Gabapentin (Neurontin)is an anti-epileptic drug, also called an anticonvulsant. It affects chemicals and nerves in the body that are involved in the cause of seizures and some types of pain. Gabapentin is used together with other medicines to treat partial seizures in adults and children at least 3 years old. It is recommended as one of a number of first-line medications for the treatment of neuropathic pain caused by diabetic neuropathy, postherpetic neuralgia, and central neuropathic pain. About 15% of those given gabapentin for diabetic neuropathy or postherpetic neuralgia have a measurable benefit. Gabapentin is taken by mouth.
Brand Names: Gralise, Horizant, Neurontin, Gabarone
Drug Fact
Class : Gabapentinoid
Category: Prescription Only
Uses: treat partial seizures in adults and children at least 3 years old
Consumed by: adults and children at least 3 years old
Pregnancy category: C
Category C: Either studies in animals have revealed adverse effects on the fetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the fetus.
Dosage form: tablet, caplet
Side Effect :
- 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
Administration
May be taken with or without food.
Special Precautions
Patients with mixed seizures including absences, compromised respiratory function, respiratory or neurological disease, history of substance abuse (e.g. alcohol, benzodiazepines, cannabis, cocaine, opioids). Concomitant use with opioids. Avoid abrupt withdrawal. Renal impairment. Children and elderly. Pregnancy and lactation.
Adverse Reactions
Significant: Suicidal ideation and behaviour, neuropsychiatric effects in children (e.g. emotional lability, hostility, changes in behaviour and thinking, hyperkinesia), acute pancreatitis, respiratory depression, anaphylaxis, angioedema.
Blood and lymphatic system disorders: Leucopenia, thrombocytopenia.
Ear and labyrinth disorders: Vertigo, tinnitus.
Eye disorders: Nystagmus, amblyopia, diplopia.
Gastrointestinal disorders: Nausea, vomiting, diarrhoea, dry mouth, dental abnormality, dyspepsia, gingivitis, flatulence, constipation.
General disorders and admin site conditions: Fatigue, fever, peripheral oedema, abnormal gait, asthenia, malaise.
Infections and infestations: Viral infection, pneumonia, otitis media.
Injury, poisoning and procedural complications: Accidental injury, fracture.
Investigations: Weight gain, decreased WBC.
Metabolism and nutrition disorders: Anorexia, increased appetite.
Musculoskeletal and connective tissue disorders: Back pain, arthralgia, myalgia.
Nervous system disorders: Somnolence, dizziness, headache, ataxia, amnesia, tremor.
Psychiatric disorders: Confusion, depression, nervousness, anxiety.
Reproductive system and breast disorders: Impotence.
Respiratory, thoracic and mediastinal disorders: Dyspnoea, bronchitis, cough, rhinitis.
Skin and subcutaneous tissue disorders: Rash, pruritus, acne.
Vascular disorders: Hypertension, vasodilatation.
Potentially Fatal: Multiorgan hypersensitivity such as drug reaction with eosinophilia and systemic symptoms (DRESS).
Pregnancy Category (US FDA)
PO: C
Patient Counseling Information
This drug may cause dizziness and drowsiness, if affected, do not drive or operate machinery.
MonitoringParameters
Monitor renal function at baseline and periodically thereafter. Assess for signs of multiorgan hypersensitivity and suicidality (e.g. suicidal thoughts, depression, behavioural changes).
Overdosage
Symptoms: Dizziness, drowsiness, double vision, slurred speech, mild diarrhoea, lethargy, and loss of consciousness. Management: Symptomatic and supportive treatment. May consider haemodialysis in patients with severe renal impairment.
Drug Interactions
Increased risk of CNS depression (e.g. somnolence, sedation and respiratory depression) with opioids (e.g. morphine). May reduce bioavailability with antacids. May reduce renal clearance with cimetidine.
Food Interaction
May enhance CNS depressant effect of alcohol.
Lab Interference
May lead to false-positive result with certain dipstick test for total urine protein.
Action
Description: Gabapentin is structurally related to neurotransmitter GABA. It does not bind to GABAA or GABAB receptors nor influence the synthesis or uptake of GABA. It binds with high affinity to the α-2-δ-1 subunit of voltage-gated Ca channels, thereby modulating the release of excitatory neurotransmitters which participate in epileptogenesis and nociception.
Pharmacokinetics:
Absorption: Variably absorbed from the gastrointestinal tract. Bioavailability: Approx 60% (gabapentin). As gabapentin enacarbil: Approx 75% (with food); 42-65% (fasting). Time to peak plasma concentration: Approx 2-4 hours (gabapentin); As gabapentin enacarbil: 5 hours (fasting); 7.3 hours (with food).
Distribution: Widely distributed in the body. Crosses placenta and enters breast milk. Volume of distribution: 58±6 L (gabapentin); 76 L (gabapentin enacarbil). Plasma protein binding: <3%.
Metabolism: As gabapentin enacarbil: Undergoes extensive first-pass metabolism mainly in enterocytes and to a lesser extent in the liver to form gabapentin, CO2, acetaldehyde and isobutyric acid.
Excretion: As gabapentin: Mainly via urine (as unchanged drug). As gabapentin enacarbil: Mainly via urine (94%); faeces (5%). Elimination half-life: Approx 5-7 hours.
Chemical Structure
Storage
Conventional tab and cap: Store below 25°C. Oral solution: Store between 2-8°C. Extended-release tab: Store at 25°C. Protect from moisture.
ATC Classification
N03AX12 - gabapentin ; Belongs to the class of other antiepileptics.
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