occur after ceasing usage abruptly following a few weeks or longer of steady dosing, and may necessitate a gradual dose reduction.
- Opioids - Combining opioids with gabapentin can cause death from respiratory failure.
- GABAergic depressants - Gabapentin significantly potentiates the effects of alcohol, benzodiazepines and other GABAgenics which may lead to blackouts, and dangerous behaviour.
Gabapentin is a prescription only medicine and can only be prescribed following a consultation with a doctor. It is therefore illegal to possess or sell in most parts of the world.
- Restless legs syndrome: clinical presentation diagnosis and treatment | http://www.sleep-journal.com/article/S1389-9457(15)00647-4/abstract
- EFNS guidelines on the pharmacological treatment of neuropathic pain: 2010 revision (PubMed.gov / NCBI) | https://www.ncbi.nlm.nih.gov/pubmed/20402746
- The role of anticonvulsant drugs in anxiety disorders: a critical review of the evidence (PubMed.gov / NCBI) | https://www.ncbi.nlm.nih.gov/pubmed/17502773
- Manual of Clinical Psychopharmacology | https://books.google.co.uk/books?id=D3zz1NCm3qcC&pg=PA345&hl=en
- Successful Psychopharmacology: Evidence-Based Treatment Solutions for Achieving Remission | https://books.google.co.uk/books?id=dnAlO_Veu2QC&pg=PA124&hl=en
- Neurontin Clinical Pharmacology Biopharmaceutics Review | http://www.accessdata.fda.gov/drugsatfda_docs/nda/2002/21-397.pdf_Neurontin_BioPharmr.pdf
- Gabapentin data sheet | http://reference.medscape.com/drug/neurontin-gralise-gabapentin-343011#showall
- Mechanisms of action of gabapentin (PubMed.gov / NCBI) | http://www.ncbi.nlm.nih.gov/pubmed/9686247
- R.C. Baselt, Disposition of Toxic Drugs and Chemicals in Man, 8th edition, Biomedical Publications, Foster City, CA, 2008, pp. 677–8. ISBN 978-0-9626523-7-0.